JP2022117661A - Sound-absorbing skin material - Google Patents

Abstract

To provide a sound-absorbing skin material which attains sound-absorbing performance with respect to sound of a wide frequency even when having a low thickness and a low weight while being imparted with pitching resistance and icing resistance.SOLUTION: A sound-absorbing skin material is provided in which a first nonwoven fabric layer containing fibers made of a thermoplastic resin and a second nonwoven fabric layer containing short fibers made of the thermoplastic resin are interlaced to be integrated, and the first nonwoven fabric layer has interlacing holes having a hole size of 0.19 mm2 or smaller.SELECTED DRAWING: None

Description

The present invention relates to a sound absorbing surface material.

2. Description of the Related Art When a vehicle or the like is running, various noises are generated, such as noise from an engine and drive system mounted on the vehicle, road noise during running, wind noise, and the like. Sound absorbing materials are applied to wall surfaces such as engine hoods, dash panels, ceiling materials, door trims, and cab floors as noise countermeasures so that such noises do not cause discomfort to passengers. Furthermore, in recent years, in order to reduce noise to the outside of the vehicle, sound absorbing materials that use fiber materials instead of conventional resin plates are being studied for undercovers and fender liners under vehicles. However, external sound absorbing materials such as undercovers and fender liners have poor durability (chipping resistance) against foreign objects such as stones thrown up while driving (anti-chipping) and peeling of ice that adheres due to low temperatures (anti-icing). ), etc. are required. Therefore, Patent Document 1 below proposes a fender liner in which a protective layer 1 made of an LDPE resin and a protective layer 2 made of a liquid-impermeable film are arranged on a sound absorbing substrate. However, in this first protective layer, even if various durability is obtained, since the sound incident surface is a completely impermeable resin plate, sound is reflected even if the sound absorption effect in surface vibration is obtained. Therefore, a high sound absorbing effect cannot be obtained.

Further, in Patent Document 2 below, a nonwoven fabric in which a polypropylene fiber and a binder core-sheath fiber having a high-melting-point polyester as a core and a polyester having a lower melting point than polypropylene as a sheath are needle-punched and entangled on both sides of a sound-absorbing base material. There has been proposed a sound absorbing material for vehicle exteriors, in which a reinforcing layer is placed and heat-compressed to form an air-permeable membrane on the surface of the non-woven reinforcing layer, thereby improving sound absorbing properties and various durability. However, if the amount of polypropylene fiber is increased or the fiber diameter is made thinner in order to further improve sound absorption, the film will have almost no air permeability, and sound will not reach the base material layer and will be reflected. For this reason, the sound absorbing property especially for high frequencies is deteriorated.

In this way, a sound absorbing material for vehicle exteriors has been proposed by providing a functional skin material on the surface of a sound absorbing fiber base material. A skin material that achieves sound absorption performance over a wide frequency range has not yet been provided.

JP-A-2014-897 JP 2017-39453 A

In view of the above-described prior art, the problem to be solved by the present invention is to provide a sound absorbing surface material that is thin in thickness, has a low basis weight, and achieves sound absorption performance over a wide frequency range while providing chipping resistance and anti-icing properties. to provide.

The inventors of the present invention have made intensive studies and repeated experiments to solve the above problems. , a second nonwoven fabric layer containing staple fibers made of a thermoplastic resin (hereinafter also simply referred to as "second nonwoven fabric layer") is integrated by entangling, and the first nonwoven fabric layer has a pore size of 0 Unexpectedly, it was found that a sound absorbing surface material having entangled holes of 19 mm ² or less provides chipping resistance and anti-icing properties, is thin, has a low basis weight, and achieves sound absorption performance over a wide frequency range. The present invention has been completed.
That is, the present invention is as follows.

[1] A sound absorbing surface material in which a first nonwoven fabric layer containing thermoplastic resin fibers and a second nonwoven fabric layer containing thermoplastic resin staple fibers are entangled and integrated, A sound absorbing surface material, wherein one nonwoven fabric layer has intertwined pores with a pore size of 0.19 mm ² or less.
[2] The sound absorbing surface material according to the above [1], wherein the sound absorbing surface material has a thickness of 1 m or more and 5 mm or less.
[3] The sound absorbing surface material according to [1] or [2] above, wherein the first nonwoven fabric layer is integrated by thermocompression bonding.
[4] The sound absorbing according to any one of [1] to [3], wherein the first nonwoven fabric layer is a nonwoven fabric containing at least one spunbond layer (S) having an average fiber diameter of 10 μm or more and 30 μm or less. skin material.
[5] The first nonwoven fabric layer includes at least one ultrafine fiber layer (M) having an average fiber diameter of 0.3 μm or more and 7 μm or less, a basis weight of 1 g/m ² or more and 40 g/m ² or less, and an average fiber diameter of 10 μm or more. [1] to [4] above, wherein at least one spunbond layer (S) having a basis weight of 30 μm or less and a basis weight of 10 g/m ² or more and 45 g/m ² or less is integrated by partial thermocompression bonding. A sound-absorbing skin material according to any one of the above.
[6] The above [4], wherein the fibers constituting the spunbond layer (S) of the first nonwoven fabric layer contain polyethylene terephthalate, and the birefringence (Δn) of the fibers is 0.07 or more and 0.10 or less. Or the sound absorbing surface material according to [5].
[7] The first nonwoven fabric layer is partially thermocompression bonded, the partial thermocompression bonding area ratio is 5% or more and 30% or less, and the distance between the thermocompression bonded parts is the MD direction (machine direction) of the nonwoven fabric and the direction thereof. The sound absorbing surface material according to any one of the above [1] to [6], which is 0.6 mm or more and 4 mm or less in any of the perpendicular CD directions (width direction).
[8] The sound absorbing surface material according to any one of [1] to [7], wherein the second nonwoven fabric layer has a fiber diameter of 7 μm or more and 40 μm or less and a weight per unit area of 50 g/m ² or more and 300 g/m ² or less.
[9] The second nonwoven fabric layer contains two or more types of fibers, and at least one of the two or more types of fibers is a fiber containing a thermoplastic resin having a melting point of 200 ° C. or higher, [1] to The sound-absorbing skin material according to any one of [8].

The sound-absorbing skin material according to the present invention, when used as a skin material for a sound-absorbing material for vehicle exterior, provides chipping resistance and anti-icing resistance from foreign substances during driving, while having a thin thickness, a low basis weight and a wide width. Accomplish sound absorption performance at frequency.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail.
The sound absorbing surface material of the present embodiment is a sound absorbing surface material in which a first nonwoven fabric layer containing thermoplastic resin fibers and a second nonwoven fabric layer containing thermoplastic resin short fibers are entangled and integrated. A sound-absorbing surface material characterized in that the first non-woven fabric layer has intertwined pores with a pore size of 0.19 mm ² or less.

In general, a sound absorbing material exhibits sound absorbing effects in a wide range of low, medium and high frequencies by exhibiting both the porous sound absorbing effect and the planar vibration sound absorbing effect. The porous sound absorption effect is an effect of converting the vibrational energy of sound into thermal energy by friction with the skeleton, and is effective in a high frequency range. On the other hand, the surface vibration sound absorption effect is that when sound enters a dense structure, the vibration energy of the sound is received and the entire surface vibrates, and the air in the backing material layer acts as a spring. This is an effect of more efficiently vibrating the air in the layer and converting sound vibration energy into heat energy by friction with the skeleton of the base material layer, and is effective in the low frequency range.

It is preferable that the first nonwoven fabric layer and the second nonwoven fabric layer constituting the sound absorbing surface material of the present embodiment are integrated by entangling. Methods of integration by entangling include a method of integration by a needle punch method, a hydroentanglement method, an air lay method, and the like. In particular, the needle punching method and the hydroentangling method are preferable from the viewpoint of peeling strength because they easily form short fiber loops outside the first nonwoven fabric layer. An adhesive layer made of an adhesive or adhesive powder may be included between the first nonwoven fabric layer and the second nonwoven fabric layer to the extent that the weight does not increase excessively.

Conventionally, it has been believed that the presence of pores in the first nonwoven fabric layer causes channeling of air and deteriorates the sound absorbing properties of the unification by the entanglement described above. However, the present inventors found that if the size of the holes (entangled holes) generated by entangling the first nonwoven fabric layer is 0.19 mm ² or less, the decrease in sound absorption can be minimized. This effect is due to the fact that sound mainly propagates through air as a wave as a medium, and waves propagate along with the displacement (deformation) of the medium. Unlike the movement of the medium itself), it is presumed that it originates from the fact that it does not preferentially propagate in places with low pressure loss such as holes. If the first nonwoven fabric layer is sufficiently porous, there are sufficiently continuous air propagation paths in addition to the pores due to entanglement, and sound penetrates and is absorbed by the entire surface of the first nonwoven fabric layer. However, if the hole size is excessively large due to tearing or the like, it is synonymous with the absence of the first nonwoven fabric layer there, and the sound absorption deteriorates.

The first nonwoven fabric layer of the present embodiment preferably has entangled holes of 0.19 mm ² or less, more preferably has entangled holes of 0.17 mm ² or less, and has entangled holes of 0.15 mm ² or less. is more preferred. If the entangled holes of 0.19 mm ² or less are present, both the porous sound absorption effect and the plane vibration sound absorption effect can be exhibited, and the sound absorption effect can be exhibited in a wide range of low, medium, and high frequencies. . Also, from the viewpoint of peel strength, loops of short fibers formed during entangling are less likely to come off the first nonwoven fabric layer, resulting in high peel strength. The size of the pores present in the first nonwoven fabric layer is greatly related to the fiber diameter, basis weight, average pore diameter, birefringence, and needle count and perforation density of the first nonwoven fabric, as will be described later. Therefore, it can be adjusted by setting each to the optimum range.

When needle punching is performed to entangle the first nonwoven fabric layer and the second nonwoven fabric layer that constitute the sound absorbing surface material of the present embodiment, it is preferable, and particularly preferable, to use needles thinner than No. 38. is 40th to 42nd. Preferably, the needles enter from the side of the second nonwoven layer and produce loops of staple fibers on the outside of the first nonwoven layer. When the loops of the short fibers are present on the outside of the first nonwoven fabric layer, the loops of the short fibers prevent the surface of the first nonwoven fabric layer from fluffing and act as a cushion to reduce the external force applied to the first nonwoven fabric layer. This will help prevent breakage. When the sound-absorbing surface material and the sound-absorbing base material of this embodiment are integrally molded to form a sound-absorbing material, the short fiber loop surface generated on the outside of the first nonwoven fabric layer is used as the sound-absorbing material surface and the sound-absorbing base material. It does not matter which side of the material it is placed on, but by making it the sound absorbing base material side (in contact with the sound absorbing base material), the number of short fibers increases on the surface of the sound absorbing material, which improves chipping resistance and anti-icing properties. It is easy to obtain a high sound absorbing material.

In needle punching, the needle depth is preferably 5 mm or more and 15 mm or less, depending on the position of the barb of the needle. Within this range, loops of sufficient size can be formed, and the occurrence of excessively large holes can be suppressed, which is preferable for increasing entanglement and preventing peeling. Also, the piercing density is preferably 30 to 200/cm ² . If the pierced hole density is 30/cm ² or more, the peeling strength between the layers is sufficient, and if it is 200/cm ² or less, the total opening area due to the pierced holes does not become excessively large, and the first nonwoven fabric layer is torn. and less likely to break.

The first nonwoven fabric layer constituting the sound-absorbing skin material of the present embodiment preferably contains a long-fiber nonwoven fabric, and the first nonwoven fabric is preferably a spunbond nonwoven fabric. When the first nonwoven layer comprises a spunbonded nonwoven, the first nonwoven layer comprises one or more spunbonded layers (S), or at least one spunbonded layer (S) and at least one microfiber layer. It is preferably composed of a compound with (M). For example, when the spunbond layer (S) is composed of one or more layers, it is composed of S, SS, or a composite of at least one spunbond layer (S) and at least one ultrafine fiber layer (M). SM, SMS, SMM, SMMS, SMSSMS, SMSSMS, etc. are mentioned when it is sent.
When composed only of the spunbond layer (S), the strength is high and the handleability is excellent. However, from the standpoint of peel strength and sound absorption, the average pore size of the nonwoven fabric is large, making it difficult for short fibers to become entangled when loops are formed during entangling. In order to prevent these, the basis weight tends to be high. It is also possible to use a nonwoven fabric consisting of a single ultrafine fiber layer (M) without including the spunbond layer (S) as the first nonwoven fabric layer. tends to worsen.
A particularly preferred configuration for the first nonwoven fabric layer is a composite of the spunbond layer (S) and the ultrafine fiber layer (M), and in addition to the properties of the spunbond layer (S) alone, the ultrafine fiber layer A dense structure derived from (M) can be obtained, and it is easy to obtain high sound absorption due to both effects of high peel strength, porous sound absorption effect, and planar vibration sound absorption effect. In addition, by making the ultrafine fibers extremely thin, it is possible to achieve both sound absorption and handleability with a low basis weight.

It is preferable that the first nonwoven fabric layer constituting the sound absorbing surface material of the present embodiment is integrated, and from the viewpoint of sound absorption and weight reduction, integration by thermocompression bonding is desirable. Since the first nonwoven fabric layer integrated by thermocompression bonding is appropriately fixed as a surface, the surface vibration and sound absorption effect is likely to be exhibited, and since it has sufficient strength, it is easy to handle.

Thermocompression bonding includes bonding by thermocompression bonding between a known embossing roll and a smooth roll (hereinafter also referred to as a flat roll), bonding by thermocompression bonding between a smooth roll and a smooth roll, and bonding by thermocompression bonding between hot flat plates. Although it is possible, the most preferable method is to heat and press between the embossing roll and the smooth roll for bonding. In the thermocompression bonding between the embossing roll and the smooth roll, densification is suppressed in the non-thermocompression bonding part (non-embossed part), so it is difficult to block the penetration of sound. Since it is firmly integrated, it has sufficient strength and is easy to handle. It can be applied to members that require thermoforming, and can be used in a wide range of applications.

When bonding by thermocompression bonding between the embossing roll and the smoothing roll, partial thermocompression bonding is preferably performed at a compression area ratio of 5% or more and 30% or less with respect to the total area of the nonwoven fabric, more preferably 7% or more. 25% or less. When the thermocompression bonding area ratio is 5% or more, there is little fluffing, and when it is 30% or less, the nonwoven fabric is less likely to become paper-like, and mechanical properties such as elongation at break and tear strength are less likely to decrease.
The temperature for thermocompression bonding should be appropriately selected according to conditions such as the basis weight of the web to be supplied, the speed, etc., and it cannot be determined indiscriminately. The temperature is preferably 90° C. or lower, more preferably 40° C. or higher and 70° C. or lower. In addition, when the embossing roll and the smooth roll are joined by heating and pressure bonding, and when the type of resin in contact with the embossing roll surface and the type of resin in contact with the smooth roll surface are the same, the temperature difference between the embossing roll and the smooth roll is It is preferably less than 10°C, more preferably less than 5°C, and even more preferably less than 3°C. However, this does not apply when the melting point of the resin in contact with the embossed roll surface and the resin in contact with the flat roll surface are different, or when the pulling force during spinning and the oriented crystallinity of the yarn are different. If the temperature difference between the embossing roll and the smooth roll is within the above range, moldability is improved.

The pressure for thermocompression bonding should also be appropriately selected according to conditions such as the basis weight of the web to be supplied and the speed. It is preferably 30 N/mm or more and 70 N/mm or less. If the pressure for thermocompression bonding is within the above range, good thermocompression bonding between fibers can be performed, and the resulting nonwoven fabric can have appropriate mechanical strength, rigidity, and dimensional stability. .
The shape of the thermocompression bonding portion is not particularly limited, but is preferably a texture pattern, an eye pattern (rectangular pattern), a pinpoint pattern, a diamond pattern, a square pattern, a tortoiseshell pattern, an elliptical pattern, a checkered pattern, a polka dot pattern, or a circular pattern. A pattern can be exemplified.

In the case of bonding by heating and pressing between smooth rolls, or when bonding by heating and pressing between hot flat plates, pressure is applied to the entire surface of the nonwoven fabric, so the entire surface becomes excessively dense and does not hinder the penetration of sound. Similarly, it is preferable to perform thermocompression bonding at low pressure and low temperature to the extent that delamination does not occur.

The distance between the partially thermocompressed parts transferred to the nonwoven fabric by partial thermocompression bonding is in the range of 0.6 to 4 mm both in the MD direction (machine direction) of the nonwoven fabric and in the CD direction (width direction) perpendicular to that direction. is preferred, more preferably 0.8 to 3.5 mm, still more preferably 1 to 3 mm. If the distance between the partial thermocompression bonding portions is within the above range, it is possible to suppress an excessive increase in the rigidity of the nonwoven fabric, and it is possible to sufficiently suppress the phenomenon that the non-crimped yarns with a high degree of freedom come off from the crimping portions and become fuzzy. . In addition, during entangling such as needle punching and water entanglement, the degree of freedom of the spunbond fibers around the hole generated in the non-partial thermocompression bonding area tends to be high, and the yarn is cut very little by the needle and water flow, and the spunbond The fibers remain so as to surround the holes, making it difficult for excessive holes to open, and good sound absorption can be achieved.

The basis weight of the first non-woven fabric layer constituting the sound absorbing upholstery material of this embodiment is preferably 20 to 100 g/m ² , more preferably 20 to 70 g/m ² . When the basis weight of the first nonwoven fabric layer is 20 g/m ² or more, it tends to have a sufficiently dense structure, and the fixation of the second nonwoven fabric layer and the first nonwoven fabric layer at the time of entangling becomes strong. In addition, it is easy to achieve the required strength for protecting the second nonwoven fabric layer from wear and the like, and it is easy to blind the second nonwoven fabric layer from the viewpoint of design. When the basis weight of the first nonwoven fabric layer is 100 g/m ² or less, excessive densification can be suppressed, sound reflection in areas other than the holes generated during entangling is small, and sound can penetrate to the second nonwoven fabric layer. It is easy to obtain the sound absorbing effect of the entire sound absorbing surface material. In addition, it is easy to obtain the flexibility, extensibility, and conformability of the sound-absorbing surface material, and it is easy to use even in members that require these characteristics, such as hood insulators, which require thermoforming.

When the first nonwoven fabric layer constituting the sound absorbing surface material of the present embodiment is a composite of the spunbond layer (S) and the ultrafine fiber layer (M), at least one layer having an average fiber diameter of 0.3 μm or more and 7 μm or less It is preferably a nonwoven fabric in which the ultrafine fiber layer (M) and at least one spunbond layer (S) having an average fiber diameter of 10 μm or more and 30 μm or less are integrated. By setting the average fiber diameter within the above range, both the sound absorbing effect and the handleability can be achieved. Furthermore, the spunbond layer (S) can prevent the pores of the ultrafine fiber layer (M) from expanding during entangling such as needle punching and hydroentangling, and the spunbond layer (S) can be prevented from expanding during stretching. Since it acts as a column and does not apply extreme stress to the ultrafine fiber layer (M), the ultrafine fiber layer (M) can be stretched uniformly without breaking.

As a method for producing the first nonwoven fabric layer that constitutes the sound absorbing surface material of this embodiment, a single layer or laminated web is produced by a series of spinning processes, and during transport, a low pressure nip between a smooth precompaction roll and a conveyor net. and then heat-pressing between the embossing roll and the smooth roll to bond. For example, in SMS construction, a spunbond layer (S1) is sprayed onto the conveyor, then a microfiber layer (M) is sprayed onto the spunbond layer (S1), and finally a spunbond layer (S2) is sprayed onto the microfiber layer ( M) Spray on. During transportation, the spunbond layers (S1 and 2) After spraying, a smooth pre-compaction roll may be used with a low pressure nip between the pre-compaction roll and the conveyor net. A web that has been lightly consolidated by a precompaction roll is heat-pressed between an embossing roll and a smooth roll. In this way, by going through the step of spraying the ultrafine fiber layer (M) onto the spunbond layer (S) and the integration step in precompaction, the non-partially thermocompression-bonded portion is also the ultrafine fiber layer (M) and the spunbond layer ( The spunbond layer (S) can promote the integration of the microfiber layer (S), the spunbond layer (S) can prevent the pores of the microfiber layer (M) from expanding during entangling, and the spunbond layer (S) can be stretched during stretching. ) serves as a column, and extreme stress is not applied to the ultrafine fiber layer (M), so that the ultrafine fiber layer (M) can be stretched uniformly without breaking.

The heating temperature of the pre-compaction roll is preferably, for example, a temperature lower than the melting point of the fibers present on the roll contact surface by 60° C. or more and 100° C. or less, and the pressure is preferably 1 N/mm or more and 10 N/mm or less, more preferably. It is 3 N/mm or more and 7 N/mm or less.

A known spunbond method can be used for spinning the spunbond layer (S) of the first nonwoven fabric layer that constitutes the sound absorbing surface material of the present embodiment. Conditions for uniform dispersion are preferred. Using such conditions facilitates the production of unbonded webs and is economical. Also, the web of spunbond layers may be a single layer or multiple layers.

A thermoplastic resin that can be fiberized by a melt spinning method is used as a material for forming the first nonwoven fabric layer that forms the sound absorbing upholstery material of the present embodiment. Examples of thermoplastic resins include polyolefin resins (polyethylene, polypropylene, copolymer polypropylene, etc.), aromatic polyester resins, aliphatic polyester resins (poly D-lactic acid, poly L-lactic acid, D-lactic acid and L- a copolymer of lactic acid, a copolymer of D-lactic acid and hydroxycarboxylic acid, a copolymer of L-lactic acid and hydroxycarboxylic acid, a copolymer of D-lactic acid, L-lactic acid and hydroxycarboxylic acid; These blends, etc.), polyamide-based resins (polyamide 6, polyamide 66, copolyamide, etc.), polyphenylene sulfide, and the like. As the thermoplastic resin, an aromatic polyester-based resin, which is particularly excellent in heat resistance and water resistance, is preferably used. The aromatic polyester-based resin is a thermoplastic polyester, and typical examples include polyethylene terephthalate (PET), polybutylene terephthalate, and polytrimethylene terephthalate. The aromatic polyester-based resin may also be a polyester obtained by polymerizing or copolymerizing isophthalic acid, phthalic acid, or the like as an acid component that forms an ester. From the viewpoint of environmental consideration, the thermoplastic resin is preferably plant-derived rather than petroleum-derived.
However, elastomer resins, such as block copolymer polyesters having hard and soft segments, are substantially difficult to spin due to the imbalance between elastic restoring force and elongation stress of elastomers, and have very low spin rates. It is not preferable because only high speed and large fiber diameter can be obtained.

Spunbond in contact with the second nonwoven layer of the acoustical upholstery when the first nonwoven layer is a laminated nonwoven fabric comprising a spunbond layer (S) and the spunbond layer (S) is in contact with the second nonwoven layer Layer (S) may contain fibers having a melting point that is at least 30° C. lower than the melting point of the fibers of the other layers. That is, in order to maintain good adhesion between the first nonwoven layer and the second nonwoven layer, the layer in contact with the second nonwoven layer may be composed of low-melting-point fibers. Examples of low-melting fibers include aromatic polyester copolymers obtained by copolymerizing polyethylene terephthalate with one or more of phthalic acid, isophthalic acid, sebacic acid, adipic acid, diethylene glycol, and 1,4-butanediol. Coalesced fibers, polyester fibers such as aliphatic ester fibers, and the like are included. These fibers may be used alone, or two or more of them may be combined together, or a low-melting point fiber and a high-melting point fiber may be combined together. Further, a composite fiber having a sheath-core structure having a low-melting-point component in the sheath may be used. Examples of sheath-core composite fibers include polyethylene terephthalate, polybutylene terephthalate, and copolymerized polyester whose core is a high melting point component, and copolymerized polyester and aliphatic ester whose sheath is a low melting point component.

The average fiber diameter of the fibers constituting the spunbond layer (S) is preferably 10.0 µm or more and 30.0 µm or less, more preferably 12.0 µm or more and 30.0 µm or less, still more preferably 12.0 µm or more and 20.0 µm. Below, more preferably 13.0 μm or more and 20.0 μm or less, most preferably 13.0 μm or more and 18.0 μm or less. When the average fiber diameter of the fibers constituting the spunbond layer (S) is 10.0 μm or more, spinning stability is high, and when it is 30 μm or less, strength and heat resistance are excellent.
The basis weight of the spunbond layer (S) is preferably 10 g/m ² or more and 45 g/m ² or less, more preferably 10 g/m ² or more and 30 g/m ² or less. If the basis weight is 10 g/m ² or more, it has sufficient strength and can suppress excessive piercing and tearing due to needles and water flow in entangling processing such as needle punching and hydroentangling. If it is ² or less, it is light.

The birefringence (Δn) of the fibers constituting the spunbond layer (S) after thermocompression bonding is preferably 0.07 to 0.100, more preferably 0.07 to 0.100, for polyethylene terephthalate (PET), for example. 07 to 0.095, more preferably 0.07 to 0.09. If the birefringence (Δn) is 0.07 or more, a sufficient amount of heat can be applied during partial thermocompression bonding, and the nonwoven fabric will be resistant to heat shrinkage. On the other hand, if the birefringence (Δn) is 0.100 or less, a fiber with a high elongation and a low elastic modulus is obtained, and unexpectedly, needles and water flow penetrated by entangling processing such as needle punching and hydroentangling. When the fibers are bent, they are less likely to be cut, making it easier to obtain the effect of reducing the size of the pores. The birefringence can be controlled by the roll temperature during partial thermocompression bonding and the traction force of a traction device during spinning.

In the spunbond method, it is common to use a high-speed airflow traction device with an air jet, and the traction force is changed by the amount of air introduced into the traction device. This traction force is the same length as the total length of the traction device (fishing line) with a diameter of 0.235 mm (In this specification, Toray nylon line "Ginrin (No. 2 / natural / 50m winding single)" was used. ) Two were put into the traction device, the stress was measured by the spring measurement connected to the extremity, and the traction force (mN/m) was measured by dividing it by the length of the expelled extremity. A preferable traction force for adjusting the birefringence (Δn) to the above range is 50 mN/m or more and 100 mN/m or less, more preferably 50 mN/m or more and 80 mN/m or less, and most preferably 60 mN/m or more and 70 mN/m. m or less.

When the first nonwoven fabric layer that constitutes the sound absorbing surface material of the present embodiment includes the ultrafine fiber layer (M), the ultrafine fiber layer (M) is preferably produced by a meltblowing method. In the meltblowing method, since the molten resin is pulled by high-temperature, high-speed air immediately after it is discharged from the spinning nozzle, the production cost is relatively low and it is easy to obtain a fine fiber diameter. However, due to the characteristics of the manufacturing method, it is difficult to solidify the melted and extruded resin, and the superfine fiber layer (M) becomes excessively hard due to the fusion of the fibers, etc., and the effect of returning and reducing the pores that occur during entangling. is sometimes difficult to obtain. Therefore, in order to prevent this fusion between fibers, it is preferable to appropriately adjust the resin viscosity, the spray distance onto the conveyer or the spunbond layer (S), and the like.

When the material of the ultrafine fiber layer (M) is PET or its copolymer, the solution viscosity (ηsp/c) of the ultrafine fibers is preferably from 0.35 to 0.6, more preferably from 0.37 to 0. 0.55 or less. When the solution viscosity (ηsp/c) of the ultrafine fibers of PET or its copolymer is 0.3 or more, the solidification can be accelerated and the fusion between the fibers can be suppressed. If the solution viscosity (ηsp/c) of the ultrafine fibers of PET or its copolymer is 0.6 or less, fine fibers can be easily obtained, so excessive drawing energy is not required, and production costs can be reduced.

The distance between the melt blow nozzle and the collecting surface is preferably 100 mm or more and 180 mm or less, more preferably 110 mm or more and 150 mm or less, still more preferably 120 mm or more and 140 mm or less. If the distance between the melt blow nozzle and the collecting surface is 100 mm or more, fusion between the ultrafine fibers can be easily suppressed even if the temperature and flow rate of the heated air are increased. On the other hand, if the distance between the melt blow nozzle and the collecting surface is 180 mm or less, entanglement between fibers in the air is unlikely to occur, and spots are unlikely to occur. etc. will be handled well.

The average fiber diameter of the ultrafine fiber layer (M) is preferably 0.3 μm or more and 7 μm or less, more preferably 0.4 μm or more and 5 μm or less, still more preferably 0.6 μm or more and 2 μm or less. If the average fiber diameter is 0.3 μm or more, the spinning by the melt blow method does not require severe conditions, and the fibers can be stably obtained. On the other hand, if the average fiber diameter is 7 μm or less, a sufficient sound absorbing effect can be obtained. ) in the form of fine fibers to fill the gaps, a dense structure can be obtained, and the sound absorbing effect can be further enhanced.

The basis weight of the ultrafine fiber layer (M) is preferably 1 g/m ² or more and 40 g/m ² or more, more preferably 2 g/m ² or more and 25 g/m ² or less, and still more preferably from the viewpoint of obtaining sufficient sound absorption with a low basis weight. is 3 g/m ² or more and 20 g/m ² or less.

As the material of the ultrafine fiber layer (M), thermoplastic synthetic resins that can be used for the spunbond layer (S) can be similarly used. However, elastomer resins, such as block copolymer polyesters having hard and soft segments, are difficult to spin due to the imbalance between the elastic restoring force and the elongation stress of the elastomer, resulting in very low spinning speeds and thick fibers. It is not preferable because only the diameter can be obtained.

The shape of the fiber cross section of the first non-woven fabric layer constituting the sound absorbing surface material of the present embodiment is not particularly limited, but from the viewpoint of strength, a circular cross section is preferable, and from the viewpoint of increasing the surface area of the fiber and forming fine voids. A modified cross-section yarn such as a flat yarn is preferable.

The average pore size of the first nonwoven fabric layer constituting the sound absorbing surface material of the present embodiment before entangling and integrating is preferably 1 μm or more and 30 μm or less, more preferably 2 μm or more and 20 μm, from the viewpoint of peel strength and sound absorption. Below, it is more preferably 5 μm or more and 15 μm or less. If the average pore diameter is 1 μm or more, the membrane is not excessively dense and impedes the penetration of sound. On the other hand, if the average pore diameter is 30 μm or less, the sound absorption is improved due to the moderately dense structure, and the force that tends to return the pores generated during entangling tends to work, and excellent peel strength is likely to be obtained.

The first nonwoven fabric layer constituting the sound absorbing upholstery material of the present embodiment may be coated with a resin. In particular, when it is composed only of the spunbond layer (S), it is highly preferable to apply a resin coating in order to obtain a sound absorbing effect due to a dense structure with a low basis weight. The resin coating amount is preferably 3 g/m ² or more and 25 g/m ² or less, more preferably 3 g/m ² or more and 20 g/m ² or less. If the amount of resin coating is within the above range, the effect of sufficiently closing the gaps between fibers can be expected, and it is easy to suppress the adhesion of resin to the mold during thermoforming, and the sticking of the molded body to the mold can be prevented. It is possible to suppress and obtain good moldability.

As the resin used for the resin coating, it is preferable to use an aqueous solution, an aqueous emulsion, or an aqueous dispersion from the viewpoint of ease of handling. Thermosetting resins and thermoplastic resins can be used as resins, and thermosetting resins include urethane resins, melamine resins, ester bond type thermosetting acrylic resins, phenolic resins, and thermosetting polyester resins. etc. are used. Polyester-based resins, acrylic-based resins, and the like are used as thermoplastic resins.

One of the preferred thermosetting resins is an ester bond type thermosetting acrylic resin. Ester bond type thermosetting acrylic resins are cured by an esterification reaction between an acid of a polymer obtained by radical polymerization of an ethylenically unsaturated dicarboxylic acid and a hydroxyl group contained in alkanolamine having a hydroxyl group. In this case, only water is produced as a by-product during the curing reaction, and harmful substances such as formaldehyde are not produced as a by-product.

Another preferred thermosetting resin is a phenol-alkylresorcin cocondensate of a phenolic resin. The phenol-alkylresorcin cocondensate has good stability in aqueous solution and has the advantage of being able to be stored for a long period of time at room temperature as compared with a condensate consisting of only phenol. In addition, alkylresorcinol has a high reactivity with formaldehydes and captures and reacts with free aldehyde, so there is an advantage that the amount of free aldehyde in the resin is reduced.

A preferable thermoplastic resin is a polyester-based resin. Polyester-based resins have a relatively high glass transition point, and after coating, they are less sticky even when dried at a low temperature, have a good feel, and have little resin transfer.

A filler may be mixed in the resin used for the resin coating for the purpose of making the first nonwoven fabric layer dense. Fillers include hollow granules such as shirasu balloons, perlite, glass balloons, hollow ceramics, plastic foams and foamed granules, inorganic materials such as calcium carbonate, magnesium carbonate, magnesium hydroxide, aluminum hydroxide, alumina, silica, and colloidal silica. Fillers and the like are exemplified. Among these, hollow granules such as Shirasu balloons are desirable because they are hollow inside and therefore easily contribute to the improvement of sound absorption performance.

The average particle diameter of the filler is preferably 1 to 100 μm, more preferably 10 to 90 μm, still more preferably 15 to 70 μm. If the average particle size of the filler is 1 μm or more, the voids are appropriately formed, and the penetration of sound becomes sufficient, so that the sound absorbing effect can be easily enhanced. On the other hand, if the average particle diameter of the filler is 100 μm or less, the formation of excessively large gaps can be easily suppressed, and the surface area can be easily provided while making the skin dense. The mixing ratio of the filler and the resin used for the resin coating can be 55:45 to 70:30 in solid content ratio. Within this range, the filler adheres sufficiently to the skin material, and the possibility of filling the gaps between the fillers with the resin can be reduced.

As a resin coating method, a coating method on one side such as a roll coater, a knife coater or a flow coater, or a method of coating the entire thickness direction by impregnation such as dip nip can be used. In the case of being composed only of the spunbond layer (S), from the viewpoint of suppressing adhesion of resin to the mold during thermoforming, or suppressing sticking of the molded body to the mold, A coating method in which a resin is present, especially roll coating, is desirable. On the other hand, for example, in the case of a composite of a spunbond layer (S) and a microfiber layer (M) such as SMS, the dip nip is also affected by surface tension due to the resin liquid adhering to the surface of the microfiber layer (M). is generated, and the resin hardly oozes out to the surface of the spunbond layer (S), so it is possible to suppress the adhesion of the resin to the mold during thermoforming, or to suppress the sticking of the molded body to the mold. is desirable because it allows Furthermore, since the resin exists in the entire thickness direction of the skin material, it is easy to make the skin dense with a very small amount of resin.

The drying temperature of the resin coating is preferably in the range of 100-130°C. Within this range, the resin liquid can be sufficiently dried, and the decrease in flexibility and moldability due to the promotion of crystallization of the fibers constituting the first nonwoven fabric layer by heat can be suppressed. When a flexible resin is used, hardening before thermoforming can be suppressed, and excellent moldability can be exhibited during thermoforming.

Black pigment, flame retardant such as phosphorus, and water repellent are mixed in the resin liquid of resin coating at the same time to impart black coloration, flame retardancy, and water repellency necessary for surface materials such as hood insulators. can be done.

The bulk density of the first nonwoven fabric layer that constitutes the sound absorbing surface material of the present embodiment is preferably 0.1 g/cm ³ or more and 0.7 g/cm ³ or less, more preferably 0.15 g/cm ³ or more. It is 0.6 g/cm ³ or less, more preferably 0.2 g/cm ³ or more and 0.55 g/cm ³ or less. If the bulk density is 0.1 g/cm ³ or more, the denseness of the nonwoven fabric is improved and the sound absorption is improved. On the other hand, if the bulk density is 0.7 g/cm ³ or less, the density of the nonwoven fabric is not too high, sound penetration is sufficient, the sound absorption coefficient at medium frequencies around 4000 Hz is particularly difficult to decrease, and workability is improved.

The first nonwoven fabric layer that constitutes the sound absorbing surface material of the present embodiment has a dry heat shrinkage rate of preferably 5% or less, more preferably 4% or less in 10 minutes in an atmosphere of 180 ° C., more preferably 3%. .5% or less. When it is 5% or less, wrinkles are less likely to occur due to shrinkage during molding.

The thickness of the second non-woven fabric layer constituting the sound-absorbing upholstery material of the present embodiment is preferably 1 mm to 5 mm. When the thickness is 5 mm or less, the shape stability is excellent and the space is saved.

The bulk density of the second nonwoven fabric layer used in the sound absorbing material of the present embodiment is preferably 0.01 g/cm ³ or more and 0.1 g/cm ³ or less, more preferably 0.02 g/cm ³ or more and 0.08 g/cm 3 or more. cm ³ or less, more preferably 0.03 g/cm ³ or more and 0.05 g/cm ³ or less. If the bulk density is 0.01 g/cm ³ or more, the sound absorbing property is unlikely to deteriorate, and there is no need to increase the thickness more than necessary. On the other hand, if the bulk density is 0.1 g/cm ³ or less, sound transmitted through the first nonwoven fabric layer easily enters the second nonwoven fabric layer, and abrasion resistance and workability are also improved. The bulk density of the second nonwoven fabric layer may be adjusted in advance by compression using a known hot press or the like before integration by entangling with the first nonwoven fabric layer.

The basis weight of the second non-woven fabric layer constituting the sound absorbing upholstery material of this embodiment is 50 to 500 g/m ² , preferably 100 to 300 g/m ² . If the basis weight is 50 g/m ² or more, the chipping resistance and the anti-icing property can be fully exhibited, which is preferable in terms of the bulkiness and soft feel of the nonwoven fabric. On the other hand, if the weight per unit area is 500 g/m ² or less, the thickness is appropriate, the space can be saved, and weight reduction can be expected.
The fiber length of the short fibers of the second non-woven fabric layer constituting the sound absorbing surface material of this embodiment is preferably 38 to 150 mm, particularly preferably 50 to 100 mm. When the fiber length is 38 mm or more, excellent sound absorption coefficient is exhibited, and when it is 150 mm or less, spinnability from the card is good.
The average fiber diameter of the short fibers of the second non-woven fabric layer constituting the sound absorbing surface material of the present embodiment is preferably 15.0 μm or more and 40.0 μm or less, more preferably 20.0 μm or more and 30.0 μm or less. If it is 15.0 μm or more, the spinnability from the card is improved, and clogging of the surface after molding can be suppressed. When the thickness is 40.0 μm or less, an excessive increase in thickness can be suppressed, and a sound absorbing effect can be expected.

The second non-woven fabric layer constituting the sound-absorbing skin material of this embodiment contains short fibers made of thermoplastic fibers. The short fibers contain 50 to 90% by weight of short fibers having a melting point of less than 200° C. and 10 to 50% by weight of short fibers having a melting point of 200° C. or higher. preferably contains 60 to 80% by weight of fibers having a melting point of less than 200°C, and more preferably contains 20 to 40% by weight of fibers having a melting point of 200°C or higher. Thermoplastic resins having a melting point of less than 200 ° C. include polyolefin resins (polyethylene, polypropylene, copolymerized polypropylene, etc.), aliphatic polyester resins (poly D-lactic acid, poly L-lactic acid, D-lactic acid and L-lactic acid a copolymer of D-lactic acid and hydroxycarboxylic acid, a copolymer of L-lactic acid and hydroxycarboxylic acid, a copolymer of D-lactic acid, L-lactic acid and hydroxycarboxylic acid, these and the like), and polyesters obtained by polymerizing or copolymerizing isophthalic acid, phthalic acid, etc. as acid components forming esters. From the viewpoint of versatility, polyolefin resins and copolymerized polyester resins are preferred. Examples of resins having a melting point of 200° C. or higher include aromatic polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate, polyamide resins such as polyamide 6, polyamide 66 and copolyamide, and polyphenylene sulfide. From the viewpoint of versatility, polyethylene terephthalate (PET) and polybutylene terephthalate are preferred. From the viewpoint of environmental consideration, the fiber resin is preferably plant-derived rather than petroleum-derived.
Both the fiber with a melting point of less than 200°C and the fiber with a melting point of 200°C or more may be a single component, or may be a composite fiber of multiple components such as a mixture of two or more types or a sheath-core structure.

The sound absorbing skin material of the present embodiment preferably has a thickness of 1 mm to 5 mm, more preferably 2 mm to 4 mm. When the thickness is 1 mm to 5 mm, the sound absorbing surface material is thin and lightweight, and a high sound absorbing effect can be obtained in a relatively wide range of sound frequencies.

The peel strength between the first nonwoven fabric layer and the second nonwoven fabric layer of the sound absorbing surface material of the present embodiment is preferably 1.8 N/5 cm or more, more preferably 1.9 N/5 cm or more, further preferably 2 N/5 cm or more. If the peel strength is 1.8 N/5 cm or more, the problem of peeling during cutting, transportation, etc. of the sound absorbing material is less likely to occur.

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to these. The direction of flow (machine direction) in the production of nonwoven fabrics is called the MD direction, and the width direction perpendicular to that direction is called the CD direction.
Each physical property in the following examples etc. was obtained by measuring by the following method. In principle, the various physical properties of the present invention are measured by the following methods, but if there is a reason that the following methods cannot be measured, it is possible to measure them by a reasonable alternative method.

(1) Hole size (area) of interlaced holes (mm ² )
A sample is cut out from an arbitrary point to a width of 5 cm in the CD direction and a length of 5 cm in the MD direction, and from the first nonwoven fabric layer side, a 200-fold enlarged photograph is taken using a microscope VHX-700F manufactured by Keyence Corporation. The area of the focused hole in the observation field was calculated using polygonal area measurement, the area was measured at 20 points, and the average value was obtained.

(2) Peel strength (N/5 cm)
A sample is cut out to a width of 5 cm in the CD direction and a length of 20 cm in the MD direction, and the non-woven fabric skin material layer is peeled off by 5 cm or more in the length direction. The first non-woven fabric layer is held on the second non-woven fabric layer, and the second non-woven fabric layer is held on the lower chuck. The above measurements were performed 5 times, and an average value was obtained.

(3) basis weight (g/m ² )
The fabric weights of the first nonwoven fabric layer and the second nonwoven fabric layer were measured according to JIS L 1913. In addition, in the laminate (sound absorbing surface material and the first nonwoven fabric layer which is a laminated nonwoven fabric), the basis weight of each layer was calculated from the manufacturing conditions in this example. If the manufacturing conditions are unknown, the basis weight of each layer can be measured in accordance with JIS L 1913 after peeling off layers that can be delaminated to form a single layer. If delamination cannot be performed, an X-ray CT image of the nonwoven fabric can be taken, and from the X-ray CT image, calculation can be made from the area of the observation range, the volume occupied by the ultrafine fiber layer, the resin density, and the thickness.

(4) Average fiber diameter (μm)
Using a microscope VHX-700F manufactured by KEYENCE CORPORATION, a magnified photograph of 500 times was taken, and the average value of 10 fibers in focus in the observation field was obtained.

(5) bulk density (g/cm ³ )
It was calculated from (basis weight)/(thickness) to obtain the weight per unit volume.

(6) Thickness (mm)
Complies with JIS L 1913 B method. Three or more thicknesses were measured under a load of 0.02 kPa, and the average value was obtained.

(7) Birefringence (Δn)
Fibers are collected from the spunbond layer of the non-partially thermocompressed portion of the first nonwoven fabric layer, and birefringence is determined from retardation and fiber diameter by a normal interference fringe method using a BH2 type polarizing microscope compensator manufactured by OLYMPUS. was measured. The above measurements were performed on 20 fibers, and the average value was defined as the birefringence. In addition, when the first nonwoven fabric layer was thermocompression-bonded by thermocompression over the entire surface between smooth rolls, fibers were collected from the spunbond layer at an arbitrary location and measured.

(8) Pore size distribution (average pore size)
A PMI Perm Porometer (model: CFP-1200AEX) was used. Silwick manufactured by PMI was used as the immersion liquid for the measurement, and the sample was immersed in the immersion liquid and degassed sufficiently before the measurement. Using a filter as a sample, the filter is immersed in a liquid whose surface tension is known in advance, and pressure is applied to the filter in a state in which all the pores of the filter are covered with a liquid film. and the pore size of the pore calculated from the surface tension of the liquid. The following formula is used for calculation:
d=C・r/P
{Wherein, d (unit: μm) is the pore size of the filter, r (unit: N/m) is the surface tension of the liquid, P (unit: Pa) is the pressure at which the liquid film of that pore size breaks, and C is a constant. } is used.
From the above formula, the flow rate (wet flow rate) is measured when the pressure P applied to the filter immersed in the liquid is continuously changed from low pressure to high pressure. At the initial pressure, the flow rate is zero because even the largest pore liquid film is not broken. As the pressure is increased, the liquid film in the largest pores breaks and a flow occurs (bubble point). As the pressure is further increased, the flow rate increases according to each pressure. The flow rate at the pressure at which the smallest pore liquid film breaks corresponds to the dry state flow rate (dry flow rate).
In the measurement method using this measuring device, the value obtained by dividing the wet flow rate at a certain pressure by the dry flow rate at the same pressure is called the cumulative filter flow rate (unit: %). The pore size of the liquid film that breaks at the pressure at which the cumulative filter flow rate is 50% is called the average pore size. This average pore diameter was used as the average pore diameter of the present invention.

(9) Production of Molded Sound Absorbing Material As the sound absorbing base material, polyethylene terephthalate fibers (melting point: 250° C.) of 480 g/m ² having a single fiber fineness of 4.3 dtex (fiber diameter: 20 μm) and a cut length of 51 mm, and a single fiber fineness of 4.3 dtex (fiber diameter: 20 μm). Using 320 g/m ² polypropylene fibers (melting point 160° C.) of 1 dtex (fiber diameter: 24 μm) and 51 mm in fiber length, a staple fiber web having a basis weight of 800 g/m ² was produced by a carding machine. A needle-punched nonwoven fabric is obtained by entangling with needles of a count needle at a needle depth of 10 mm and a piercing density of 100/m ² . The needle incident side of the sound absorbing surface material was placed on the sound absorbing base material so that the needle incident side was on the surface, and after pressing with a mold having a clearance of 5.5 mm at 200 ° C. for 30 seconds, the clearance was immediately increased to 5 mm. It was fixed in a cooled mold at normal temperature, and a molded body (molded sound absorbing material) was produced.

(10) Ice resistance (Ice peel strength)
The molded sound absorbing material obtained in (9) above was measured under the following conditions under the test method disclosed in JP-A-2012-245925.
(i) The size of the test piece was 40 mm or more in length and 40 mm or more in width.
(ii) A square pipe (JISG3466) having a length of 40 mm, a width of 40 mm, a height of 30 mm and a thickness of 1.6 mm is prepared. A hole is provided in the central portion of the side surface at a position of 5 mm from the end surface of one end of the square pipe.
(iii) In an atmosphere of minus 15° C., the square pipe is placed on the non-woven fabric layer 15 of the test piece with the end face opposite to the end face provided with the hole out of both ends being in contact with each other. Then, 0.5 to 1.0 g of ice water at 0 to 3° C. is sprayed into the square pipe with a sprayer every 5 minutes to form icicles with a height of 15 mm on the bottom of the nonwoven fabric layer.
(iv) A load meter is attached to the hole of the square pipe to measure the peeling load when the icicle inside the square pipe is peeled off.

(11) Chipping resistance The molded sound absorbing material obtained in (9) above is a cube under the test method disclosed in Japanese Patent Application Laid-Open No. 2017-39453, and the average length of length, width and depth 3 kg of pebbles with a length of 3 mm to 7 mm were dropped from a height of 2 m, and changes in the surface were observed.

(12) Sound absorption coefficient measurement In accordance with JIS A 1405, the above (9 ) was provided with 10 mm of air behind, and the sound absorption coefficient (%) at frequencies of 1000 Hz, 2500 Hz and 5000 Hz was obtained as a representative value.

[Example 1]
Polyethylene terephthalate (1% using orthochlorophenol, solution viscosity ηsp/c of 25°C method (melt viscosity shown below is also measured under the same conditions) is 0.77, melting point 263°C) resin is It is supplied to a spinning device and melted at 300 ° C., discharged from a spinneret having a spinning hole with a circular cross section, and drawn with a high-speed air current drawing device using an air jet with a drawing force of 66 mN / m while cooling the yarn and making a long fiber. A web (S1) (basis weight 11.5 g/m ² , average fiber diameter 15 μm) was formed on a net and nipped between a precompaction roll with a smooth surface temperature of 160° C. and a conveyor net at a low pressure of 4 N/mm. Polyethylene terephthalate (solution viscosity ηsp/c: 0.50, melting point: 260°C) was spun onto the obtained filament web (S1) from a melt blow nozzle at a spinning temperature of 300°C, heated air of 320°C, and 1000 Nm ³ /hr. A microfiber web (M) (basis weight: 7.0 g/m ² , average fiber diameter: 1.8 μm) was formed. At this time, the distance from the melt blow nozzle to the filament web (S1) was set to 110 mm, and the suction wind speed on the collection surface immediately below the melt blow nozzle was set to 7 m/sec. Furthermore, after forming a polyethylene terephthalate filament web (S2) on the obtained ultrafine fiber web in the same manner as the filament web (S1), it is placed between a smooth surface temperature of 160°C pre-compaction rolls and a conveyor net. The layers were lightly integrated by nipping at a low pressure of 4 N/mm. Next, the obtained laminated web was subjected to a calender wire using a texture pattern embossing roll and a flat roll having a compression area ratio of 15%, the surface temperature of the embossing roll being 220 ° C. and the surface temperature of the flat roll being 210 ° C. By thermocompression bonding at a pressure of 30 N/mm, a nonwoven fabric layer having a basis weight of 30 g/m ² , a bulk density of 0.27 g/cm ³ , a birefringence of the spunbond layers (S1 and S2) of 0.071, and an average pore size of 10 μm. got
Next, polyethylene terephthalate staple fibers (melting point: 250°C) with a fineness of 4.3 dtex (fiber diameter: 20 µm) and a fiber length of 51 mm (50 g/m ² ) and polypropylene staple fibers with a fineness of 4.1 dtex (fiber diameter: 24 µm) and a fiber length of 51 mm. (Melting point 160°C) 150 g/m ² was used to form a staple fiber web having a basis weight of 200 g/m ² on the nonwoven fabric layer using a carding machine. The thickness was 10 mm, and the hole density was 100 holes/ ^cm2 . Its properties are shown in Table 1 below.

[Example 2]
The basis weight of the long fiber webs (S1, S2) of the nonwoven fabric layer is 15.4 g/m ² , and the basis weight of the ultrafine fiber web (M) is 9.2 g/m ² . A sound-absorbing surface material was obtained in the same manner as in Example 1, except that an 11% IEL pattern embossing roll was used. Its properties are shown in Table 1 below.

[Example 3]
Sound absorption was carried out in the same manner as in Example 1, except that the basis weight of the long fiber webs (S1, S2) of the nonwoven fabric layer was 19.2 g/m ² and the basis weight of the ultrafine fiber web (M) was 11.6 g/m ² . A skin material was produced. Its properties are shown in Table 1 below.

[Example 4]
Polyethylene terephthalate (solution viscosity ηsp/c: 0.77, melting point: 263° C.) resin is supplied to a conventional melt spinning apparatus and melted at 300° C., discharged from a spinneret having a circular cross-section spinning hole, and air jetted. The yarn is cooled while drawing with a pulling force of 100 mN / m using a high-speed air current pulling device by , to form a long fiber web (S1) (weight per unit area: 11.5 g / m ² , average fiber diameter: 13 μm) on the net, smooth It was nipped at a low pressure of 4 N/mm between a pre-compaction roll having a surface temperature of 160° C. and a conveyor net. Polyethylene terephthalate (solution viscosity ηsp/c: 0.50, melting point: 260°C) was spun onto the obtained filament web (S1) from a melt blow nozzle at a spinning temperature of 300°C, heated air of 320°C, and 1000 Nm ³ /hr. A microfiber web (M) (basis weight: 7.0 g/m ² , average fiber diameter: 1.8 μm) was formed. At this time, the distance from the melt blow nozzle to the filament web (S1) was set to 110 mm, and the suction wind speed on the collection surface immediately below the melt blow nozzle was set to 7 m/sec. Furthermore, a polyethylene terephthalate filament web (S2) was formed on the obtained ultrafine fiber web in the same manner as the filament web (S1), and was rolled between a smooth surface temperature of 160° C. pre-compaction rolls and a conveyor net at 4N/ The layers were lightly integrated by nipping at a low pressure of mm. Next, the obtained laminated web was subjected to a calendering process using a texture pattern embossing roll and a smoothing roll having a compression area ratio of 15%, the surface temperature of the embossing roll being 235 ° C. and the surface temperature of the smoothing roll being 235 ° C. A nonwoven fabric layer having a basis weight of 30 g/m ² , a bulk density of 0.27 g/cm ³ , a spunbond layer having a birefringence of 0.110, and an average pore size of 10 μm was obtained by thermocompression bonding at a pressure of 30 N/mm. Next, polyethylene terephthalate staple fibers (melting point: 250°C) with a fineness of 4.3 dtex (fiber diameter: 20 µm) and a fiber length of 51 mm (50 g/m ² ) and polypropylene staple fibers with a fineness of 4.1 dtex (fiber diameter: 24 µm) and a fiber length of 51 mm. (Melting point 160°C) 150 g/m ² was used to form a staple fiber web having a basis weight of 200 g/m ² on the nonwoven fabric layer using a carding machine. The thickness was 10 mm, and the hole density was 100 holes/ ^cm2 . Its properties are shown in Table 1 below.

[Example 5]
A sound-absorbing surface material was produced in the same manner as in Example 1, except that a texture pattern embossing roll having a compression area ratio of 20% was used as the embossing roll when the nonwoven fabric layer was thermally compressed. Its properties are shown in Table 1 below.

[Example 6]
Polyethylene terephthalate (solution viscosity ηsp/c: 0.77, melting point: 263° C.) resin is supplied to a conventional melt spinning apparatus and melted at 300° C., discharged from a spinneret having a circular cross-section spinning hole, and air jetted. The yarn was cooled while being drawn with a drawing force of 70 mN/m using a high-speed air current drawing device by , to form a long fiber web (S1) (basis weight: 70.0 g/m ² , average fiber diameter: 15 µm) on a net. Next, the obtained filament web was subjected to a texture pattern embossing roll having a compression area ratio of 15% and a smooth roll, and the surface temperature of the embossing roll was set to 235 ° C. and the surface temperature of the smooth roll was set to 230 ° C., A nonwoven fabric having a basis weight of 70 g/m ² , a bulk density of 0.29 g/cm ³ , a birefringence of the spunbond layer (S1) of 0.080, and an average pore diameter of 21 μm by thermocompression bonding at a calendar linear pressure of 30 N/mm. got a layer.
Next, polyethylene terephthalate staple fibers (melting point: 250°C) of 50 g/m ² with a fineness of 4.3 dtex (fiber diameter: 20 µm) and a fiber length of 51 mm, and polypropylene short fibers with a fineness of 4.1 dtex (fiber diameter: 24 µm) and a cut length of 51 mm. Using 150 g/m ² of fiber (melting point 160° C.), a staple fiber web with a basis weight of 200 g/m ² is formed on the nonwoven fabric layer by a carding machine, and from the staple fiber web side, using a 40-count needle, needles Depth: 10 mm, piercing density: 100 holes/cm ² , needle punch integration processing was performed to obtain a sound absorbing surface material. Its properties are shown in Table 1 below.

[Comparative Example 1]
Polyethylene terephthalate staple fibers (melting point: 250°C) with a fineness of 4.3 dtex (fiber diameter: 20 µm) and a fiber length of 51 mm (50 g/m ² ) and polypropylene staple fibers with a fineness of 4.1 dtex (fiber diameter: 24 µm) and a fiber length of 51 mm (melting point: 160° C.) 150 g/m ² was used to prepare a staple fiber web having a basis weight of 200 g/m ² with a carding machine. This short fiber web was integrated by needle punching using a No. 40 needle with a needle depth of 10 mm and a piercing density of 100 holes/cm ² to obtain a sound absorbing surface material. Its properties are shown in Table 2 below.

[Comparative Example 2]
Only the long-fiber nonwoven fabric layer before needle-punch integration with the short-fiber web of Example 1 was used as the sound-absorbing surface material. Its properties are shown in Table 2 below.

[Comparative Example 3]
Polyethylene terephthalate (solution viscosity η sp / c is 0.50, melting point 260 ° C.) is blown out from a melt blow nozzle under the conditions of a spinning temperature of 300 ° C., heated air of ³²⁰ ° C. and 1000 Nm / hr on the net, and a microfiber web ( M) (basis weight 30.0 g/m ² , average fiber diameter 1.8 μm) was formed. At this time, the distance from the melt blow nozzle to the net is set to 100 mm, the suction wind speed on the collection surface directly under the melt blow nozzle is set to 11 m / sec, the basis weight is 30 g / m ² , the bulk density is 0.38 g / cm ³ , the average pore diameter A nonwoven layer of 6 μm was obtained. Polyethylene terephthalate staple fibers (melting point: 250°C) with a fineness of 4.3 dtex (fiber diameter: 20 µm) and a fiber length of 51 mm (50 g/m ² ) and polypropylene staple fibers with a fineness of 4.1 dtex (fiber diameter: 24 µm) and a fiber length of 51 mm (melting point: 160° C.) 150 g/m ² , a staple fiber web having a basis weight of 200 g/m ² is formed on the nonwoven fabric layer by a carding device, and from the staple fiber web side, using a No. 40 needle, needle depth: A sound-absorbing surface material was obtained by needle-punching integral processing with a 10 mm hole density of 100 holes/cm ² . Its properties are shown in Table 2 below.

[Comparative Example 4]
Except that the basis weight of the long fiber web (S1) of the nonwoven fabric layer was 30.0 g/m ² , the surface temperature of the embossing roll was 230 ° C., and the surface temperature of the flat roll was 225 ° C. during thermocompression bonding. A sound absorbing surface material was produced in the same manner as in Example 6. Its properties are shown in Table 2 below.

[Comparative Example 5]
A sound-absorbing surface material was produced in the same manner as in Example 4, except that, during thermocompression bonding, the material was thermocompressed between two smooth rolls having a compression area ratio of 100% and a temperature of 238° C. with a calender linear pressure of 30 N/mm. Its properties are shown in Table 2 below.

The sound absorbing surface material according to the present invention is thin, has a low basis weight, and can provide sound absorption performance over a wide frequency range, while being able to provide chipping resistance and anti-icing properties. As a sound-absorbing surface material for undercovers, fender liners, and indoor trunks, it can be used as a sound-absorbing surface material for housing. It can be suitably used as a sound absorbing surface material in insulators and construction machines.

Claims (9)

A sound absorbing surface material in which a first nonwoven fabric layer containing thermoplastic resin fibers and a second nonwoven fabric layer containing thermoplastic resin short fibers are entangled and integrated, wherein the first nonwoven fabric A sound-absorbing skin material, characterized in that the layer has interlaced pores with a pore size of 0.19 mm ² or less. 2. The sound absorbing upholstery material according to claim 1, wherein the first nonwoven fabric layer has a thickness of 1 m or more and 5 mm or less. 3. The sound absorbing upholstery material according to claim 1, wherein said first nonwoven fabric layer is integrated by thermocompression bonding. The sound absorbing surface material according to any one of claims 1 to 3, wherein the first nonwoven fabric layer is a nonwoven fabric containing at least one spunbond layer (S) having an average fiber diameter of 10 µm or more and 30 µm or less. The first nonwoven fabric layer includes at least one ultrafine fiber layer (M) having an average fiber diameter of 0.3 μm or more and 7 μm or less and a basis weight of 1 g/m ² or more and 40 g/m ² or less, and an average fiber diameter of 10 μm or more and 30 μm or less, 5. The laminated nonwoven fabric according to any one of claims 1 to 4, wherein at least one spunbond layer (S) having a basis weight of 10 g/m ² or more and 45 g/m ² or less is integrated by partial thermocompression bonding. sound-absorbing skin material. 6. The fiber according to claim 4 or 5, wherein the fibers constituting the spunbond layer (S) of the first nonwoven fabric layer contain polyethylene terephthalate, and the birefringence (Δn) of the fiber is 0.07 or more and 0.10 or less. sound-absorbing skin material. The first nonwoven fabric layer is partially thermocompression-bonded, the partial thermocompression bonding area ratio is 5% or more and 30% or less, and the distance between the thermocompression bonding parts is the MD direction (machine direction) of the nonwoven fabric and the CD perpendicular to that direction. The sound absorbing surface material according to any one of claims 1 to 6, which is 0.6 mm or more and 4 mm or less in any direction (width direction). The sound absorbing surface material according to any one of claims 1 to 7, wherein the second nonwoven fabric layer has a fiber diameter of 7 µm or more and 40 µm or less and a weight per unit area of 50 g/m ² or more and 300 g/m ² or less. Any one of claims 1 to 8, wherein the second nonwoven fabric layer contains two or more types of fibers, and at least one of the two or more types of fibers is a fiber containing a thermoplastic resin having a melting point of 200°C or higher. 2. The sound-absorbing skin material according to item 1.