Nonwoven fabric laminate for sound absorbing material and sound absorbing material

Abstract

This invention provides a nonwoven laminate for sound-absorbing materials and a sound-absorbing material with excellent thickness recovery and conformability during forming, as well as excellent sound absorption performance. The sound-absorbing material is a nonwoven fabric laminate composed of nonwoven fabric layer α and nonwoven fabric layer β. Nonwoven fabric layer α contains short fibers A with a fineness of 0.4 dtex to 3.8 dtex, short fibers B with a fineness of 4.0 dtex to 22.0 dtex, and short fibers C1 containing resin with a melting point of 135℃ to 190℃ in the outer surface layer. The total mass of short fibers A and B relative to the total mass of nonwoven fabric layer α is 86% to 98% by mass, and the mass of short fibers C1 relative to the total mass of nonwoven fabric layer α is 2% to 14% by mass. The mass ratio of short fibers A to short fibers B is 0.05 to 3.80. Nonwoven fabric layer β contains short fibers C2 containing resin with a melting point of 70℃ to 190℃ in the outer surface layer. The mass of short fibers C2 relative to the total mass of nonwoven fabric layer β is 20% to 60% by mass. Nonwoven fabric layer α and nonwoven fabric layer β are partially fused together.

Description

Technical Field

[0001] This invention relates to a nonwoven fabric for sound-absorbing materials and a sound-absorbing material. Background Technology

[0002] In recent years, noise reduction has become more important than ever as a commodity value in products such as automobiles and electrical appliances. While increasing the quality and thickness of sound-absorbing materials is often effective in addressing noise, from the perspective of maximizing space in car cabins or living rooms, or reducing fuel consumption in automobiles, there is a demand for lightweight and compact sound-absorbing materials. Furthermore, in automobiles, techniques are often used to shape sound-absorbing materials into the form of components through molding processes, allowing the materials to conform to the complex shapes of the car body and be compactly installed.

[0003] Patent document 1 discloses a molded article for sound-absorbing material, which is formed by closing a composite material using a molding die. The composite material includes a substrate containing non-woven fabric or resin foam and a skin material.

[0004] In addition, Patent Document 2 proposes a sound-absorbing material comprising a fiber assembly containing high softening point synthetic staple fibers with a denier of 1.5 denier to 20 denier, medium softening point synthetic staple fibers with a denier of 1.5 denier to 15 denier, and low softening point synthetic staple fibers with a denier of 1.5 denier to 15 denier.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2012-24955

[0008] Patent Document 2: Japanese Patent Application Publication No. 10-245755 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] According to the inventors' understanding, the molded article for sound-absorbing material disclosed in Patent Document 1 is formed by heating a nonwoven fabric containing low-melting-point filaments, and therefore it is easy to give it a shape through molding. However, when the low-melting-point filaments have a low melting point and contain a large mass, the thickness after molding becomes thin due to the adhesive effect when the low-melting-point filaments melt and then solidify, resulting in poor sound absorption performance.

[0011] On the other hand, the sound-absorbing material disclosed in Patent Document 2 contains high-softening-point synthetic fiber short fibers, thus exhibiting a tendency to improve heat resistance in the event of a temperature rise inside the vehicle compartment. However, with a high content of medium-softening-point synthetic fiber short fibers, the thickness becomes thinner after molding and processing due to melting and bonding, resulting in a decrease in sound absorption performance.

[0012] Furthermore, during the molding process, the surface of the sound-absorbing material is prone to abrasion or cracking due to friction between the nonwoven fabric and the mold. Therefore, in view of the above situation, the present invention aims to provide a nonwoven fabric laminate for sound-absorbing materials that has good sinking rebound force during molding, excellent thickness recovery, excellent molding conformity to complex shapes such as automobile bodies, and thus excellent sound absorption performance.

[0013] Technical means to solve the problem

[0014] (1) A nonwoven fabric laminate for sound-absorbing materials, comprising a nonwoven fabric layer α and a nonwoven fabric layer β laminated together, wherein the nonwoven fabric layer α contains short fibers A with a fineness of 0.4 dtex to 3.8 dtex, short fibers B with a fineness of 4.0 dtex to 22.0 dtex, and short fibers C1 containing a resin with a melting point of 135°C to 190°C in the outer surface layer, wherein the total mass of the short fibers A and B relative to the total mass of the nonwoven fabric layer α is 86% to 98% by mass. The short fiber C1 contains 2% to 14% of the total mass of the nonwoven layer α, the mass ratio of the short fiber A to the short fiber B (mass content of short fiber A / mass content of short fiber B) is 0.05 to 3.80, the nonwoven layer β contains short fiber C2 with a resin having a melting point of 70°C to 190°C in its outer surface layer, the short fiber C2 contains 20% to 60% of the total mass of the nonwoven layer β, and the nonwoven layer α and the nonwoven layer β are partially fused together.

[0015] (2) The nonwoven fabric laminate for sound-absorbing material according to (1), wherein the short fiber C1 is a core-sheath type composite short fiber, and the resin constituting the sheath is a thermoplastic resin with a melting point of 135°C to 190°C.

[0016] (3) The nonwoven laminate for sound-absorbing material according to (1) or (2), wherein the fineness of the short fiber C1 is 1.0 dtex to 5.0 dtex.

[0017] (4) The nonwoven laminate for sound-absorbing material according to any one of (1) to (3), wherein the thermoplastic resin with a melting point of 135°C to 190°C is a crystalline resin.

[0018] (5) The nonwoven laminate for sound-absorbing material according to any one of (1) to (4), wherein the short fiber C2 is a core-sheath type composite short fiber, and the resin constituting the sheath is a thermoplastic resin with a melting point of 70°C to 190°C.

[0019] (6) The nonwoven laminate for sound-absorbing material according to any one of (1) to (5), wherein the thermoplastic resin with a melting point of 70°C to 190°C is a non-crystalline resin.

[0020] (7) A nonwoven fabric laminate for sound-absorbing material according to any one of (1) to (6), wherein the unit area weight of the nonwoven fabric layer α is 100 g / m². 2 Above and 700g / m 2 Hereinafter, the thickness of the nonwoven fabric layer α is 7 mm or more and 40 mm or less.

[0021] (8) A nonwoven laminate for sound-absorbing material according to any one of (1) to (7), wherein the nonwoven layer β has a unit area weight of 30 g / m². 2 Above and 120g / m 2 the following.

[0022] (9) A nonwoven laminate for sound-absorbing material according to any one of (1) to (8), wherein the nonwoven layer β has a tensile elongation at break of 50% or more and a static friction coefficient of 0.5 or less.

[0023] (10) The nonwoven fabric for sound-absorbing material according to any one of (1) to (9), wherein the short fiber A, the short fiber B, the short fiber C1 and the short fiber C2 are all polyester short fibers.

[0024] (11) A sound-absorbing material, wherein the sound-absorbing material according to any one of (1) to (10) is used as a non-woven fabric laminate as a substrate, and further has an air permeability of 3 cm. 3 / cm 2 / s~50cm 3 / cm 2 / s of the skin nonwoven fabric layer γ, which is laminated on the surface of the nonwoven fabric layer α side of the sound-absorbing material nonwoven fabric laminate.

[0025] The effects of the invention

[0026] This invention provides a nonwoven fabric for sound-absorbing materials that exhibits excellent thickness recovery during molding, excellent conformability to complex shapes such as car bodies, and consequently, excellent sound absorption performance. Furthermore, it provides a sound-absorbing material with a nonwoven fabric for sound-absorbing materials as the substrate and a nonwoven fabric outer layer. Detailed Implementation

[0027] In the nonwoven fabric laminate for sound-absorbing material of the present invention, nonwoven fabric layer α and nonwoven fabric layer β are laminated. Nonwoven fabric layer α contains short fibers A with a fineness of 0.4 dtex to 3.8 dtex and short fibers B with a fineness of 4.0 dtex to 22.0 dtex. The total mass content of short fibers A and B relative to the total mass of nonwoven fabric layer α is 86% to 98% by mass, and the mass ratio of short fibers A to short fibers B (mass content of short fibers A / mass content of short fibers B) is 0.05 to 3.80. Furthermore, nonwoven fabric layer α contains short fibers C1, the outer surface of which contains a resin with a melting point of 135°C to 190°C. The mass content of short fibers C1 relative to the total mass of nonwoven fabric layer α is 2% to 14% by mass. The nonwoven layer β contains short fibers C2, which contain resin with a melting point of 70°C to 190°C, and the content of short fibers C2 relative to the total mass of the nonwoven layer β is 20% to 60% by mass.

[0028] The nonwoven layer α is part of the substrate of the sound-absorbing material, and short fibers A, B, and C1 are uniformly mixed in. The presence of short fiber A creates numerous fine pores, resulting in excellent sound absorption performance. Furthermore, short fiber B, with a finer fiber density than short fiber A, also creates numerous fine pores and exhibits high rigidity, which contributes to thickness recovery during molding. By adjusting the mass ratio of short fiber A to short fiber B and ensuring their uniform mixing, both sound absorption performance and thickness recovery during molding are achieved.

[0029] That is, this sound-absorbing material uses a non-woven fabric laminate (hereinafter, sometimes simply referred to as "non-woven fabric") through a non-woven fabric layer α having the aforementioned structure, thereby exhibiting excellent thickness recovery during heating or compression during molding. Moreover, the sound-absorbing material ensures the thickness required to achieve its sound-absorbing performance, and its sound-absorbing performance becomes excellent through air friction from the fine porous parts inside the non-woven fabric layer α.

[0030] Furthermore, by having the nonwoven layer β with the aforementioned structure, the breakage of the nonwoven layer caused by friction between the nonwoven laminate of sound-absorbing material and the forming mold can be suppressed during heating or compression during forming. This results in excellent mold conformability, enabling the material to be formed into the desired shape. Moreover, the nonwoven layer β only needs to be located on at least one side of the nonwoven layer α, or it can be located on both sides. Regarding the sound-absorbing material, during the forming process, the skin material (described later) is included on the other side of the nonwoven layer α. Therefore, by having the nonwoven layer β on one side in contact with the forming mold, breakage of the nonwoven layer can be suppressed, resulting in excellent mold conformability and enabling the material to be formed into the desired shape.

[0031] Here, if the content of short fiber C1 in nonwoven layer α is increased, the resin content contained in the short fiber C1 inside nonwoven layer α increases. Due to the adhesive effect of the resin melting and re-curing at 135℃~190℃, the thickness becomes thinner during molding and processing, making it difficult to obtain thickness recovery. Therefore, in this invention, by suppressing the content of short fiber C1 in nonwoven layer α and increasing the content of short fiber C2 in nonwoven layer β, a nonwoven fabric for sound-absorbing materials with good thickness recovery during molding and processing and excellent sound absorption performance can be obtained.

[0032] Then, nonwoven layer α and nonwoven layer β are laminated together, and their interfaces are partially fused together to obtain a nonwoven laminate. The so-called "partial fusion" of nonwoven layer α and nonwoven layer β refers to melting the resin contained in the outer layer of short fibers C2 contained in nonwoven layer β, causing a portion of short fibers A, B, or C1 of nonwoven layer α to bond with short fibers C2 and other short fibers of nonwoven layer β. That is, the resin binds the fibers together at the points where single fibers intersect, and the bonding is partial rather than a complete bonding of the laminated surfaces.

[0033] Regarding the interface between nonwoven layer α and nonwoven layer β, it is important that the lamination state of nonwoven layer α and nonwoven layer β remains unchanged during molding. If the lamination state changes, the nonwoven layers may peel off or stack during molding, making it difficult to maintain sound absorption performance. Therefore, for nonwoven layer β, in addition to suppressing the breakage of the sound-absorbing nonwoven material caused by friction between the nonwoven material and the molding die during heating or compression during molding, it is also necessary to maintain the lamination state. The short fibers C2 contained in nonwoven layer β partially bond the short fibers of the laminated nonwoven layers α and β to each other. Therefore, it is preferable that the melting point of the resin contained in the outer layer of the short fibers C2 contained in nonwoven layer β is lower than the melting point of the resin contained in the outer layer of the short fibers C1.

[0034] The nonwoven layer α contains short fibers A with a fineness of 0.4 dtex to 3.8 dtex and short fibers B with a fineness of 4.0 dtex to 22.0 dtex. By containing short fibers A with a fineness of 0.4 dtex to 3.8 dtex, a porous structure with numerous micropores can be formed inside the nonwoven fabric for sound absorption, resulting in excellent sound absorption performance of the sound-absorbing material using the nonwoven fabric.

[0035] By setting the fineness of short fiber A to 0.4 dtex or more, fiber breakage or entanglement with the carding fabric is suppressed during the carding process in manufacturing the nonwoven layer α. This allows short fiber A to be uniformly dispersed within the nonwoven layer α, forming a porous portion with numerous fine pores within the layer, resulting in excellent sound absorption performance when used as a sound-absorbing material. Conversely, by setting the fineness of short fiber A to 3.8 dtex or less, a porous portion with numerous fine pores can be formed within the nonwoven layer α using short fibers with a small fineness. Consequently, when sound passes through the gaps between the fibers, i.e., the porous portion, the sound is efficiently converted into heat through friction with the air around the fibers, resulting in excellent sound absorption when used as a sound-absorbing material. In this respect, the fineness of short fiber A is preferably 0.5 dtex to 2.0 dtex, and more preferably 0.5 dtex to 0.9 dtex.

[0036] Furthermore, the nonwoven layer α included in the nonwoven laminate of the present invention contains short fibers B with a fineness of 4.0 dtex to 22.0 dtex, thereby imparting thickness recovery during forming to the nonwoven fabric of the present invention through the rigidity of the short fibers B. By setting the fineness of the short fibers B to 4.0 dtex or more, the nonwoven fabric of the present invention can be imparted with thickness recovery during forming through the rigidity of the short fibers B. On the other hand, by setting the fineness of the short fibers B to 22.0 dtex or less, a porous portion with a large number of fine pores can be formed inside the nonwoven layer α, resulting in excellent sound absorption performance when made into a sound-absorbing material. In this respect, the fineness of the short fibers B is preferably 5.0 dtex to 18.0 dtex, and particularly preferably 6.0 dtex to 15.0 dtex.

[0037] The nonwoven layer α included in the nonwoven laminate of the present invention has the following characteristics: the total mass content of short fibers A and B relative to the total mass of the nonwoven layer α is 86% to 98% by mass, and the mass ratio of short fibers A to short fibers B (mass content of short fibers A / mass content of short fibers B) is 0.05 to 3.80. By setting the total content of short fibers A and B and their mass ratio within the aforementioned range, both thickness recovery during forming and sound absorption performance when made into a sound-absorbing material can be considered. By setting the total mass content of short fibers A and B to 86% by mass or more, excessive bonding between fibers caused by the short fibers C1 described later can be suppressed, and thickness recovery can be maintained even during heating or compression during forming. As a result, a thickness for sound absorption performance is formed, i.e., a porous part with fine pores is formed inside the nonwoven layer α, resulting in excellent sound absorption performance. On the other hand, by setting the total mass content of short fibers A and B to 98% by mass or less, the form of the nonwoven layer α can be maintained, enabling the conveying or handling of the nonwoven fabric for sound absorption material during forming processes. This further reduces fiber shedding when cutting the sound absorption material. In this respect, the total mass content of short fibers A and B is preferably 86% to 97% by mass, and particularly preferably 90% to 97% by mass.

[0038] Furthermore, by setting the mass ratio of short fiber A to short fiber B (mass content of short fiber A / mass content of short fiber B) to 0.05–3.80, both thickness recovery during molding and sound absorption performance when made into sound-absorbing materials can be considered. The nonwoven layer α is composed of a material premixed with short fibers A, B, and C1. Therefore, it is not a layer structure containing specific short fibers, but rather a nonwoven fabric in which each constituent fiber is uniformly dispersed within the nonwoven layer α.

[0039] Therefore, short fiber A enhances sound absorption performance by forming fine porous components within the nonwoven layer α. Additionally, short fiber B imparts thickness recovery during forming due to its rigidity. By setting the mass ratio of short fiber A to short fiber B to 0.05 or more, fine porous components can be formed within the nonwoven layer α, improving sound absorption performance. Conversely, by setting the mass ratio of short fiber A to short fiber B to 3.80 or less, the rigidity of short fiber B imparts thickness recovery during forming, creating a thickness—i.e., a porous component—that provides sound absorption performance. Furthermore, by including relatively coarse short fiber B at a certain mass ratio, even when short fiber A is fine, fiber breakage or entanglement into the carding fabric during the carding process is suppressed. The short fiber A is uniformly dispersed, forming fine porous components within the nonwoven layer α, resulting in excellent sound absorption performance when the material is made from it. In this respect, the mass ratio of short fiber A to short fiber B is preferably 0.20 to 2.20, and particularly preferably 0.30 to 1.40.

[0040] The nonwoven layer α included in the nonwoven laminate of the present invention has the following characteristics: it contains short fibers C1 comprising a resin with a melting point of 135°C to 190°C, and the content of the short fibers C1 relative to the total mass of the nonwoven layer α is 2% to 14% by mass. By setting the melting point of the resin contained in the short fibers C1 and the content of the short fibers C1 within the aforementioned range, it is possible to balance thickness recovery during molding, handling or transport of the nonwoven fabric for sound-absorbing materials, and reduction of fiber shedding when cutting the sound-absorbing material. By setting the melting point of the resin contained in the short fibers C1 to 135°C or higher, the welding of the constituent fibers of the nonwoven layer α caused by the short fibers C1 can be suppressed during the manufacturing stage of the nonwoven layer α, and thickness recovery can be maintained even during heating or compression during molding. On the other hand, by setting the melting point of the resin contained in the short fiber C1 to below 190°C, during the manufacturing stage of the nonwoven layer α, the welding of the constituent fibers of the nonwoven layer α caused by the short fiber C1 can reduce the handling or maneuverability of the nonwoven fabric for sound-absorbing materials, and further reduce fiber shedding when cutting the sound-absorbing material. In this respect, the melting point of the resin contained in the short fiber C1 is preferably 140°C to 180°C, and particularly preferably 145°C to 170°C.

[0041] Furthermore, by setting the content of short fiber C1 relative to the total mass of nonwoven layer α to 2% by mass or more, the welding of the constituent fibers of nonwoven layer α caused by short fiber C1 during the manufacturing stage of nonwoven layer α can reduce the handling or maneuverability of the nonwoven fabric for sound-absorbing material, and further reduce fiber shedding when cutting the sound-absorbing material. On the other hand, by setting the content of short fiber C1 relative to the total mass of nonwoven layer α to 14% by mass or less, the welding point of short fiber C1 and short fiber A, or the welding point of short fiber C1 and short fiber B during heating or compression during forming can be reduced, and the thickness recovery can be maintained even during heating or compression during forming. In this respect, the content of short fiber C1 relative to the total mass of nonwoven layer α is preferably 3% to 12% by mass, and particularly preferably 3% to 10% by mass.

[0042] The nonwoven layer β included in the nonwoven laminate of the present invention has the following characteristics: it contains short fibers C2, which have a resin with a melting point of 70°C to 190°C in the outer surface layer, and the content of short fibers C2 relative to the total mass of the nonwoven layer β is 20% to 60% by mass. There is no particular specification for the fibers of short fibers C2, and known fibers can be used, such as side-by-side composite fibers formed by bonding low-melting-point components with high-melting-point components, or core-sheath composite fibers formed by coating high-melting-point components with low-melting-point components.

[0043] The nonwoven layer β contains 40% to 80% by mass of other short fibers. Regarding the raw materials for these other short fibers, thermoplastic resins such as polyester resins, polyamide resins, acrylic resins, and polyolefin resins can be used. Among these, short fibers containing polyester resins are preferred in terms of excellent heat resistance, which reduces deformation or discoloration of the sound-absorbing nonwoven fabric in high-temperature environments when used near the engine room of automobiles, etc.

[0044] By setting the melting point of the resin in the outer layer contained in the short fiber C2 and the mass of the short fiber C2 within the aforementioned range, the smoothness of the nonwoven layer β is increased, which can suppress the breakage of the sound-absorbing nonwoven fabric caused by friction between the sound-absorbing nonwoven fabric and the forming mold during molding, and can be formed into the desired shape. Furthermore, in the manufacturing process of the sound-absorbing nonwoven fabric, the nonwoven layer α and the nonwoven layer β can be easily bonded, which can improve productivity. By setting the melting point of the resin contained in the short fiber C2 to 70°C or higher, the adhesion of resin with a melting point of 70°C to 190°C to the manufacturing apparatus during the manufacturing process of the nonwoven layer β can be eliminated, which can improve productivity. On the other hand, by setting the melting point of the resin contained in the short fiber C2 to below 190°C, the smoothness of the nonwoven layer β can be improved by the fusion of fibers caused by the short fiber C2 during the manufacturing stage. This can suppress the cracking of the sound-absorbing nonwoven fabric caused by friction between the sound-absorbing nonwoven fabric and the forming mold during heating or compression during molding.

[0045] It is speculated that, compared to nonwoven layer α, nonwoven layer β has a lower weight per unit area and fewer fluffy fibers. The resin on the outer layer of short fibers C2 melts and blocks the unevenness of the nonwoven surface, resulting in a smooth surface. In this respect, the melting point of the resin contained in short fibers C2 is preferably 70°C to 180°C, and particularly preferably in the range of 70°C to 170°C. Furthermore, by setting the content of short fibers C2 relative to the total mass of nonwoven layer β to 20% by mass or more, the nonwoven layer β becomes smooth through the fusion of fibers caused by short fibers C2. This suppresses the breakage of the sound-absorbing nonwoven fabric caused by friction between the sound-absorbing nonwoven fabric and the forming mold during heating or compression during molding. Moreover, in the manufacturing process of the sound-absorbing nonwoven fabric laminate, the fusion of short fibers C2 and the short fibers contained in nonwoven layer α can easily fuse nonwoven layer α and nonwoven layer β, improving productivity. On the other hand, by setting the content of the short fiber C2 relative to the total mass of the nonwoven layer β to 60% by mass or less, the tensile elongation at break of the nonwoven layer β can be improved, the following ability of the nonwoven layer β to the forming die can be improved, and the breakage of the nonwoven layer β can be suppressed. In this respect, the content of the short fiber C2 relative to the total mass of the nonwoven layer β is preferably 25% to 50% by mass, and more preferably 25% to 40% by mass. Furthermore, the smoothness can be determined by the static friction coefficient based on the tilting method of Japanese Industrial Standards (JIS) P8147:1994 3.2.

[0046] If the static friction coefficient of the face side of the nonwoven layer β, which is part of the nonwoven laminate, exceeds 0.5, the friction between the sound-absorbing material nonwoven fabric and the forming mold will increase during heating or compression during forming, resulting in wrinkles or cracks on the nonwoven fabric surface, and deteriorating the sound absorption performance or quality. Therefore, this is not preferred. Thus, a static friction coefficient of 0.5 or less is preferred.

[0047] Furthermore, in the nonwoven fabric laminate of the present invention, the short fibers C1 contained in the nonwoven fabric layer α are core-sheath type composite short fibers, and the resin constituting the sheath is preferably a resin with a melting point of 135°C to 190°C. In addition, the sheath of the core-sheath type composite short fiber corresponds to the outer surface layer. By setting the short fibers C1 as core-sheath type composite fibers and through the adhesive effect of the resin contained in the sheath, the fibers contained in the nonwoven fabric layer α can be bonded together. Furthermore, by setting the melting point of the resin constituting the sheath to 135°C or higher, excessive bonding between fibers caused by the short fibers C1 can be suppressed, and the thickness recovery can be improved even during heating or compression during molding. On the other hand, by setting the melting point of the resin constituting the sheath to 190°C or lower, during the manufacturing stage of the nonwoven fabric layer α, the bonding between fibers caused by the short fibers C1 can reduce the handling or maneuverability of the nonwoven fabric for sound-absorbing materials, and further reduce fiber shedding when cutting the sound-absorbing material. In this respect, the melting point of the resin constituting the sheath is preferably 140°C to 180°C, and particularly preferably 145°C to 170°C.

[0048] Furthermore, the fineness of the short fiber C1 is preferably 1.0 dtex to 5.0 dtex. By setting the fineness of the short fiber C1 to 1.0 dtex or more, breakage of the short fiber C1 or its winding into the carding cloth is suppressed during the carding process when manufacturing the nonwoven layer α. The short fiber C1 is evenly dispersed, and the fusion of fibers caused by the short fiber C1 reduces the handling or manipulation of the nonwoven fabric for sound-absorbing materials, and further reduces fiber shedding when cutting the sound-absorbing material. On the other hand, by setting the fineness of the short fiber C1 to 5.0 dtex or less, the fusion points between the short fiber C1 and short fiber A or short fiber B can be increased, reducing the handling or manipulation of the nonwoven fabric for sound-absorbing materials, and further reducing fiber shedding when cutting the sound-absorbing material. In this respect, the fineness of the short fiber C1 is preferably 1.4 dtex to 4.0 dtex, and particularly preferably 1.6 dtex to 3.0 dtex.

[0049] Furthermore, when the short fiber C1 is a core-sheath type composite short fiber and the resin constituting the sheath is a thermoplastic resin with a melting point of 135°C to 190°C, a crystalline resin is preferred. By setting the resin contained in the short fiber C1 to a crystalline thermoplastic resin, even if the content of short fiber C1 is as low as 2% to 14% by mass relative to the total mass of the nonwoven layer α, the fusion between the crystalline resin and short fiber A or short fiber B becomes stronger, reducing the handling or maneuverability of the nonwoven fabric for sound-absorbing materials and preventing fiber shedding when cutting the sound-absorbing material. In addition, as mentioned above, since the content of short fiber C1 can be reduced, the fusion point between short fiber C1 and short fiber A or short fiber B during heating or compression during molding can be reduced, and the thickness recovery can be maintained even during heating or compression during molding. Polyester copolymer resins are preferably listed as such crystalline resins.

[0050] Furthermore, the so-called crystalline resin in this invention refers to a resin that has a glass transition point, a pyrogenic peak based on crystallization (crystallization point), and an endothermic peak based on melting in differential scanning thermal analysis, and is defined as a crystalline resin, while a resin that does not have a clear endothermic peak based on melting at the glass transition point is defined as an amorphous resin.

[0051] On the other hand, the short fiber C2 is preferably a core-sheath type composite short fiber, and the resin constituting the sheath is a thermoplastic resin with a melting point of 70°C to 190°C. Furthermore, the sheath of the core-sheath type composite short fiber corresponds to the outer surface layer. The resin constituting the sheath is a thermoplastic resin with a melting point of 70°C to 190°C, preferably a non-crystalline resin. Polyester copolymer resins are preferably listed as such non-crystalline resins.

[0052] Regarding the raw materials for short fibers A, B, C1, and C2 of the present invention, thermoplastic resins such as polyester resins, polyamide resins, acrylic resins, and polyolefin resins can be used. Among these, short fibers containing polyester resins (hereinafter referred to as polyester short fibers) are preferred in terms of excellent heat resistance, which reduces deformation or discoloration of nonwoven fabrics used as sound-absorbing materials near engine compartments of automobiles, etc., under high-temperature environments. Furthermore, regarding short fibers A and B, short fibers containing polyethylene terephthalate resin (hereinafter referred to as polyethylene terephthalate short fibers) that exhibit excellent heat resistance are particularly preferred among polyester resins.

[0053] The unit area weight of the nonwoven layer α in this invention is preferably 100 g / m². 2 Above and 700g / m 2 The thickness of the nonwoven layer α is preferably 7 mm or more and 40 mm or less. This is achieved by setting the unit area weight of the nonwoven layer α to 100 g / m². 2The above demonstrates that even during heating or compression during forming, the thickness resilience can be improved, and numerous porous sections with fine pores are formed within the nonwoven layer α, resulting in excellent sound absorption performance. Furthermore, by setting the unit area weight of the nonwoven layer α to 700 g / m²... 2 The following describes the production of nonwoven fabrics for sound absorption materials that exhibit excellent lightweight properties. In this regard, the area weight of the nonwoven layer α is preferably 150 g / m². 2 Above and 550g / m 2 The following is particularly preferred: 200g / m 2 Above and 400g / m 2 Furthermore, by setting the thickness of the nonwoven layer α to 7 mm or more, the thickness recovery can be improved even during heating or compression during forming. On the other hand, by setting the thickness of the nonwoven layer α to 40 mm or less, the conveying efficiency of the nonwoven fabric for sound absorption materials and the handling efficiency during forming can be easily improved. In this respect, the thickness of the nonwoven layer α is preferably 10 mm or more and 35 mm or less, and particularly preferably 15 mm or more and 30 mm or less.

[0054] The preferred unit area weight of the nonwoven layer β is 30 g / m². 2 Above and 120g / m 2 The following is an example of setting the unit area weight of the nonwoven layer β to 30 g / m². 2 The above can improve the smoothness of the nonwoven layer β, and suppress the breakage of the sound-absorbing nonwoven fabric caused by friction between the nonwoven fabric and the forming mold during heating or compression during molding. On the other hand, by setting the unit area weight of the nonwoven layer β to 120 g / m²... 2 The following describes the production of nonwoven fabrics for sound absorption materials that exhibit excellent lightweight properties. In this regard, the area weight of the nonwoven layer β is preferably 40 g / m². 2 Above and 100g / m 2 The following is particularly preferred: 45g / m 2 Above and 80g / m 2 the following.

[0055] The tensile elongation at break of the nonwoven layer β is preferably 50% or more. By setting the tensile elongation at break to 50% or more, the following ability of the nonwoven layer β to the forming die can be improved, and the breakage of the nonwoven layer β can be suppressed. In this respect, the tensile elongation at break is preferably 55% or more, and more preferably 60% or more. Regarding the method of improving the tensile elongation at break of the nonwoven layer β, the method of adjusting the content of short fiber C2 as described above can be used, or the method of increasing the interweaving of the short fibers contained in the nonwoven layer β by using a needle punching process or a hydroentangling process during the manufacture of the nonwoven layer β can be used. In addition, the tensile elongation at break of the present invention can be measured according to JIS L 1913:1998 6.3.1, and the average value of the tensile elongation at break in any direction and the direction orthogonal to the arbitrary direction can be calculated.

[0056] Next, a preferred manufacturing method for the nonwoven fabric used in the manufacture of the sound-absorbing material of the present invention will be described. The preferred manufacturing method for the nonwoven fabric of the present invention includes the following steps.

[0057] <Non-woven layer α>

[0058] (a) The process of opening short fibers A, B and C1

[0059] (b) The process of forming short fibers A, B and C1 into sheet form.

[0060] <Non-woven fabric layer β>

[0061] (c) The process of opening short fibers C2 and other short fibers

[0062] (d) Process of forming short fiber C2 and other short fibers into sheet form

[0063] (e) A process of obtaining nonwoven layer β by interlacing short fibers C2 with other short fibers through needles or water flow.

[0064] <Non-woven fabric laminate for sound-absorbing materials>

[0065] (f) A process of laminating a sheet containing short fibers A, B, and C1 with a nonwoven fabric layer β to obtain a laminate.

[0066] (g) The process of melting short fibers C1 with hot air to obtain nonwoven layer α, and melting short fibers C2 to fuse nonwoven layer α and nonwoven layer β together.

[0067] The details of these processes (a) to (g) are described below.

[0068] <Non-woven layer α>

[0069] First, the process of opening short fibers A, B, and C1 (opening process) will be explained. In the opening process, short fibers A, B, and C1 (hereinafter also referred to as each short fiber) are metered in such a way that the content of short fibers A, B, and C1 in the nonwoven layer α reaches the desired content, and then each short fiber is fully opened and blended using air or the like.

[0070] Next, the process of forming short fibers A, B, and C1 into sheet-like material (carding process) in (b) will be described. In the carding process, the short fibers obtained in the opening process after being blended are aligned using a carding roller to obtain a sheet. That is, the sheet is a film-like sheet composed only of fibers, also known as fleece.

[0071] <Non-woven fabric layer β>

[0072] (c) The process of opening short fiber C2 and other short fibers is the same as the process in (a). After the short fiber C2 and other short fibers are metered in the opening process, air or the like is used to fully open and mix each short fiber.

[0073] In addition, regarding the process of (d) making short fiber C2 and other short fibers into sheet form, it is the same as described in (b) by using a carding process to align the short fibers obtained in the opening process after blending with a carding roller to obtain the sheet.

[0074] Next, the process (e) of obtaining nonwoven layer β by interlacing short fiber C2 with other short fibers using needles or water jets (interlacing process) will be described. In the interlacing process, the interlacing of the short fibers is carried out mechanically by needle punching or water jetting (water jet interlacing). By interlacing short fiber C2 with other short fibers in this interlacing process, the tensile elongation at break of nonwoven layer β can be improved, the following ability of nonwoven layer β to the forming die can be improved, and the breakage of nonwoven layer β can be suppressed. Regarding the interlacing process, from a productive point of view, needle punching is preferably used, preferably with a needle density of 30 needles / cm. 2 ~300 strands / cm 2 This can improve the tensile elongation at break of the nonwoven layer β, enhance the following ability of the nonwoven layer β to the forming mold, and suppress the breakage of the nonwoven layer β. This is achieved by setting the needle density to 30 needles / cm². 2 The above can impart interlacing to the nonwoven layer β, thereby improving the tensile elongation at break. On the other hand, by setting the needle density to 300 needles / cm... 2 The following measures can suppress the breakage of short fibers caused by needles and improve the tensile elongation at break. In this respect, the needle density is preferably set to 50 needles / cm². 2 ~200 strands / cm2 Ideally, the number of strands per cm should be 50. 2 ~150 strands / cm 2 .

[0075] <Non-woven fabric laminate for sound-absorbing materials>

[0076] Regarding the process of (f) stacking a sheet containing short fibers A, B, and C1 with a nonwoven fabric layer β to obtain a laminated sheet, it is preferable to use a method of stacking the nonwoven fabric layer β while manufacturing the sheet containing short fibers A, B, and C1.

[0077] Regarding the process of (g) melting short fibers C1 with hot air to obtain nonwoven layer α, and melting short fibers C2 to fuse nonwoven layer α and nonwoven layer β, hot air at 150°C to 220°C flows through the laminate in the thickness direction using a thermal bonding method to melt short fibers C1, thereby obtaining nonwoven layer α, and melting short fibers C2 to fuse nonwoven layer α and nonwoven layer β, thereby efficiently manufacturing the nonwoven fabric for sound-absorbing materials of the present invention.

[0078] Next, the sound-absorbing material will be described. The sound-absorbing material including the non-woven fabric laminate of the present invention is preferably a non-woven fabric laminate having the sound-absorbing material of the present invention, and having an air permeability of 3 cm as the outer skin material. 3 / cm 2 / s~50cm 3 / cm 2 The surface layer of the nonwoven fabric is laminated onto the surface of the nonwoven layer α of the sound-absorbing material. Furthermore, by providing a structure comprising the surface material / nonwoven layer α / nonwoven layer β such that the surface material is the incident side of the sound, the sound absorption performance of the sound-absorbing material becomes excellent. The air permeability of the surface material is set to 3 cm. 3 / cm 2 Sound entering the sound-absorbing material at speeds above a certain threshold can have its absorption performance improved through air friction between the outer layer material and the non-woven fabric used in the sound-absorbing material. Furthermore, by setting the air permeability of the outer layer material to 35cm... 3 / cm 2 The sound absorption performance can be improved by the resonance between the membrane vibration of the outer skin material and the air vibration of the fine porous parts of the nonwoven fabric used for sound absorption, which is preferred. In this respect, the air permeability of the outer skin material is preferably 4 cm⁻¹. 3 / cm 2 / s~40cm 3 / cm 2 / s, preferably 5cm 3 / cm 2 / s~30cm 3 / cm 2 / s. In addition, the air permeability of the skin material was determined according to JIS L1096-1999 8.27.1A method (Frazier type method).

[0079] Furthermore, the preferred structure for sound-absorbing materials is as described above. However, in addition to the nonwoven fabric for the skin with a specific air permeability, if the skin material can achieve the effect of the skin material due to the air friction or resonance, ordinary needle-punched nonwoven fabric, spunlace nonwoven fabric, spunbond nonwoven fabric, meltblown nonwoven fabric, woven fabric, fiberboard, or foam can be laminated on the surface of the nonwoven layer α of the nonwoven fabric for sound-absorbing materials and used as a sound-absorbing material.

[0080] Example

[0081] The evaluation methods and measurement methods used in this embodiment will be described below.

[0082] (1) Determination of the content of each short fiber in the nonwoven fabric laminate constituting the sound-absorbing material

[0083] Nonwoven layer α and nonwoven layer β were separated. For each nonwoven fabric, the positive blending rate (mass ratio of each fiber under standard conditions) was determined based on JIS L 1030-1:2006 "Test method for blending rate of fiber products - Part 1: Fiber identification" and JIS L 1030-2:2005 "Test method for blending rate of fiber products - Part 2: Fiber blending rate". This value was set as the content (mass%) of each fiber constituting the nonwoven fabric laminate for sound-absorbing materials. Thus, the fiber raw materials of nonwoven layer α and nonwoven layer β constituting the nonwoven fabric laminate for sound-absorbing materials, and their content (mass%), were determined.

[0084] (2) Determination of the fineness and mass content of the fibers constituting the nonwoven fabric laminate of the sound-absorbing material

[0085] Regarding the residual nonwoven fabric in nonwoven layer α and nonwoven layer β in the dissolution method of JIS L 1030-2:2005 "Test method for blending rate of fiber products - Part 2: Fiber blending rate" (6. Dissolution method), the cross-section of these residual nonwoven fabrics was observed using a scanning electron microscope (SEM) (Hitachi High-Tech S-3500N model). Thirty observation areas were randomly selected, and cross-sectional photographs at 1000x magnification were taken. Furthermore, the diameter of each individual fiber was measured for all fibers present in the cross-sectional photographs. In addition, at this time, fibers with visible welds and those without visible welds were strictly distinguished in the cross-sectional photographs. The measurement was performed using fibers without visible welds. Furthermore, in the case where the fiber cross-sectional shape is irregular, the cross-sectional area of ​​the fiber was measured based on the cross-sectional photograph, and the cross-sectional area was converted into the diameter of a perfect circle, which was then set as the diameter of each individual fiber. In the obtained data, for fibers where no fusion was observed, the single fiber diameter data were strictly distinguished at intervals of 0.1 μm, and the average single fiber diameter and the number of fibers in each interval were statistically analyzed. Based on the obtained average single fiber diameter of each interval and the specific gravity of each fiber determined in (1), the fineness of the fiber in each interval was calculated using Equation (1).

[0086] Fineness (dtex) = (Average single fiber diameter (μm) / 2) 2 ×3.14× Fiber specific gravity / 100 Formula (1).

[0087] Regarding the nonwoven layer α, for fibers with a fineness of 0.4dtex to 3.8dtex, the content of fibers with a fineness of 0.4dtex to 3.8dtex is calculated by formula (2) based on the fineness of each interval, the number of fibers in each interval, and the proportion of fiber raw materials.

[0088] The mass content (mass%) of fibers with a fineness of 0.4 dtex to 3.8 dtex = ((fineness (dtex) of each interval of fibers with a fineness of 0.4 dtex to 3.8 dtex × number of fibers in each interval)) / (fineness (dtex) of each interval of fibers other than 0.4 dtex to 3.8 dtex × number of fibers in each interval)) × 100 (Equation 2).

[0089] Similarly, the mass content (mass%) of fibers with a fineness of 4.0 dtex to 22.0 dtex was determined. Furthermore, for fibers with visible welds, the fineness and mass content (mass%) were also determined. For the nonwoven layer β, fibers with visible welds were strictly distinguished from those without, and measurements were performed using fibers without visible welds. The fineness and mass content (mass%) of each fiber were then determined.

[0090] In addition, when there are multiple fiber raw materials for nonwoven layer α or nonwoven layer β constituting the nonwoven fabric for sound absorption material, the fineness and content of each fiber raw material are measured using the residual nonwoven fabric in the dissolution method to determine the fineness and content of the fibers constituting the nonwoven fabric for sound absorption material.

[0091] (3) Determination of the melting point of short fibers

[0092] For nonwoven layers α and β, a Shimadzu differential scanning calorimeter (DSC-60) manufactured by Shimadzu Corporation was used. The temperature was measured under a nitrogen flow at a heating rate of 10°C / min. The melting endothermic peak temperature (°C) of the obtained differential scanning calorimetry (DSC) curve was set as the melting point (°C) of the short fibers of each nonwoven layer constituting the nonwoven laminate for sound absorption material. Nonwoven layers α and β contain a variety of short fibers, and each peak was set as the melting point of the short fibers constituting each nonwoven layer. In addition, for nonwoven layers where the resin is amorphous and the melting endothermic peak cannot be confirmed by DSC, a melting point microscope was used to observe the melting start temperature and melting end temperature at a heating rate of 10°C / min, and the melting point was determined by equation (3).

[0093] Melting point (°C) = (melting start temperature (°C) + melting end temperature (°C)) / 2 (Equation 3).

[0094] (4) Determination of the unit area weight of nonwoven layer α, nonwoven layer β, and nonwoven layer laminate for sound absorption material

[0095] The determination was based on JIS L 1913:1998 6.2. Nonwoven layer α and nonwoven layer β were separated from the nonwoven fabric used for sound absorption. Three 200mm × 200mm test pieces were collected from each sample. The mass of the test pieces under standard conditions was measured, and the mass per unit area (i.e., weight per unit area) was calculated using equation (4). The average value was calculated for both nonwoven layer α and nonwoven layer β.

[0096] ms = m / S (Equation 4)

[0097] ms: Mass per unit area (g / m²) 2 )

[0098] m: Average mass (g) of the test piece with nonwoven layer α or nonwoven layer β.

[0099] S: Area of ​​the test piece with nonwoven layer α or nonwoven layer β (m²) 2 )

[0100] Furthermore, the unit area weight of the nonwoven fabric used for sound absorption material is set as the total unit area weight of the nonwoven fabric layer α and the nonwoven fabric layer β.

[0101] (5) Determination of the thickness of nonwoven layer α, nonwoven layer β, and nonwoven fabric used for sound absorption.

[0102] Nonwoven layer α and nonwoven layer β were separated from a sample of nonwoven fabric for sound absorption material, and five 200mm × 200mm test pieces were collected. The thickness of nonwoven layer α and nonwoven layer β was measured by aligning a ruler with the cross-section of the test piece. Measurements were performed on each of the five test pieces, and the average value was calculated. Furthermore, the thickness of the nonwoven fabric for sound absorption material was measured without separating nonwoven layer α and nonwoven layer β.

[0103] (6) Determination of tensile elongation at break of nonwoven layer β

[0104] The measurements were performed based on JIS L 1913:1998 6.3.1. Five test pieces, each 50 mm wide and 200 mm long, were collected from a nonwoven fabric used for sound absorption, separated from the nonwoven fabric layer β. Additionally, five more test pieces, each 50 mm wide and 200 mm long, were collected in a direction perpendicular to the aforementioned direction. For the obtained test pieces (a total of 10 pieces), a constant-speed elongation tensile testing machine was used, with a grip interval of 100 mm and a tensile speed of 200 mm / min, until the test piece broke. The tensile elongation at break (%) was measured. The average value was calculated for all 10 test pieces. As an evaluation, a higher tensile elongation at break indicates better formability.

[0105] (7) Determination of the static friction coefficient of nonwoven fabric used for sound-absorbing materials

[0106] The measurement was performed according to JIS P8147:1994 3.2 tilting method. Five test pieces, each 250 mm wide and 100 mm long, were collected from the nonwoven fabric used for sound absorption in any direction. Additionally, five more test pieces, each 250 mm wide and 100 mm long, were collected in a direction perpendicular to the aforementioned direction. The resulting 10 test pieces were mounted on the tilting plate of the sliding tilting angle measuring device with the long side of the test piece parallel to the long side of the tilting plate and the nonwoven fabric layer β forming the upper surface. A metal weight (60 mm wide, 100 mm long, 1000 g in mass) was then placed on the test piece with the long side of the test piece parallel to the long side of the weight.

[0107] In the measurement, the inclined plate was tilted with an inclination angle of less than 3° / second, and the inclination angle when the weight fell was read. The tangent (tanθ) of the inclination angle was taken as the static friction coefficient. Measurements were performed on 10 test pieces, and the average value was calculated. As an evaluation, the smaller the static friction coefficient, the better the smoothness.

[0108] (8) Evaluation of the thickness recovery of nonwoven fabrics used for sound absorption materials during molding.

[0109] Five test pieces, each 500 mm wide, 500 mm long, and 30 mm thick (25 mm thick in Comparative Example 12), were collected from the nonwoven fabric for sound absorption material in any direction. The ends of the test pieces were fixed using a holding metal piece. The upper and lower surfaces of the test pieces were heated using a far-infrared heater heated to 220°C until the internal temperature of the nonwoven fabric reached 150°C. The heated test pieces were then rapidly moved and pressed between metal plates (400 mm × 400 mm) at 20°C under a pressure of 800 kPa for 60 seconds. The pressed test pieces were cut into 300 mm × 300 mm pieces. The thickness (mm) immediately after pressing was measured using a metal ruler aligned with the cross-section of the test piece. The average value obtained by dividing the thickness (mm) of the five test pieces by the thickness before pressing was calculated. A larger value indicates better thickness recovery during forming.

[0110] (9) Evaluation of fiber shedding during cutting of nonwoven fabric for sound-absorbing materials

[0111] Using cutting scissors, the compressed test piece (300mm × 300mm) prepared in step (8) is cut in the center to a length of 300mm. The total amount of shed fibers is collected, and its mass (mg) is measured using an electronic balance. The result is converted using the following formula (5) with a cut length of 1m, and set as the fiber shedding amount at the time of cutting (mg / m). Five test pieces are measured, the average value is calculated, and then the pieces are cut. The smaller the value of the fiber shedding amount at the time of cutting, the less fiber is shed, and the better the result.

[0112] The amount of fiber detached during cutting (mg / m) = mass of detached fiber (mg) / cutting length (m) Equation (5).

[0113] (10) Determination of the vertical incident sound absorption rate of sound-absorbing materials

[0114] The sound absorption was measured according to the vertical incident sound absorption method (in-tube method) of JIS A 1405 (1998). Three circular test pieces with a diameter of 92 mm were collected from the pressed test pieces (300 mm × 300 mm) prepared in (8). Then, a nonwoven fabric containing 40% by mass of polyethylene terephthalate (PET) short fibers of 0.9 dtex and 60% by mass of polyethylene terephthalate (PET) short fibers of 2.2 dtex (250 g / m²) was used for the skin. 2 Thickness 1.4mm, Fraser breathability 24cm 3 / cm 2 ( / s), collect 3 circular test pieces 2 with a diameter of 92mm. Then, stack the test pieces 2 on the surface of the nonwoven fabric layer α of the test pieces 1.

[0115] As the experimental setup, an automatic vertical incident absorption rate measuring instrument (model 10041A) manufactured by Electronic Instruments Co., Ltd. was used. For the test piece, the test piece 2 was mounted on one end of the measuring impedance tube with the sound incident side as the test piece 2, and the vertical incident absorption rate was measured. The absorption rate for each frequency was calculated by multiplying the absorption coefficient obtained in the measurement by 100. Then, the average absorption rate obtained at 1000 Hz was set as the low-frequency absorption rate (%), and the average absorption rate obtained at 2000 Hz was set as the high-frequency absorption rate (%).

[0116] <Example 1>

[0117] Example 1 uses the following nonwoven fabric laminate.

[0118] (Non-woven layer α)

[0119] Short fiber A consists of 35% by mass of polyethylene terephthalate (PET) staple fibers with a fineness of 0.6 dtex and a melting point of 255°C, 60% by mass of polyethylene terephthalate (PET) staple fibers with a fineness of 6.6 dtex and a melting point of 255°C, and 5% by mass of core-sheath short fibers with a fineness of 2.2 dtex and a core containing polyethylene terephthalate (PET) with a melting point of 255°C and a sheath containing crystalline copolyester with a melting point of 160°C (core-sheath ratio 1:1). After the short fibers are fed into the opening process, they are fed into the carding process to obtain the sheet.

[0120] (non-woven layer β)

[0121] Short fibers C2 consist of 70% by mass of polyethylene terephthalate (PET) staple fibers with a fineness of 6.6 dtex and a melting point of 255°C, and 30% by mass of core-sheath short fibers with a fineness of 4.4 dtex and a core containing PET with a melting point of 255°C and a sheath containing amorphous copolyester with a melting point of 110°C (core-sheath ratio 1:1). These short fibers are fed to the opening process, then to the carding process, and finally to the needle-punching process (needle density 100 fibers / cm²). 2 ), to obtain needle-punched nonwoven fabric.

[0122] (Sound-absorbing material made of non-woven fabric laminate)

[0123] The sheet of nonwoven fabric layer β is laminated with the needle-punched nonwoven fabric of nonwoven fabric layer β and then subjected to a thermal bonding process (hot air temperature 180°C). The sheet contains 95% by mass of short fiber A and short fiber B, the mass ratio of short fiber A to short fiber B is 0.58, and the unit area weight is 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate with a thickness of 30 mm is obtained by using a nonwoven fabric layer β with a thickness of 5 mm.

[0124] In the nonwoven fabric laminate for sound-absorbing material of Example 1, the nonwoven layer β exhibits high tensile elongation at break, excellent conformability, low static friction coefficient, and excellent smoothness. Furthermore, it has a large thickness after pressing, excellent thickness recovery during forming, and minimal fiber shedding during cutting. Consequently, the laminated nonwoven fabric for sound-absorbing material exhibits high low-frequency sound absorption and high high-frequency sound absorption.

[0125] <Example 2>

[0126] The short fiber A in the nonwoven fabric layer α was replaced with polyethylene terephthalate (PET) short fibers with a fineness of 2.2 dtex and a melting point of 255°C. Otherwise, the fabric was treated using the same procedures and conditions as in Example 1, resulting in a short fiber content of 95% by mass for short fibers A and B, a short fiber A to short fiber B content ratio of 0.58, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric for sound absorption material was obtained by forming a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material of Example 2 are shown in Table 1.

[0127] <Example 3>

[0128] The short fiber A in the nonwoven fabric layer α was replaced with polyethylene terephthalate (PET) short fibers with a fineness of 3.3 dtex and a melting point of 255°C. Otherwise, the fabric was treated using the same procedures and conditions as in Example 1, resulting in a short fiber content of 95% by mass for short fiber A and short fiber B, a short fiber A to short fiber B content ratio of 0.58, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by using a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 1.

[0129] <Example 4>

[0130] The short fiber B in the nonwoven layer α was replaced with polyethylene terephthalate (PET) short fibers with a fineness of 14.4 dtex and a melting point of 255°C. Otherwise, the fabric was treated using the same procedures and conditions as in Example 1, resulting in a short fiber content of 95% by mass of short fiber A and short fiber B, a short fiber A to short fiber B content ratio of 0.58, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by using a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 1.

[0131] <Example 5>

[0132] Short fiber A from Example 1 was used as short fiber A in nonwoven layer α, short fiber B from Example 1 was used as short fiber B in nonwoven layer α, and short fiber C1 from Example 1 was used as short fiber C1 in nonwoven layer α. The content of these fibers was changed to 36% by mass, 62% by mass, and 2% by mass, respectively. Otherwise, the same process and conditions as in Example 1 were used for processing, resulting in a short fiber A to short fiber B content of 98% by mass, a short fiber A to short fiber B content ratio of 0.58, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by using a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 1.

[0133] <Example 6>

[0134] Short fiber A from Example 1 was used as short fiber A in nonwoven layer α, short fiber B from Example 1 was used as short fiber B in nonwoven layer α, and short fiber C1 from Example 1 was used as short fiber C1 in nonwoven layer α. The content of these fibers was changed to 34% by mass, 58% by mass, and 8% by mass, respectively. Otherwise, the same process and conditions as in Example 1 were used for processing, resulting in a short fiber A to short fiber B content of 92% by mass, a short fiber A to short fiber B content ratio of 0.59, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by using a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 1.

[0135] <Example 7>

[0136] Short fiber A from Example 1 was used as short fiber A in nonwoven layer α, short fiber B from Example 1 was used as short fiber B in nonwoven layer α, and short fiber C1 from Example 1 was used as short fiber C1 in nonwoven layer α. The content of these fibers was changed to 32% by mass, 56% by mass, and 12% by mass, respectively. Otherwise, the process was performed using the same procedures and conditions as in Example 1, resulting in a short fiber A to short fiber B content of 88% by mass, a short fiber A to short fiber B content ratio of 0.57, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by using a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 2.

[0137] <Example 8>

[0138] Short fiber A from Example 1 was used as short fiber A in nonwoven layer α, short fiber B from Example 1 was used as short fiber B in nonwoven layer α, and short fiber C1 from Example 1 was used as short fiber C1 in nonwoven layer α. The content of these fibers was changed to 15% by mass, 80% by mass, and 5% by mass, respectively. Otherwise, the fabric was processed using the same procedures and conditions as in Example 1, resulting in a short fiber A to short fiber B content of 95% by mass, a short fiber A to short fiber B content ratio of 0.19, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by using a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 2.

[0139] <Example 9>

[0140] Short fiber A from Example 1 was used as the short fiber A of nonwoven layer α, short fiber B from Example 1 was used as the short fiber B of nonwoven layer α, and short fiber C1 from Example 1 was used as the short fiber C1 of nonwoven layer α. The content of these fibers was changed to 50% by mass, 45% by mass, and 5% by mass, respectively. Otherwise, the same process and conditions as in Example 1 were used for processing, resulting in a short fiber A to short fiber B content of 95% by mass, a short fiber A to short fiber B content ratio of 1.11, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by using a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 2.

[0141] <Example 10>

[0142] Short fiber A from Example 1 was used as short fiber A in nonwoven layer α, short fiber B from Example 1 was used as short fiber B in nonwoven layer α, and short fiber C1 from Example 1 was used as short fiber C1 in nonwoven layer α. The content of these fibers was changed to 60% by mass, 35% by mass, and 5% by mass, respectively. Otherwise, the same process and conditions as in Example 1 were used for processing, resulting in a short fiber A to short fiber B content of 95% by mass, a short fiber A to short fiber B content ratio of 1.71, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2A nonwoven fabric laminate for sound absorption material was obtained by using a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 2.

[0143] <Example 11>

[0144] The short fibers C1 of the nonwoven layer α were changed to core-sheath short fibers with a fineness of 2.2 dtex and a core containing polyethylene terephthalate (PET) with a melting point of 255°C and a sheath containing crystalline copolyester with a melting point of 140°C (core-sheath ratio 1:1). Otherwise, the fabric was processed using the same procedures and conditions as in Example 1, with a short fiber content of 95% by mass of short fiber A and short fiber B, a short fiber A to short fiber B content ratio of 0.58, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by using a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 2.

[0145] <Example 12>

[0146] The short fibers C1 of the nonwoven layer α were changed to core-sheath short fibers with a fineness of 2.2 dtex and a core containing polyethylene terephthalate (PET) with a melting point of 255°C and a sheath containing crystalline copolyester with a melting point of 150°C (core-sheath ratio 1:1). Otherwise, the fabric was processed using the same procedures and conditions as in Example 1, with a short fiber content of 95% by mass of short fiber A and short fiber B, a short fiber A to short fiber B content ratio of 0.58, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by using a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 2.

[0147] <Example 13>

[0148] The short fibers C1 of the nonwoven layer α were changed to core-sheath short fibers with a fineness of 2.2 dtex and a core containing polyethylene terephthalate (PET) with a melting point of 255°C and a sheath containing crystalline copolyester with a melting point of 175°C (core-sheath ratio 1:1). Otherwise, the fabric was processed using the same procedures and conditions as in Example 1, with a short fiber content of 95% by mass of short fiber A and short fiber B, a short fiber A to short fiber B content ratio of 0.58, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2A nonwoven fabric laminate for sound absorption material was obtained by using a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 3.

[0149] <Example 14>

[0150] The short fibers C1 of the nonwoven layer α were changed to core-sheath short fibers with a fineness of 2.2 dtex and a core containing polyethylene terephthalate (PET) with a melting point of 255°C and a sheath containing amorphous copolyester with a melting point of 160°C (core-sheath ratio 1:1). Otherwise, the fabric was processed using the same procedures and conditions as in Example 1, with a short fiber content of 95% by mass of short fiber A and short fiber B, a short fiber A to short fiber B content ratio of 0.58, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by using a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 3.

[0151] <Example 15>

[0152] Polyethylene terephthalate (PET) staple fibers with a fineness of 6.6 dtex and a melting point of 255°C were used as the staple fibers for nonwoven layer β. Staple fiber C2 from Example 1 was used as the staple fiber C2 for nonwoven layer β, with the content of C2 and C2 changed to 60% by mass and 40% by mass, respectively. Otherwise, the fabric was processed using the same procedures and conditions as in Example 1, resulting in a staple fiber content of 95% by mass for staple fiber A and staple fiber B, a staple fiber A to staple fiber B content ratio of 0.58, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by using a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 3.

[0153] <Example 16>

[0154] Polyethylene terephthalate (PET) staple fibers with a fineness of 6.6 dtex and a melting point of 255°C were used as the staple fibers for nonwoven layer β. Staple fiber C2 from Example 1 was used as the staple fiber C2 for nonwoven layer β, with the content of C2 and C2 changed to 50% by mass and 50% by mass, respectively. Otherwise, the processing was carried out using the same procedures and conditions as in Example 1, resulting in a staple fiber content of 95% by mass for staple fiber A and staple fiber B, a staple fiber A to staple fiber B content ratio of 0.58, and a unit area weight of 300 g / m². 2A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by using a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 3.

[0155] <Example 17>

[0156] The unit area weight of the nonwoven layer α was changed to 250 g / m². 2 In addition, the same process and conditions as in Example 1 were used for processing, with the content of short fiber A and short fiber B being 95% by mass, the content ratio of short fiber A to short fiber B being 0.58, and the unit area weight being 250 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by using a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 3.

[0157] <Example 18>

[0158] The unit area weight of the nonwoven layer α is changed to 200 g / m². 2 In addition, the same process and conditions as in Example 1 were used for processing, with the content of short fiber A and short fiber B being 95% by mass, the content ratio of short fiber A to short fiber B being 0.58, and the unit area weight being 200 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by using a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 3.

[0159]

[0160]

[0161]

[0162] In the nonwoven fabrics for sound-absorbing materials described in Examples 1 to 18, the nonwoven layer β exhibits high tensile elongation at break, excellent conformability, low static friction coefficient, and excellent smoothness. Furthermore, it has a relatively large thickness after pressing, excellent thickness recovery during forming, and minimal fiber shedding during cutting. Consequently, the laminated nonwoven fabric for sound-absorbing materials exhibits high low-frequency sound absorption and high-frequency sound absorption.

[0163] Compared to the nonwoven fabric laminate for sound-absorbing material in Comparative Example 10, the nonwoven fabric laminate for sound-absorbing material in the embodiments exhibits higher tensile elongation at break and better conformability due to the effect of short fiber C2 content, lower static friction coefficient, and better smoothness. Furthermore, regarding the large thickness after pressing and the thickness recovery during forming, the nonwoven fabric laminate for sound-absorbing material in the embodiments is superior to that in Comparative Example 3 due to the effect of short fiber B, superior to that in Comparative Example 4 due to the effect of short fiber C1, superior to that in Comparative Example 7 due to the effect of the mass ratio of short fiber A to short fiber B, and superior to that in Comparative Example 8 due to the effect of the melting point of the sheath of short fiber C1.

[0164] Regarding the amount of fiber loss during cutting, in comparison with Comparative Example 5, the amount of fiber loss was less and better due to the effect of the content of short fiber C1. In comparison with Comparative Example 9, the amount of fiber loss was less and better due to the effect of the melting point of the sheath of short fiber C1.

[0165] Furthermore, in comparisons with Comparative Examples 1, 2, 3, 6, and 7, the effects of the fineness, amount, or ratio of short fibers A and B resulted in a nonwoven fabric laminate for sound-absorbing materials with high low-frequency and high-frequency sound absorption rates. In comparisons with Comparative Examples 4 and 8, the effects of the content of short fiber C1 or the melting point of the sheath resulted in a nonwoven fabric laminate for sound-absorbing materials with high low-frequency and high-frequency sound absorption rates. Comparative examples are shown below.

[0166] <Comparative Example 1>

[0167] The short fiber A in the nonwoven fabric layer α was replaced with polyethylene terephthalate (PET) short fibers with a fineness of 0.3 dtex and a melting point of 255°C. Otherwise, the fabric was treated using the same procedures and conditions as in Example 1, resulting in a short fiber content of 95% by mass of short fiber A and short fiber B, a short fiber A to short fiber B content ratio of 0.58, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by using a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 4.

[0168] In Comparative Example 1, the nonwoven fabric for sound absorption material exhibits high tensile elongation at break, excellent conformability, low static friction coefficient, and excellent smoothness in nonwoven fabric layer β. Furthermore, it has a large thickness after pressing, excellent thickness recovery during forming, and minimal fiber shedding during cutting. However, the laminated nonwoven fabric for sound absorption material exhibits low low-frequency sound absorption and low high-frequency sound absorption.

[0169] <Comparative Example 2>

[0170] 95% by mass of polyethylene terephthalate (PET) staple fibers with a fineness of 4.4 dtex and a melting point of 255°C were used as staple fiber B for nonwoven layer α, and 5% by mass of staple fiber C1 from Example 1 was used as staple fiber C1 for nonwoven layer α. Staple fiber A was not used. Otherwise, the fabric was processed using the same procedures and conditions as in Example 1, resulting in a composition of 95% by mass of staple fiber A and staple fiber B with a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by forming a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 4. In Comparative Example 2, the nonwoven fabric for sound absorption material laminate has low low-frequency sound absorption rate and low high-frequency sound absorption rate.

[0171] <Comparative Example 3>

[0172] 95% by mass of polyethylene terephthalate (PET) staple fibers with a fineness of 3.6 dtex and a melting point of 255°C were used as staple fiber A for nonwoven layer α, and 5% by mass of staple fiber C1 from Example 1 was used as staple fiber C1 for nonwoven layer α. Staple fiber B was not used. Otherwise, the fabric was processed using the same procedures and conditions as in Example 1, resulting in a fabric with a content of 95% by mass of staple fiber A and staple fiber B and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by forming a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 4. In Comparative Example 3, the nonwoven fabric for sound absorption material has a small thickness after pressing, poor thickness recovery during forming, and low low-frequency and low high-frequency sound absorption rates.

[0173] <Comparative Example 4>

[0174] Short fiber A from Example 1 was used as short fiber A in nonwoven layer α, short fiber B from Example 1 was used as short fiber B in nonwoven layer α, and short fiber C1 from Example 1 was used as short fiber C1 in nonwoven layer α. The content of these fibers was changed to 30% by mass, 55% by mass, and 15% by mass, respectively. Otherwise, the process was performed using the same procedures and conditions as in Example 1, resulting in a short fiber A to short fiber B content of 85% by mass, a short fiber A to short fiber B content ratio of 0.55, and a unit area weight of 300 g / m². 2A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by forming a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 4. In Comparative Example 4, the nonwoven fabric for sound absorption material has a small thickness after pressing, poor thickness recovery during forming, and low low-frequency and low high-frequency sound absorption rates.

[0175] <Comparative Example 5>

[0176] Short fiber A from Example 1 was used as short fiber A in nonwoven layer α, short fiber B from Example 1 was used as short fiber B in nonwoven layer α, and short fiber C1 from Example 1 was used as short fiber C1 in nonwoven layer α. The content of these fibers was changed to 37% by mass, 62% by mass, and 1% by mass, respectively. Otherwise, the same process and conditions as in Example 1 were used for processing, resulting in a short fiber A to short fiber B content of 99% by mass, a short fiber A to short fiber B content ratio of 0.60, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by forming a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 4. In Comparative Example 5, the nonwoven fabric for sound absorption material had a large amount of fiber shedding during cutting, which was poor.

[0177] <Comparative Example 6>

[0178] Short fiber A from Example 1 was used as the short fiber A of nonwoven layer α, short fiber B from Example 1 was used as the short fiber B of nonwoven layer α, and short fiber C1 from Example 1 was used as the short fiber C1 of nonwoven layer α. The content of these fibers was changed to 4% by mass, 91% by mass, and 5% by mass, respectively. Otherwise, the same process and conditions as in Example 1 were used for processing, resulting in a short fiber A to short fiber B content of 95% by mass, a short fiber A to short fiber B content ratio of 0.04, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by forming a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 4. In Comparative Example 6, the nonwoven fabric for sound absorption material laminate has low low-frequency sound absorption rate and low high-frequency sound absorption rate.

[0179] <Comparative Example 7>

[0180] Short fiber A from Example 1 was used as short fiber A in nonwoven layer α, short fiber B from Example 1 was used as short fiber B in nonwoven layer α, and short fiber C1 from Example 1 was used as short fiber C1 in nonwoven layer α. The content of these fibers was changed to 76% by mass, 19% by mass, and 5% by mass, respectively. Otherwise, the same process and conditions as in Example 1 were used for processing, resulting in a short fiber A to short fiber B content of 95% by mass, a short fiber A to short fiber B content ratio of 4.00, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by forming a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 5. In Comparative Example 7, the nonwoven fabric for sound absorption material has a small thickness after pressing, poor thickness recovery during forming, and low low-frequency and low high-frequency sound absorption rates.

[0181] <Comparative Example 8>

[0182] The short fibers C1 of the nonwoven layer α were changed to core-sheath short fibers with a fineness of 2.2 dtex and a core containing polyethylene terephthalate (PET) with a melting point of 255°C and a sheath containing crystalline copolyester with a melting point of 130°C (core-sheath ratio 1:1). Otherwise, the fabric was processed using the same procedures and conditions as in Example 1, with a short fiber content of 95% by mass of short fiber A and short fiber B, a short fiber A to short fiber B content ratio of 0.58, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by forming a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 5. In Comparative Example 8, the nonwoven fabric for sound absorption material has a small thickness after pressing, poor thickness recovery during forming, low low-frequency sound absorption rate, and low high-frequency sound absorption rate.

[0183] <Comparative Example 9>

[0184] The short fibers C1 of the nonwoven layer α were changed to core-sheath short fibers with a fineness of 2.2 dtex and a core containing polyethylene terephthalate (PET) with a melting point of 255°C and a sheath containing crystalline copolyester with a melting point of 195°C (core-sheath ratio 1:1). Otherwise, the fabric was processed using the same procedures and conditions as in Example 1, with a short fiber content of 95% by mass of short fiber A and short fiber B, a short fiber A to short fiber B content ratio of 0.58, and a unit area weight of 300 g / m². 2A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by forming a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 5. In Comparative Example 9, the nonwoven fabric for sound absorption material had a large amount of fiber shedding during cutting, which was poor.

[0185] <Comparative Example 10>

[0186] Polyethylene terephthalate (PET) staple fibers with a fineness of 6.6 dtex and a melting point of 255°C were used as the staple fibers for nonwoven layer β. Staple fiber C2 from Example 1 was used as the staple fiber C2 for nonwoven layer β, with the content of C2 and C2 changed to 82% by mass and 18% by mass, respectively. Otherwise, the process was performed using the same procedures and conditions as in Example 1, resulting in a staple fiber content of 95% by mass for staple fiber A and staple fiber B, a staple fiber A to staple fiber B content ratio of 0.58, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by forming a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 5. In Comparative Example 10, the nonwoven fabric for sound absorption material has a high static friction coefficient and poor smoothness.

[0187] <Comparative Example 11>

[0188] Polyethylene terephthalate (PET) staple fibers with a fineness of 6.6 dtex and a melting point of 255°C were used as the staple fibers for nonwoven layer β. Staple fiber C2 from Example 1 was used as the staple fiber C2 for nonwoven layer β, with the content of C2 changed to 35% by mass and C2 to 65% by mass, respectively. Otherwise, the process and conditions were the same as in Example 1, resulting in a staple fiber content of 95% by mass for both staple fiber A and staple fiber B, a staple fiber A to staple fiber B content ratio of 0.58, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric laminate for sound absorption material was obtained by forming a nonwoven fabric layer β with a thickness of 5 mm. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 5. In the nonwoven fabric for sound absorption material of Comparative Example 11, the nonwoven fabric layer β has low tensile elongation at break and poor followability.

[0189] <Comparative Example 12>

[0190] A nonwoven fabric for sound absorption material, containing only a nonwoven layer α and not a nonwoven layer β, was produced. Otherwise, it was processed using the same procedures and conditions as in Example 1 to obtain a short fiber A to short fiber B content of 95% by mass, a short fiber A to short fiber B content ratio of 0.58, and a unit area weight of 300 g / m². 2 The nonwoven fabric used for sound absorption material has a nonwoven layer α with a thickness of 25 mm. The structure and evaluation results of the nonwoven fabric used for sound absorption material are shown in Table 5.

[0191] The nonwoven fabric used for sound-absorbing material in Comparative Example 12, due to the absence of a nonwoven layer β, has a high static friction coefficient and poor smoothness. During the pressing process, friction with the metal pressure plate causes some of the nonwoven fabric to abrade or tear. It has a large thickness after pressing, excellent thickness recovery during forming, and minimal and good fiber shedding during cutting. However, the layered nonwoven fabric used for sound-absorbing material exhibits low low-frequency and low high-frequency sound absorption rates.

[0192] <Comparative Example 13>

[0193] The short fiber C2 without the nonwoven layer β was replaced with 100% by mass of polyethylene terephthalate (PET) short fibers with a fineness of 6.6 dtex and a melting point of 255°C. Otherwise, it was processed using the same procedures and conditions as in Example 1, resulting in a short fiber content of 95% by mass for short fibers A and B, a short fiber A to short fiber B content ratio of 0.58, and a unit area weight of 300 g / m². 2 A nonwoven fabric layer α with a thickness of 25mm and a unit area weight of 60g / m² 2 A nonwoven fabric for sound absorption material was obtained by forming a nonwoven fabric layer β with a thickness of 5 mm. The nonwoven fabric layers α and β were not partially fused together. The structure and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 5.

[0194] In Comparative Example 13, the nonwoven fabric for sound absorption material did not use short fiber C2. Therefore, the nonwoven fabric layer α and the nonwoven fabric layer β were not integrated during the thermal bonding process, making it impossible to obtain a nonwoven fabric laminate for sound absorption material. During the pressing process, the nonwoven fabric layer α and the nonwoven fabric layer β were not integrated and separated, resulting in wrinkles on the surface of the nonwoven fabric. The quality was very poor, so the vertical incident sound absorption rate could not be measured.

[0195]

[0196]

[0197] Industrial availability

[0198] The nonwoven fabric for sound-absorbing materials of the present invention is particularly suitable for use as a sound-absorbing material in automobiles and the like due to its excellent thickness recovery and conformability during forming and its excellent sound absorption performance.

Claims

1. A nonwoven fabric laminate for sound-absorbing materials, comprising a nonwoven fabric layer α and a nonwoven fabric layer β laminated together, wherein, The nonwoven layer α contains short fibers A with a fineness of 0.4 dtex to 3.8 dtex, short fibers B with a fineness of 4.0 dtex to 22.0 dtex, and short fibers C1 containing a resin with a melting point of 145°C to 190°C in the outer surface layer. The combined mass of short fibers A and B relative to the total mass of the nonwoven fabric layer α is 86% to 98% by mass, and the mass of short fibers C1 relative to the total mass of the nonwoven fabric layer α is 2% to 14% by mass. The mass ratio of short fibers A to short fibers B is 0.05 to 3.

80. The nonwoven layer β contains short fibers C2, which have a resin with a melting point of 70°C to 110°C in the outer surface layer. The content of the short fibers C2 relative to the total mass of the nonwoven layer β is 20% to 60% by mass. The weight per unit area of ​​the nonwoven layer β is lower than that of the nonwoven layer α, and The nonwoven fabric layer α and the nonwoven fabric layer β are partially fused together.

2. The nonwoven laminate for sound-absorbing material according to claim 1, wherein the short fiber C1 is a core-sheath type composite short fiber, and the resin constituting the sheath is a thermoplastic resin with a melting point of 145°C to 190°C.

3. The nonwoven laminate for sound-absorbing materials according to claim 1 or 2, wherein the fineness of the short fibers C1 is 1.0 dtex to 5.0 dtex.

4. The nonwoven laminate for sound-absorbing materials according to claim 1 or 2, wherein the thermoplastic resin with a melting point of 145°C to 190°C is a crystalline resin.

5. The nonwoven laminate for sound-absorbing materials according to claim 1 or 2, wherein the short fiber C2 is a core-sheath type composite short fiber, and the resin constituting the sheath is a thermoplastic resin with a melting point of 70°C to 110°C.

6. The nonwoven laminate for sound-absorbing materials according to claim 1 or 2, wherein the thermoplastic resin with a melting point of 70°C to 110°C is a non-crystalline resin.

7. The nonwoven fabric laminate for sound-absorbing material according to claim 1 or 2, wherein the unit area weight of the nonwoven fabric layer α is 100 g / m². 2 Above and 700 g / m 2 Hereinafter, the thickness of the nonwoven fabric layer α is 7 mm or more and 40 mm or less.

8. The nonwoven fabric laminate for sound-absorbing material according to claim 1 or 2, wherein the unit area weight of the nonwoven fabric layer β is 30 g / m². 2 Above and 120 g / m 2 the following.

9. The nonwoven fabric laminate for sound-absorbing material according to claim 1 or 2, wherein the tensile elongation at break of the nonwoven fabric layer β is 50% or more, and the static friction coefficient is 0.5 or less.

10. The nonwoven laminate for sound-absorbing materials according to claim 1 or 2, wherein the short fiber A, the short fiber B, the short fiber C1 and the short fiber C2 are all polyester short fibers.

11. A sound-absorbing material, wherein the sound-absorbing material as described in any one of claims 1 to 10 is used as a non-woven fabric laminate as a substrate, and further comprises an air permeability of 3 cm. 3 / cm 2 / s~50 cm 3 / cm 2 / s of the skin nonwoven fabric layer γ, which is laminated on the surface of the nonwoven fabric layer α side of the sound-absorbing material nonwoven fabric laminate.

Images