JP2021172038A - Fiber laminate structure - Google Patents

Abstract

To provide a fiber laminate structure having excellent sound absorption properties particularly in both of low frequency region and high frequency region even with a thin thickness.SOLUTION: A fiber laminate structure includes a nonwoven fabric having a basis weight of 800 g/m2 or less and a sheet with an open hole having a basis weight of 70 g/m2 or more alternately laminated. At least two layers of the sheets with an open hole are included in the structure.SELECTED DRAWING: None

Description

The present invention relates to a fiber laminated structure, and further relates to a fiber laminated structure having excellent sound absorption.

In recent years, vehicles such as automobiles have undergone remarkable technological innovations related to electrification, automatic driving (assist), and IT. Along with this, there is an increasing need for creating a comfortable environment so that the time for boarding or driving a vehicle becomes more valuable time and space. At the same time, the engine noise disappears due to the electrification and EV of automobiles, but for passengers, noise caused by motors and road noise due to weight reduction cannot be ignored as noise sources while the vehicle is running. It has become to. Therefore, there is an ever-increasing demand for quietness inside the vehicle. Such needs are the same for railway vehicles and the like.

Various people have been proposed as soundproof fiber structures that have been conventionally used in vehicles, houses, highways, and the like.

For example, there are felts in which wood boards and recycled fibers are impregnated with a thermosetting binder such as phenol resin, and fiber structures in which inorganic fibers such as glass fibers are impregnated with a thermoplastic resin and hot-pressed or cold-pressed (for example). , Patent Document 1). Further, a fiber structure composed of a high melting point thermoplastic fiber and a low melting point thermoplastic fiber in which a part of the low melting point thermoplastic fiber is heat-sealed (see, for example, Patent Document 2) and an inelastic crimp short. A sound absorbing fiber structure composed of fibers and heat-adhesive composite short fibers, formed with scattered fixing points by heat fusion of the heat-adhesive composite short fibers, and the fibers are arranged in the thickness direction (for example,). (See Patent Document 3), a fiber structure in which a woven or knitted fabric and a non-woven fabric are bonded together with a hot melt adhesive (see, for example, Patent Document 4), and a fiber aggregate in which two or more kinds of fibers having different thicknesses are blended (see, for example, Patent Document 4). For example, various structures such as a fiber structure made of a single laminate of a film and a non-woven fabric (see, for example, Patent Document 6) have been proposed.

However, the main purpose is often to reduce the weight and cost, and the performance obtained by them is not sufficient. In particular, in the case of a sound absorbing material for vehicles such as automobiles and railways, there is a restriction that it must be placed inside the vehicle structure, so that a structure having excellent sound absorbing performance even if it is thinner has been required.

Japanese Unexamined Patent Publication No. 59-227442 Japanese Unexamined Patent Publication No. 07-3599 Japanese Unexamined Patent Publication No. 2001-207366 Japanese Unexamined Patent Publication No. 2003-334881 Japanese Unexamined Patent Publication No. 07-219556 JP-A-2019-209569

An object of the present invention is to provide a fiber laminated structure having excellent sound absorbing characteristics even in a thin fiber laminated structure, and particularly having good sound absorbing characteristics in a low frequency region and a high frequency region.

[1] Non-woven fabric having a basis weight of 800 g / m ² or less and a sheet having a basis weight of 70 g / m ² or more are alternately laminated, and the through hole occupies the area of one side of the sheet having the through hole. A fiber laminated structure having an area ratio of 0.1 to 20% and containing at least two or more sheets having the through holes.
[2] The fiber laminated structure according to [1], wherein the reverberation room method sound absorption coefficient of 1000 Hz is 0.3 or more and the reverberation room method sound absorption coefficient of 3500 Hz is 0.3 or more.
[3] The fiber laminated structure according to [1] or [2], wherein the fibers constituting the non-woven fabric contain fibers having a single yarn fineness of 1.0 dtex or less.
[4] A sheet having a through hole having a ^{basis weight of 70 g / m 2} or more is arranged at at least one end of the fiber laminated structure in the laminating direction [1] to [3]. The fiber laminated structure according to any one of.
[5] The fiber laminated structure according to any one of [1] to [4], wherein the total thickness of the fiber laminated structure is 5 cm or less.

According to the present invention, it is possible to provide a fiber laminated structure having good sound absorption characteristics in each of the low frequency region and the high frequency region, despite the thin fiber laminated structure.

In the fiber laminated structure of the present invention, a non-woven fabric having a basis ^{weight of 800 g / m 2 or less and a sheet having a through hole having a basis weight of 70 g / m 2} or more are alternately laminated, and one surface of the sheet having the through hole is formed. It is a fiber laminated structure in which the area ratio of the through holes to the area is 0.1 to 20%, and at least two or more sheets having the through holes are included. Hereinafter, since a plurality of types of non-woven fabrics and a plurality of types of sheets may be disclosed in Examples and the like, the non-woven fabric may be referred to as “nonwoven fabric 1” and the sheet may be referred to as “sheet 2” for convenience.

<Fibers constituting the non-woven fabric 1>
The non-woven fabric 1 is made of natural fibers or chemically synthesized fibers. Among these, chemically synthesized fibers are preferable from the viewpoints of practical properties such as durability and mechanical properties as well as processability, and nylon fibers, acrylic fibers, rayon fibers, polyester fibers, aramid fibers, and polyvinyl chloride fibers are preferable. Examples thereof include fibers and polyolefin fibers. Among these, polyester fibers are particularly preferable in consideration of availability and price in addition to the above-mentioned characteristics. Examples of the polyester used here include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, poly-1,4-dimethylcyclohexylene terephthalate, polyethylene naphthalate, polytrimethylene naphthalate and polybutylene naphthalate. , Polypivalolactone, polylactic acid (PLA), or a polyether ester composed of a copolymer of these, a component such as a polyether diol or a polycarbonate diol, and a polyester, and the like can also be exemplified. Further, various stabilizers, ultraviolet absorbers, thickening branching agents, matting agents, colorants, and various other improving agents may be blended in the polymer to be used, if necessary. Among them, polyethylene terephthalate and / or polybutylene terephthalate are particularly preferable examples from the viewpoint of silk-reeling processability. Two or more of these fibers can be mixed and used. The single-thread fineness of the fibers used is not particularly limited, and conventionally known single-thread fineness fibers can be used. As a preferable upper limit of the single yarn fineness, the smaller the single yarn fineness, the larger the surface area of the fiber per unit weight and the surface area of the non-woven fabric can be increased, and as a result, the sound absorbing effect due to the air viscosity attenuation becomes higher, which is preferable. .. For example, a single yarn fineness of 20 dtex or less can be exemplified as a preferable example. It is more preferably 10 dtex or less, still more preferably 5 dtex or less, and even more preferably 1.0 dtex or less. On the other hand, as a preferable example of the lower limit of the single yarn fineness, a range in which the filling efficiency (bulk density) of the fiber is not lowered and the handleability and durability as a non-woven fabric are not lowered is preferable. More specifically, it is preferable to use fibers of 0.0001 dtex or more. More preferably, 0.001 dtex or more, and further preferably 0.01 dtex or more.

In particular, when fibers with low fineness (fineness) are used, the handling and durability of the non-woven fabric can be improved by using fibers with relatively high fineness at the same time. Therefore, the fibers used for the non-woven fabric. It is exemplified as a preferable example that the fiber of the above fineness is used as a part of. The fiber morphology includes ordinary round cross-section fibers, hollow fibers, polygons of triangle or more, ellipse, leaf shape, multi-leaf shape, slit shape and other irregular cross-section fibers, side-by-side structure made of two or more types of polymers, and core. It is also possible to take the form of a conjugated fiber (composite fiber) such as a sheath structure or a sea-island structure.

Further, in order to entangle the above-mentioned fibers to form a sheet-shaped non-woven fabric 1, it is preferable that the fibers used are short fibers having crimps. In this case, any conventionally known method can be adopted as the method for imparting crimp. The most common method is mechanical crimping in which fibers are mechanically bent by a push-in crimper method and appropriately heat-treated, but as another method, for example, polymers having different heat shrinkage rates are attached to a side-by-side type. Examples thereof include a method of imparting spiral crimping using a combined composite fiber and a method of imparting spiral crimping by heterogeneous cooling during melt spinning. Among these, mechanical crimping is exemplified as the most suitable crimping method from the viewpoint of mass productivity and manufacturing cost. The number of crimps is not particularly limited, but is generally 1 to 50 pieces / 2.54 cm, more preferably 3 to 30 pieces / 2.54 cm, and further preferably 5 to 20 pieces / 2.54 cm. Is. As the fiber length of the short fiber, 10 to 100 mm is exemplified as a preferable example. More preferably, it is 20 to 80 mm, and further preferably 30 to 70 mm. If the short fiber length is too short, the non-woven fabric 1 may not have sufficient elasticity. On the other hand, if the short fiber length is too long, the homogeneity and process stability may decrease due to fiber entanglement and the like.

It is preferable that the non-woven fabric 1 is partially or wholly made of fibers having heat-adhesiveness or heat-sealing property at a relatively low temperature (hereinafter, referred to as heat-adhesive fibers). By containing these heat-adhesive fibers, it is possible to appropriately heat and shape the fibers into an arbitrary shape, and the entangled points between the fibers can be firmly adhered to each other, so that the shape can be maintained and the durability can be maintained. A non-woven fabric 1 having excellent properties can be obtained. Further, it is preferable that 1/2 or more of the surface area of the heat-adhesive fiber is occupied by a polymer exhibiting adhesiveness. For example, a fiber having a core-sheath structure in which a fiber having a high melting point such as polyethylene terephthalate is used as a core component and a polymer showing thermal adhesiveness at a relatively low temperature is used for the sheath portion, or the above-mentioned two kinds of polymers are used. Fibers with a side-by-side structure are particularly preferred. Alternatively, by adopting such a core-sheath structure, the elasticity of the adhesive fiber is maintained even during shape shaping by heat, the shaping workability is improved, and the texture of the non-woven fabric after shaping is good. Is easy to obtain. In the case of a combination of a polymer having a high melting point and a polymer exhibiting thermal adhesiveness, the amount ratio thereof is in the range of 30/70 to 70/30 for the polymer having a high melting point / the polymer exhibiting thermal adhesiveness in terms of weight ratio. A preferred example is given. As the form of the fiber, the diameter of the short fiber is preferably in the range of about 2 to 50 μm, more preferably in the range of 3 to 20 μm. The short fiber length is preferably in the range of 10 to 100 mm, more preferably in the range of 20 to 80 mm. Examples of other adhesive polymers include polymers having a relatively low melting point such as polyethylene.

The melting point of the polymer exhibiting thermal adhesiveness used here is preferably a polymer exhibiting fuseability at 70 to 180 ° C. It is more preferably 80 to 170 ° C, still more preferably 90 to 160 ° C. Alternatively, the melting point of the polymer exhibiting thermal adhesiveness is preferably 40 ° C. or higher lower than that of the fiber having a high melting point used in combination. Examples of polymers exhibiting such adhesiveness include various copolymerized polyesters and polyether ester elastomers. More specific copolymerized polyesters include aliphatic dicarboxylic acids such as adipic acid and sebacic acid, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and naphthalenedicarboxylic acid, and / or hexahydroterephthalic acid and hexahydroisophthalic acid. Examples thereof include those in which alicyclic dicarboxylic acids such as are used as a dicarboxylic acid component, and aliphatic or alicyclic diols such as diethylene glycol, propylene glycol, tetramethylene glycol, polyethylene glycol, and paraxylene glycol are used as a diol component. These can be used in combination in a desired ratio, and further, hydroxy acids such as parahydroxybenzoic acid can be added. For example, a copolymerized polyester obtained by copolymerizing so-called polyethylene terephthalate, which is a combination of terephthalic acid and ethylene glycol, with isophthalic acid as a dicarboxylic acid copolymerization component and diethylene glycol, 1,6-hexanediol or the like as a diol copolymerization component. Etc. can be given as a preferable example. Various stabilizers, ultraviolet absorbers, thickening branching agents, matting agents, colorants, and various other improving agents can be appropriately added to these polymers exhibiting thermal adhesiveness.

<Manufacturing method of non-woven fabric 1>
The method for producing the nonwoven fabric 1 used in the fiber laminated structure of the present invention is not particularly limited, and any conventionally known production method may be used. In particular, a method in which one or more types of ostrich fibers are mixed and released as a uniform web by a roller card, and then the web is heated while being folded into an accordion shape to form a fixing point by heat fusion (for example, commercially available). As a manufacturing apparatus for the above, it can be mentioned as a preferable example that an ostrich facility manufactured by Ostrich Co., Ltd. is adopted. In addition, a method of folding and superimposing the web using a cross layer and then heat-sealing treatment, or a method of aligning the mixed cotton / opened constituent fibers by an air flow to make the surface cylindrical and mesh-like. It is also preferable to form a fiber web by focusing on the peripheral surface of the suction drum by applying an air flow. As a web forming apparatus by the air array method suitable for such a web forming process, "V12 / R" manufactured by AUTEFA or "RANDO-WEBBER" manufactured by RANDO (registered by the company). Trademark) and the like. Further, it is preferable to perform such molding and then heat-bonding treatment to produce the nonwoven fabric 1.

The non-woven fabric 1 used in the present invention needs to be ^{800 g / m 2 or less.} More preferably, it is 700 g / m ² or less, and even more preferably 500 g / m ² or less. The lower limit is not particularly limited as long as there is no problem in handleability, but when the basis weight ^{exceeds 800 g / m 2} , the finally obtained fiber laminated structure of the present invention is thick. In some cases, the hardness becomes harder and the shape becomes harder or lower. In addition, a low basis weight is preferable because it increases the weight. The lower limit is not particularly limited as long as there is no problem in handleability, but is substantially 30 g / m ² or more. It is more preferably 50 g / m ² or more, and even more preferably 70 g / m ² or more.

<Sheet 2>
Next, the sheet 2 used for the fiber laminated structure of the present invention will be described. The sheet 2 is a sheet having a through hole having a basis weight of 70 g / m ^{2 or more.}

Examples of the material used for the sheet 2 include organic polymers and metals. Organic polymers include polyolefins such as polyethylene and polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyesters such as polybutylene naphthalate, nylon 6, nylon 4,6, nylon 6,6, nylon. 11. Polyamides (nylons) such as MX nylon, polyvinyl chloride, polyvinyls such as polystyrene, acrylics such as polymethyl methacrylate and methyl polyacrylate, polycarbonates, and polyphenylene sulfide, poly. Thermoplastic elastomers such as ether sulfone, aramids (total aromatic polyamide), polyimides, triacetates, polyester esters, synthetic natural rubber, butadiene rubber, chloroprene rubber, silicone rubber, acrylic rubber, urethane rubber, fluororubber (FKM) and the like. As metals, aluminum, gold, silver, copper, stainless steel, titanium, tantalum, molybdenum, niobium, zirconium, tungsten, beryllium copper, phosphor bronze, brass, white, tin, lead, zinc, solder, iridium, iron, Nickel, permalloy, nichrome, 42 alloy, copper foil, monel foil, inconel foil, hastelloy foil can be appropriately selected and used according to the weather resistance, heat resistance, stiffness, etc. according to the application. Among these, polyolefins, polyesters, polyamides, polycarbonates, aramids, and thermoplastic elastomers can be mentioned as more preferable examples from the viewpoints of practical properties, manufacturing cost / availability, and processability. As the metal, aluminum, copper, and stainless steel are also exemplified as more preferable examples from the viewpoints of practical characteristics, manufacturing cost, and processability. Further, these sheets may be a dense sheet having no voids / pores inside, or a porous structure or a foam structure having voids / pores, but the workability is improved. From the viewpoint of specific gravity from the viewpoint of sound insulation, a structure having a desired porosity can be set. Among these, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polycarbonates, polyether ester elastomers, and metals such as aluminum and copper are particularly preferable examples. The polyesters referred to here have the same meaning as the polyesters described above in the description of the non-woven fabric 1, and include copolymerized polyesters. In addition to various bisphenols and isosorbides, the polycarbonates referred to here include linear aliphatic diols such as tetramethylenediol, hexamethylenediol and nonanediol, and alicyclic diols such as dimethylcyclohexylenediol. -Includes copolymers obtained by polymerization. Further, various stabilizers, ultraviolet absorbers, thickening branching agents, matting agents, colorants, lubricants, and various other improving agents may be blended in the polymer to be used, if necessary. The term "aluminum" as used herein also includes alloys and alloys in which an inorganic component other than aluminum is added at 30% or less. By formulating the copolymerization of the polymer and the alloying of the metal in this way, various physical properties such as mechanical properties, processability and shapeability can be adjusted according to the purpose.

It is essential that the sheet 2 used in the present invention has a through hole in the thickness direction. By providing the through hole, in addition to the resonance in the frequency region peculiar to the sheet, it is possible to appropriately pass the sound in all frequency bands, and the ventilation resistance value and the maze degree in the entire fiber laminated structure of the present invention are improved. It also plays a role in improving sound absorption performance. As a result, the sound absorption performance of the object of the present invention can be achieved. The through hole provided in the sheet 2 used in the present invention preferably has an area ratio of 0.1 to 20% to the area of one side of the sheet. If the area ratio occupied by the through holes is less than 0.1%, the sound transmitted through the sheet may be insufficient, and as a result, the sound absorption performance in the high frequency region may deteriorate. On the other hand, if it exceeds 20%, the sound may be transmitted too much and the sound absorption effect of the resonance frequency may be insufficient. More preferably, it is in the range of 0.5 to 15%, and even more preferably, it is in the range of 1 to 10%. The shape of the through hole is not particularly limited, and it is a polygonal shape such as a circle, a triangle, a square, a rectangular parallelepiped, a slit shape, a star shape, a heart shape, a leaf shape, a multi-leaf shape, a musical note shape, or a treble symbol shape. , A syllabary, a katakana character, an alphabet character, a Greek character, and the like, and any shape of through hole that also has a design can be used. Of these, round, square, and slit shapes are more preferable from the viewpoint of processing. The size of the through holes and the number of through holes can be arbitrarily set within a range that satisfies the above-mentioned area ratio of the through holes. However, if the size of the through holes is small, it is necessary to form a large number of through holes at high density, and conversely, if the size of the through holes is large, the number is small, so that the sound absorption effect varies depending on the location. There is a possibility that it will be done. For example, in the case of a round through hole, the diameter is generally about 0.01 to 50 mm. It is more preferably in the range of 0.05 to 40 mm, still more preferably in the range of 0.1 to 30 mm. In the case of a through hole other than the round shape, the area corresponding to the size of the round through hole described above can be rephrased as a preferable range. Further, the through holes may be uniformly distributed or may be arbitrarily distributed with a bias. In particular, when there is a bias in the location of sound generation or sound transmission, the distribution of through holes can be intentionally arranged in consideration of these points. The through holes are basically arranged in the depth direction with respect to the seat surface, but may not be completely perpendicular to the seat surface, or may be about plus / minus 45 ° with respect to the seat surface. There is no problem even if there is a slope. Further, the through hole itself may be tapered to some extent. In this case, the area ratio of the through holes can be calculated based on the cross-sectional area of the portion having the smallest area when cut on a plane parallel to the sheet surface.

<Manufacturing method of sheet 2>
The method for producing these sheets 2 is not particularly limited, and any conventionally known method can be used. For example, the manufacturing process is mainly divided into a sheet film forming process and a hole forming process. For example, in the case of polyester, a biaxial stretching method is preferable as a method for producing the sheet. More specifically, for example, polyester resin pellets are supplied to an extruder, melted at around 290 ° C., and extruded into a slit shape on a rotary cooling drum in a molten state to obtain an unstretched film. Then, a biaxial stretching method in which a sheet can be obtained by stretching in a biaxial direction in a mechanical flow direction (MD direction) and then in a width direction (TD direction) is exemplified. The polyester film is further composed of a raw material containing 2 to 50% by weight of heat-resistant fine particles such as barium sulfate, titanium dioxide, calcium carbonate or silicon dioxide in the polyester resin, and is a white film having voids inside or the polyester resin. A white film containing 1 to 20% by weight of an incompatible resin is particularly preferable. In this case, the microporous structure is formed starting from the particles or the incompatible resin. When the film has a microporous structure, the sound absorption may be improved due to the microporous structure at the same time as the weight reduction. The technique for microporousing the polyester film used in the present invention is not limited to the above, and a foamed polyester sheet obtained by melt-extruding a polyester resin containing a foaming agent can also be preferably used.

<Through hole of sheet 2>
Subsequently, a step of drilling a through hole provided in the sheet 2 will be described. Any conventionally known process may be used for drilling the through hole. For example, punching / punching with a punch, drilling, cutting / machining with an end mill of NC machine tools (Numerically Controlled Machine Tools), laser processing, pattern cutting with a water jet or sand, chemicals such as alkali. Etching process by the above is exemplified. Among these, punching / punching with a punching die, machining with a drilling or NC machine tool, and laser machining can be mentioned as more preferable examples from the viewpoint of productivity. Depending on the material used in particular, it may be deformed or changed in color due to heat during processing, so the most suitable material may be selected and processed according to the material, processed while cooling, or holes. It is advisable to process while considering the position of opening and the order of opening so as not to store heat in the material.

The sheet 2 preferably has a basis weight of 5 g / m ² or more. If the basis weight of the sheet 2 is smaller and thinner than this, it is not preferable from the viewpoint of handleability in a manufacturing process such as drilling, or from the viewpoint of the sound absorption performance of the present invention. More preferably, it is 10 g / m ² or more, and even more preferably 30 g / m ² or more. Since the fiber laminated structure of the present invention has a repeating structure of a non-woven fabric and a sheet structure, it is possible to sufficiently exhibit its sound absorbing performance and maintain flexibility and suppleness even if the single unit is not extremely thick. Therefore, it has a feature of being excellent in shapeability to the shape of the article to be coated with the fiber laminated structure of the present invention. On the other hand, the upper limit is determined from the viewpoint of maintaining suppleness and drilling workability, but practically, 1000 g / m ² or less, 500 g / m ² or less, and 300 g / m ² or less are particularly preferable. However, in the case of applications where flexibility is not required, this is not the case, and there is no problem even if the sheet is thicker than the above range. Specifically, the basis weight of the sheet 2 is 70 g / m ² or more, more preferably 100 g / m ² or more, and 130 g / m ² or more. The upper limit can be exemplified by 1500 g / m ² or less, more preferably 1000 g / m ² and 800 g / m ^2. Further, even when a stretchable elastomer such as a polyether ester, silicone, or rubber is used as a material, the flexibility can be maintained even if it is relatively thick, so that it can be used in this range as well. From the viewpoint of shape processability, thermoplastic elastomers such as polyether ester elastomers and polycarbonate ester elastomers can be particularly preferably used. Further, the same applies to a sheet having flexibility depending on the form of the foamed sheet.

Since the sheet 2 of the present invention needs to have adhesiveness to a non-woven fabric or an article to be coated due to the form and properties of the invention, the surface thereof is subjected to corona treatment, plasma treatment, primer treatment and various adhesive coating treatments. , Some processing may be done. Therefore, the basis weight of the sheet 2 referred to here represents the weight (g) per square meter including the adhesive of the treatment layer such as the adhesive.

<Fiber laminated structure of non-woven fabric 1 and sheet 2>
The fiber laminated structure of the present invention is a structure in which the non-woven fabric 1 and the sheet 2 as described above are alternately laminated, and includes at least two or more sheets 2. A laminated structure containing at least two layers of sheet 2, that is, a three-layer structure of sheet 2 / non-woven fabric 1 / sheet 2 in which the non-woven fabric 1 is superposed on the sheet 2 and the sheet 2 is further superposed on the sheet 2. , It is a simple structure having the smallest number of laminates in the present invention, and is an essential lamination mode in the fiber laminate structure of the present invention. More preferably, a laminated structure having four or more layers of sheet 2 / non-woven fabric 1 / sheet 2 / non-woven fabric 1 is exemplified, and 5 or more layers are more preferable, and 6 or more layers are particularly preferable. As the number of laminated structures increases, the frequency at which sound is absorbed based on the natural resonance of the sheet 2 shifts to the lower frequency side. Therefore, originally, in order to set the desired sound absorption characteristics, the number of layers can be appropriately designed and selected. The upper limit is not particularly limited, but is within the range in which the total thickness of the fiber laminated structure of the present invention does not become excessively thick, or the balance between cost in the manufacturing process, productivity and sound absorption performance, shapeability, and handleability. Can also be set including. It is practically about 30 layers. It is more preferably 20 layers or less, still more preferably 10 layers or less. Each non-woven fabric 1 and / or sheet 2 is used for each layer, but may have the same specifications or different specifications for each layer as long as it is within the above-mentioned specifications. Further, from the viewpoint of sound absorption performance, shapeability, and handleability described above, in the fiber laminated structure of the present invention, it is preferable that the sheet 2 is arranged at at least one end of the fiber laminated structure in the laminating direction. More preferably, the sheets 2 are both ends in the stacking direction. In other words, it is preferable that at least one of the components of the uppermost layer and the lowermost layer in the stacking direction of the fiber laminated structure is the sheet 2, and it is more preferable that both the components of the uppermost layer and the lowermost layer are the sheet 2. ..

<Manufacturing method of fiber laminated structure>
As the laminated structure, the method of fixing the non-woven fabric 1 and the sheet 2 is any of conventionally known methods such as a physical fixing method such as sewing with fibers or wires, and a method of fixing with an adhesive or an adhesive. Can be used. Further, as long as the fibers of the non-woven fabric 1 and the sheet 2 can be stably contacted with each other by, for example, external pressure without using an adhesive or the like, it is included in the definition of fixation in the present invention. Here, it is important that the sheet 2 is fixed only to the adjacent non-woven fabric 1. That is, the sewing thread or the like is fastened to another sheet 2 provided via the non-woven fabric 1, or the sheet 2 is adhered to the sheet 2 used for another layer by a large amount of adhesive. The state of being squeezed is not preferable.
This is because the sheet 2 allows sound to pass through appropriately in the equivalent circuit as a sound absorbing material, but plays a role as a mass, and the adjacent non-woven fabric 1 plays a role as an interfering body (spring). This is because if the two layers of each sheet are physically bonded and fixed in some way, the function of the non-woven fabric 1 as a spring is impaired. Further, since the sheet 2 has a through hole in order to allow sound to pass through appropriately, when the sheet 2 is fixed to the non-woven fabric 1 with an adhesive or the like, the sheet 2 can be adhered without blocking the through hole. is important. Examples of the adhesive include acrylic, urethane, silicone, polyvinyl alcohol, vinyl acetate, natural rubber, styrene-butadiene rubber, cyanoacrylate, urea, epoxy, cellulose, and chloroprene rubber. Examples thereof include adhesives and adhesives such as, and other examples include various hot melt adhesives such as modified olefins. Further, the adhesive polymer described above in the description of the non-woven fabric 1 can also be applied. For example, when polyethylene fibers are contained in the non-woven fabric 1 and the non-woven fabric 1 exhibits adhesiveness, a method of coating the surface of the sheet 2 with polyethylene and fixing them by heat fusion can also be used.

For the fiber laminated structure of the present invention, it is preferable to use the same quality material from the viewpoint of cost, performance, handleability, and from the viewpoint of a product that is easy to recycle. For example, by using a combination of a non-woven fabric 1 made of polyester fibers containing a copolymerized polyester and a polyester sheet 2 also containing a copolymerized polyester, chemical recyclability can be expected.

<Characteristics of fiber laminated structure>
By forming the above-mentioned laminated structure, the fiber laminated structure of the present invention can be obtained, but the fiber laminated structure of the present invention has both a low frequency region and a high frequency region even if the total thickness is thin. It develops sound absorption characteristics with a well-balanced sound absorption characteristics. The effect is particularly high when the volume (thickness) occupied by the sound absorbing material is restricted, as in automobile applications. Therefore, in the sense that the effect of the present invention is effectively exhibited, the total thickness is preferably 5 cm or less. It is more preferably 4 cm or less, still more preferably 3 cm or less. The fiber laminated structure of the present invention thus obtained exhibits an effect of appropriately absorbing sound in a relatively low frequency region of about 1000 Hz and sound in a relatively high frequency region of about 3500 Hz at the same time. Examples of the sound in the frequency range of about 1000 Hz include automobile road noise and engine sound, while the sound in the frequency range of around 3500 Hz includes sound such as wind noise. By appropriately absorbing both of these sounds, there is an effect of enhancing comfort in, for example, the inside of an automobile or the interior of a building. More specifically, it is preferable that the reverberation room method sound absorption coefficient at a frequency of 1000 Hz is 0.3 or more and the reverberation room method sound absorption coefficient at a frequency of 3500 Hz is 0.3 or more. More preferably, the reverberation room method sound absorption coefficient at both frequencies is 0.35 or more, and more preferably 0.4 or more.

Next, examples and comparative examples of the fiber laminated structure of the present invention will be described in detail, but the present invention is not limited thereto. Each measurement item in the examples was measured by the following method.
(1) Melting point: Using a differential scanning calorimetry (DSC), the temperature was measured at a heating rate of 20 ° C./min to determine the peak top temperature of the melting peak. When it was difficult to determine the melting peak, a micro melting point measuring device (manufactured by Yanagimoto Seisakusho) was used, and the temperature at which the polymer softened and began to flow (softening point) was used as the melting point. The n number was set to 5, and the average value was calculated.
(2) Number of crimps: Measured by the method described in JIS L 1015 7.12. The n number was set to 5, and it was calculated from the average value.
(3) Metsuke: The basis weight of the non-woven fabric was measured according to JIS L 1096, and the basis weight of the sheet was measured according to JIS K 7130.
(4) Sound absorption characteristics (reverberation room method sound absorption coefficient): Measurement was performed in accordance with ISO 354 Direct Method. In order to eliminate the influence of acoustic sound absorption from the side surface of the sample, the sample was spread in an aluminum frame having an inner size of 1000 mm × 1000 mm, and the measurement was performed.
(5) Total thickness of fiber laminated structure: Measured according to JIS K 6400.
(6) Single yarn fineness: Measured by the method described in JIS L 1015: 2005 8.5.1 A method.

<Manufacturing of non-woven fabric 1-1>
From a core-sheath structure with a single-thread fineness of 2.2 dtex (average fiber diameter of 14.5 μm) and a fiber length of 51 mm, using crystalline copolymer polyester with a melting point of 110 ° C as the sheath component and polyethylene terephthalate with a melting point of 256 ° C as the core component. Adhesive composite fiber (weight ratio of core component / sheath component = 50/50) and single-thread fineness 2.2 dtex (average fiber diameter 14. 5 μm), inelastic crimped short fibers made of polyethylene terephthalate short fibers having a fiber length of 51 mm were mixed so as to have a weight ratio of 25/75, and the fibers were arranged in the vertical direction using roller card equipment and strut equipment, and further. By applying the heat treatment, a non-woven fabric (grain: 269 g / m ² , thickness: 11 mm) was produced.

<Manufacturing of non-woven fabric 1-2>
From a core-sheath structure with a single-thread fineness of 2.2 dtex (average fiber diameter of 14.5 μm) and a fiber length of 51 mm, using crystalline copolymer polyester with a melting point of 110 ° C as the sheath component and polyethylene terephthalate with a melting point of 256 ° C as the core component. Adhesive composite fiber (weight ratio of core component / sheath component = 50/50) and single-thread fineness 0.4 dtex (average fiber diameter 6. 8 μm), inelastic crimped short fibers made of polyethylene terephthalate short fibers having a fiber length of 51 mm were mixed so as to have a weight ratio of 25/75, and the fibers were arranged in the vertical direction using roller card equipment and strut equipment, and further. By applying the heat treatment, a non-woven fabric (grain: 264 g / m ² , thickness: 10 mm) was produced.

<Manufacturing of non-woven fabric 1-3>
From a core-sheath structure with a single-thread fineness of 2.2 dtex (average fiber diameter of 14.5 μm) and a fiber length of 51 mm, using crystalline copolymer polyester with a melting point of 110 ° C as the sheath component and polyethylene terephthalate with a melting point of 256 ° C as the core component. Adhesive composite fiber (weight ratio of core component / sheath component = 50/50) and single-thread fineness of 0.1 dtex (average fiber diameter 3. 1 μm), inelastic crimped short fibers made of polyethylene terephthalate short fibers having a fiber length of 51 mm are mixed so as to have a weight ratio of 25/75, and the fibers are arranged in the vertical direction using roller card equipment and strut equipment, and further. By applying the heat treatment, a non-woven fabric (grain: 265 g / m ² , thickness: 11 mm) was produced.

<Manufacturing of sheet 2-1>
Each polyester of the A layer (surface layer) in which the amount of barium sulfate added is 4% by weight and the B layer (intermediate layer) in which the amount of barium sulfate added is 45% by weight is melted by an extruder at 290 ° C. , A layer / B layer / A layer are merged using a laminated feed block so as to have a three-layer structure. Then, an unstretched film was obtained. At this time, the thickness ratio of the A layer / B layer / A layer was 4/92/4. The obtained unstretched film was stretched 3.3 times in the vertical direction at 95 ° C., and then stretched 3.6 times in the horizontal direction at 120 ° C. using a clip-type tenter. Then, a 225 ° C. constant-length heat set was applied in the tenter. Further, after that, a relaxation treatment of 0.5% in the vertical direction and 2.0% in the horizontal direction was performed, and the film was cooled to room temperature to obtain a biaxially stretched film. The thickness of the obtained film was 188 μm and the basis weight was 265 g / m ² .
A through hole having a hole diameter of 1 mm was provided in the obtained film by laser processing at a pitch of 5 mm in both vertical and horizontal directions to obtain a sheet 2-1 (opening ratio: 3.1%, basis weight: 257 g / m ² ).

<Manufacturing of sheet 2-2>
Nouvelle TR-EL1 (manufactured by Teijin Co., Ltd., a thermoplastic elastomer composed of a copolymer of polytetramethylene glycol and polybutylene terephthalate) at 230 ° C. for an extruder equipped with an inert gas quantitative supply device (manufactured by Plasteco). Sheet 2-, which is a foamed sheet, is extruded from a die and cooled and solidified by a casting drum with a surface temperature of 40 ° C. while supplying nitrogen in a supercritical state to the resin so as to have a compounding ratio of 1.1%. I got 2. The obtained foam sheet had a basis weight of 394 g / m ² , a thickness of 650 μm (bulk density: about 0.62 g / cm ³ ), and an air permeability of 0.20 ^{cm 3} / cm ² · sec.

<Manufacturing of sheets 2-3>
A through hole having a hole diameter of 1.2 mm was provided in the sheet 2-2 at a pitch of 2 mm in both the vertical and horizontal directions, and a sheet 2-3 (opening rate 33.0%, basis weight 264 g / m ² ) was obtained.

<Manufacturing of sheets 2-4>
A through hole having a hole diameter of 1 mm was provided in the sheet 2-2 at a pitch of 2 mm in both vertical and horizontal directions to obtain a ^{sheet 2-4 (opening rate: 19.6%, basis weight: 316 g / m 2).}

<Manufacturing of sheet 2-5>
A through hole having a hole diameter of 1 mm was provided on the sheet 2-2 at a pitch of 5 mm in both vertical and horizontal directions to obtain a ^{sheet 2-5 (opening rate: 3.1%, basis weight: 381 g / m 2).}

<Manufacturing of sheet 2-6>
A through hole having a hole diameter of 0.5 mm was provided in the sheet 2-2 at a pitch of 5 mm in both the vertical and horizontal directions, and a sheet 2-6 (opening rate: 0.8%, basis weight: 389 g / m ² ) was obtained.

<Manufacturing of sheet 2-7>
A through hole having a hole diameter of 0.1 mm was provided in the sheet 2-2 at a pitch of 5 mm in both vertical and horizontal directions to obtain a ^{sheet 2-7 (opening rate: less than 0.1%, basis weight: 392 g / m 2).}

[Example 1]
The non-woven fabric 1-1 and the sheet 2-1 were superposed and heat-pressed at 170 ° C. to obtain a fiber laminated structure having a five-layer structure (sheet / non-woven fabric / sheet / non-woven fabric / sheet). The total thickness of the obtained fiber laminated structure was 21 mm. The sound absorption coefficient of the fiber laminated structure at 1000 Hz was 0.74, and the sound absorption coefficient at 3500 Hz was 0.33.

[Example 2]
The non-woven fabric 1-1 and the sheet 2-4 were superposed and heat-pressed at 170 ° C. to obtain a fiber laminated structure having a five-layer structure (sheet / non-woven fabric / sheet / non-woven fabric / sheet). The total thickness of the obtained fiber laminated structure was 20 mm. The sound absorption coefficient of the fiber laminated structure at 1000 Hz was 0.31, and the sound absorption coefficient at 3500 Hz was 0.74.

[Example 3]
The non-woven fabric 1-1 and the sheet 2-4 were superposed and heat-pressed at 170 ° C. to obtain a fiber laminated structure having a three-layer structure (sheet / non-woven fabric / sheet). The total thickness of the obtained fiber laminated structure was 11 mm. The sound absorption coefficient of the fiber laminated structure at 1000 Hz was 0.40, and the sound absorption coefficient at 3500 Hz was 0.56.

[Example 4]
The non-woven fabric 1-1 and the sheet 2-5 were superposed and heat-pressed at 170 ° C. to obtain a fiber laminated structure having a five-layer structure (sheet / non-woven fabric / sheet / non-woven fabric / sheet). The total thickness of the obtained fiber laminated structure was 20 mm. The sound absorption coefficient of the fiber laminated structure at 1000 Hz was 0.49, and the sound absorption coefficient at 3500 Hz was 0.51.

[Example 5]
By superimposing the non-woven fabric 1-1 and the sheet 2-4 and heat-pressing at 170 ° C., a fiber laminated structure having a 7-layer structure (sheet / non-woven fabric / sheet / non-woven fabric / sheet / non-woven fabric / sheet) was obtained. .. The total thickness of the obtained fiber laminated structure was 32 mm. The sound absorption coefficient of the fiber laminated structure at 1000 Hz was 0.47, and the sound absorption coefficient at 3500 Hz was 0.48.

[Example 6]
The non-woven fabric 1-1 and the sheet 2-6 were superposed and heat-pressed at 170 ° C. to obtain a fiber laminated structure having a five-layer structure (sheet / non-woven fabric / sheet / non-woven fabric / sheet). The total thickness of the obtained fiber laminated structure was 21 mm. The sound absorption coefficient of the fiber laminated structure at 1000 Hz was 0.88, and the sound absorption coefficient at 3500 Hz was 0.63.

[Example 7]
The non-woven fabric 1-2 and the sheet 2-6 were superposed and heat-pressed at 170 ° C. to obtain a fiber laminated structure having a five-layer structure (sheet / non-woven fabric / sheet / non-woven fabric / sheet). The total thickness of the obtained fiber laminated structure was 20 mm. The sound absorption coefficient of the fiber laminated structure at 1000 Hz was 0.71, and the sound absorption coefficient at 3500 Hz was 0.51.

[Example 8]
The non-woven fabric 1-3 and the sheet 2-5 were superposed and heat-pressed at 170 ° C. to obtain a fiber laminated structure having a three-layer structure (sheet / non-woven fabric / sheet). The total thickness of the obtained fiber laminated structure was 10 mm. The sound absorption coefficient of the fiber laminated structure at 1000 Hz was 0.59, and the sound absorption coefficient at 3500 Hz was 0.76.

[Example 9]
The non-woven fabric 1-3 and the sheet 2-5 were superposed and heat-pressed at 170 ° C. to obtain a fiber laminated structure having a five-layer structure (sheet / non-woven fabric / sheet / non-woven fabric / sheet). The total thickness of the obtained fiber laminated structure was 20 mm. The sound absorption coefficient of the fiber laminated structure at 1000 Hz was 0.62, and the sound absorption coefficient at 3500 Hz was 0.84.

[Example 10]
By superimposing the non-woven fabric 1-3 and the sheet 2-5 and heat-pressing at 170 ° C., a fiber laminated structure having a 7-layer structure (sheet / non-woven fabric / sheet / non-woven fabric / sheet / non-woven fabric / sheet) was obtained. .. The total thickness of the obtained fiber laminated structure was 29 mm. The sound absorption coefficient of the fiber laminated structure at 1000 Hz was 0.65, and the sound absorption coefficient at 3500 Hz was 0.76.

[Example 11]
The non-woven fabric 1-3 and the sheet 2-6 were superposed and heat-pressed at 170 ° C. to obtain a fiber laminated structure having a five-layer structure (sheet / non-woven fabric / sheet / non-woven fabric / sheet). The total thickness of the obtained fiber laminated structure was 21 mm. The sound absorption coefficient of the fiber laminated structure at 1000 Hz was 0.77, and the sound absorption coefficient at 3500 Hz was 0.55.

[Comparative Example 1]
The non-woven fabric 1-1 and the sheet 2-3 were overlapped and hot-pressed at 170 ° C. to obtain a fiber laminated structure having a five-layer structure (sheet / non-woven fabric / sheet / non-woven fabric / sheet). The total thickness of the obtained fiber laminated structure was 22 mm. The sound absorption coefficient of the fiber laminated structure at 1000 Hz was 0.22, and the sound absorption coefficient at 3500 Hz was 0.44.

[Comparative Example 2]
The non-woven fabric 1-1 and the sheet 2-5 were superposed and heat-pressed at 170 ° C. to obtain a fiber laminated structure having a two-layer structure (sheet / non-woven fabric). The total thickness of the obtained fiber laminated structure was 10 mm. The sound absorption coefficient of the fiber laminated structure at 1000 Hz was 0.22, and the sound absorption coefficient at 3500 Hz was 0.44.

[Comparative Example 3]
The non-woven fabric 1-3 and the sheet 2-7 were superposed and heat-pressed at 170 ° C. to obtain a fiber laminated structure having a five-layer structure (sheet / non-woven fabric / sheet / non-woven fabric / sheet). The total thickness of the obtained fiber laminated structure was 10 mm. The sound absorption coefficient of the fiber laminated structure at 1000 Hz was 0.72, and the sound absorption coefficient at 3500 Hz was 0.12.

The main configurations of the fiber laminated structures of Examples 1 to 11 and Comparative Examples 1 to 3 and the evaluation results of the sound absorption coefficient are summarized in the following table.

Although the fiber laminated structure of the present invention is thin and has shapeability, it is excellent in acoustic sound absorption performance from low frequency to high frequency, so that it can be suitably used as a sound absorbing material in various applications. Is. In particular, it is particularly effective for mobility applications such as automobiles, railroad vehicles, and aircraft, which have many physical restrictions such as space and weight.

Claims (5)

Non-woven fabric with a basis weight of 800 g / m ² or less and a sheet having a through hole with a basis weight of 70 g / m ² or more are alternately laminated, and the area of one side of the sheet having a through hole with a ^{basis weight of 70 g / m 2 or more.} A fiber laminated structure in which the area ratio of the through-holes to the above-mentioned is 0.1 to 20%, and at least two or more sheets having the through-holes are contained. The fiber laminated structure according to claim 1, wherein the reverberation room method sound absorption coefficient of 1000 Hz is 0.3 or more and the reverberation room method sound absorption coefficient of 3500 Hz is 0.3 or more. The fiber laminated structure according to claim 1 or 2, wherein the fibers constituting the non-woven fabric contain fibers having a single yarn fineness of 1.0 dtex or less. The fiber according to any one of claims 1 to 3 ^{, wherein a sheet having a through hole having a basis weight of 70 g / m 2} or more is arranged at at least one end of the fiber laminated structure in the laminating direction. Laminated structure. The fiber-laminated structure according to any one of claims 1 to 4, wherein the total thickness of the fiber-laminated structure is 5 cm or less.