Nonwoven fabric laminate for sound absorbing material and sound absorbing material

Abstract

The present invention addresses the problem of providing a non-woven fabric for a sound-absorbing material, and a sound-absorbing material, that have exceptional thickness recovery properties and following properties during molding and also have exceptional sound-absorbing performance. In order to solve this problem, the present invention provides a non-woven fabric layered body for a sound-absorbing material in which a non-woven fabric layer α and a non-woven fabric layer β are layered, wherein: the non-woven fabric layer α contains staple fibers A having a fineness of 0.4-3.8 dtex, staple fibers B having a fineness of 4.0-22.0 dtex, and staple fibers C1 in which a resin having a melting point of 135-190°C is included in an outer layer, the total of the staple fiber A content and staple fiber B content being 86-98 mass% relative to the entire mass of the non-woven fabric layer α, the staple fiber C1 content being 2-14 mass% relative to the entire mass of the non-woven fabric layer α, and the content ratio (staple fiber A content / staple fiber B content) of the staple fibers A and the staple fibers B being 0.05-3.80; the non-woven fabric layer β contains staple fibers C2 in which a resin having a melting point of 70-190°C is included in an outer layer; and the staple fiber C2 content is 20-60 mass% relative to the entire mass of the non-woven fabric layer β, the non-woven fabric layer α and the non-woven fabric layer β being partially fused.

Description

[Technical field]

[0001] The present invention relates to a nonwoven fabric for sound absorbing material and a sound absorbing material. [Background technology]

[0002] In recent years, quietness has become more important than ever as one of the commercial values ​​of automobiles and electrical appliances. In general, it is considered effective to increase the mass and thickness of the sound-absorbing material used as a noise countermeasure, but there is a demand for lighter and more compact sound-absorbing materials in order to maintain a large space inside the automobile or passenger compartment and to reduce fuel consumption in automobiles. In addition, in automobiles, technology is often used to mold sound-absorbing materials into the shape of parts by molding, so that the sound-absorbing material can be fitted to the complex shapes of the automobile body and installed compactly.

[0003] Patent Document 1 proposes a molded sound-absorbing material in which a composite material made of a base material made of nonwoven fabric or a resin foam and a skin material is clamped in a molding die.

[0004] Patent Document 2 proposes a sound-absorbing material made of a fiber assembly containing staple fibers with a high softening point and a fineness of 1.5 to 20 denier, staple fibers with a medium softening point and a fineness of 1.5 to 15 denier, and staple fibers with a low softening point and a fineness of 1.5 to 15 denier. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2012-24955 A [Patent Document 2] Japanese Patent Application Publication No. 10-245755 Summary of the Invention [Problem to be solved by the invention]

[0006] According to the findings of the present inventors, the molded sound-absorbing material disclosed in Patent Document 1 is easily shaped by molding because it is made by heating and molding a nonwoven fabric containing low-melting-point yarn. However, when low-melting-point yarn with a low melting point is used or the content by mass of low-melting-point yarn is large, the adhesive action of the low-melting-point yarn when it melts and resolidifies results in a thin thickness after molding, which results in a problem of inferior sound-absorbing performance.

[0007] On the other hand, the sound-absorbing material disclosed in Patent Document 2 contains high-softening point synthetic fiber staples having a relatively high softening point, and therefore tends to have relatively excellent heat resistance assuming a temperature rise inside a vehicle cabin. However, when the content of medium-softening point synthetic fiber staples is high, the thickness after molding becomes thin due to the melting and adhesive action, resulting in a problem of inferior sound-absorbing performance.

[0008] Furthermore, there is a problem that the surface of the sound-absorbing material is easily scraped or torn due to friction between the sound-absorbing material such as the nonwoven fabric and the mold during molding. In view of the above circumstances, the present invention has an object to provide a nonwoven fabric laminate for sound-absorbing material that has good sinking resilience during molding, excellent thickness recovery, excellent moldability to conform to the complex shapes of automobile bodies, and excellent sound-absorbing performance. [Means for solving the problem]

[0009] (1) A nonwoven fabric laminate for sound absorbing materials, in which a nonwoven fabric layer α and a nonwoven fabric layer β are laminated, the nonwoven fabric layer α contains short fibers A having a fineness of 0.4 to 3.8 dtex, short fibers B having a fineness of 4.0 to 22.0 dtex, and short fibers C1 having a resin having a melting point of 135 to 190°C in an outer surface layer, the total content of the short fibers A and B relative to the total mass of the nonwoven fabric layer α is 86 to 98 mass%, and the content of the short fibers C1 relative to the total mass of the nonwoven fabric layer α is 86 to 98 mass%. The mass content is 2 to 14 mass%, 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 fabric layer β contains short fiber C2 having a resin with a melting point of 70 to 190°C in its outer surface layer, the mass content of the short fiber C2 relative to the total mass of the nonwoven fabric layer β is 20 to 60 mass%, and the nonwoven fabric layer α and the nonwoven fabric layer β are partially fused to each other to provide a nonwoven fabric laminate for sound-absorbing materials.

[0010] (2) The sound-absorbing nonwoven fabric laminate according to (1), wherein the staple fibers C1 are core-sheath type composite staple fibers, and the resin constituting the sheath is a thermoplastic resin having a melting point of 135 to 190°C. (3) The nonwoven fabric laminate for sound absorbing materials according to (1) or (2), wherein the staple fibers C1 have a fineness of 1.0 to 5.0 dtex. (4) The nonwoven fabric laminate for sound-absorbing materials according to any one of (1) to (3), wherein the thermoplastic resin having a melting point of 135 to 190° C. is a crystalline resin. (5) The nonwoven fabric laminate for sound-absorbing materials according to any one of (1) to (4), wherein the staple fibers C2 are core-sheath type composite staple fibers, and a resin constituting the sheath is a thermoplastic resin having a melting point of 70 to 190°C. (6) The nonwoven fabric laminate for sound-absorbing materials according to any one of (1) to (5), wherein the thermoplastic resin having a melting point of 70 to 190° C. is a noncrystalline resin. (7) The nonwoven fabric layer α has a basis weight of 100 g / m 2 More than 700g / m 2 The nonwoven fabric for sound absorbing materials according to any one of (1) to (6), wherein the nonwoven fabric layer α has a thickness of 7 mm or more and 40 mm or less. (8) The nonwoven fabric layer β has a basis weight of 30 g / m 2More than 120g / m 2 The nonwoven fabric for sound absorbing materials is described in any one of (1) to (7) below. (9) The nonwoven fabric for sound absorbing materials according to any one of (1) to (8), wherein the nonwoven fabric layer β has a tensile elongation at break of 50% or more and a static friction coefficient of 0.5 or less. (10) It is preferable that the nonwoven fabric for sound-absorbing materials according to any one of (1) to (9) is such that the staple fiber A, the staple fiber B, the staple fiber C1 and the staple fiber C2 are all polyester-based staple fibers, (11) A nonwoven fabric laminate for sound absorbing materials according to any one of (1) to (10) is used as a base material, and the air permeability is 3 to 50 cm 3 / cm 2 The nonwoven fabric layer γ for the surface is a sound-absorbing material laminated on the surface of the nonwoven fabric layer α of the nonwoven fabric laminate for sound-absorbing material. Effect of the Invention

[0011] According to the present invention, it is possible to provide a nonwoven fabric for sound absorbing material which has excellent thickness recovery during molding, excellent conformability to the complex shapes of automobile bodies, etc., and excellent sound absorbing performance. Furthermore, it is possible to obtain a sound absorbing material having a nonwoven fabric for sound absorbing material as a substrate and a nonwoven fabric layer for a skin. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The nonwoven fabric laminate for sound absorbing material of the present invention is formed by laminating a nonwoven fabric layer α and a nonwoven fabric layer β. The nonwoven fabric layer α contains short fibers A having a fineness of 0.4 to 3.8 dtex and short fibers B having a fineness of 4.0 to 22.0 dtex, the total content of short fibers A and B relative to the total mass of the nonwoven fabric layer α is 86 to 98 mass%, and the content ratio of short fibers A to short fibers B (short fiber A content / short fiber B content) is 0.05 to 3.80. The nonwoven fabric layer α further contains short fibers C1 having a resin with a melting point of 135 to 190°C in its outer surface layer, and the content of short fibers C1 relative to the total mass of the nonwoven fabric layer α is 2 to 14 mass%. The nonwoven fabric layer β contains short fibers C2 having a surface layer containing a resin having a melting point of 70 to 190° C., and the content by mass of the short fibers C2 relative to the total mass of the nonwoven fabric layer β is 20 to 60 mass %.

[0013] The nonwoven fabric layer α is a part that becomes part of the base material of the sound-absorbing material, and short fibers A, B, and C1 are uniformly mixed. The inclusion of short fiber A creates many fine holes, resulting in excellent sound-absorbing performance. Furthermore, short fiber B, which has a larger fineness than short fiber A, creates many fine holes and is highly rigid, contributing to thickness recovery during molding. By adjusting the mass ratio of short fiber A and short fiber B and mixing them uniformly, good sound-absorbing performance and thickness recovery during molding are achieved.

[0014] In other words, such a nonwoven fabric laminate for sound absorbing materials (hereinafter sometimes simply referred to as "nonwoven fabric") has excellent thickness recovery during molding due to the nonwoven fabric layer α having the above-mentioned configuration, even when heated and compressed during molding. The sound absorbing material can ensure a thickness sufficient for exhibiting sound absorbing performance, and excellent sound absorbing performance is achieved due to air friction in the fine porous parts inside the nonwoven fabric layer α.

[0015] Furthermore, by having the nonwoven fabric layer β having the above-mentioned configuration, it is possible to suppress the tearing of the nonwoven fabric layer due to friction between the nonwoven fabric laminate for sound absorbing material and the mold during heating and compression during molding, and it is possible to obtain a material that is excellent in conformity with the mold and moldable into the required shape. The nonwoven fabric layer β may be present on at least one side of the nonwoven fabric layer α, but it may be present on both sides. Since the sound absorbing material is provided with a skin material described later on the other side of the nonwoven fabric layer α during molding, by having the nonwoven fabric layer β on the side that comes into contact with the mold, it is possible to suppress the tearing of the nonwoven fabric layer, and it is possible to obtain a material that is excellent in conformity with the mold and moldable into the required shape.

[0016] Here, if the content of short fibers C1 in nonwoven fabric layer α is increased, the content of resin contained in short fibers C1 inside nonwoven fabric layer α increases, and the adhesive action when the resin melts and resolidifies at 135°C to 190°C reduces the thickness during molding, making it difficult to obtain thickness recovery. Therefore, in the present invention, by reducing the content of short fibers C1 in nonwoven fabric layer α and increasing the content of short fibers C2 in nonwoven fabric layer β, a nonwoven fabric for sound absorbing material that has good thickness recovery during molding and excellent sound absorbing performance can be obtained.

[0017] Then, the nonwoven fabric layer α and the nonwoven fabric layer β are laminated and the interface between them is partially fused to obtain a nonwoven fabric laminate. The "partial fusion" between the nonwoven fabric layer α and the nonwoven fabric layer β means that the resin contained in the outer surface layer of the short fibers C2 contained in the nonwoven fabric layer β is melted to bond a part of the short fibers A, B, or C1 of the nonwoven fabric layer α to the short fibers C2 and other short fibers of the nonwoven fabric layer β. In other words, the resin bonds the fibers together, mainly at the points where the monofilaments intersect, and the laminated surfaces are not entirely bonded, but are partially bonded.

[0018] It is important that the lamination state of the nonwoven fabric layer α and the nonwoven fabric layer β does not change at the interface between the nonwoven fabric layer α and the nonwoven fabric layer β during molding. If the lamination state changes, there is a concern that each nonwoven fabric layer may peel off or stack during molding, which in turn makes it difficult to maintain the sound absorbing performance. For this reason, the nonwoven fabric layer β is required to maintain the lamination state in addition to suppressing the tearing of the nonwoven fabric for sound absorbing material due to friction between the nonwoven fabric for sound absorbing material and the molding die during heating and compression during the above-mentioned molding. The short fibers C2 contained in the nonwoven fabric layer β bond a part of the short fibers of the laminated nonwoven fabric layer α and the nonwoven fabric layer β. For this reason, it is preferable that the melting point of the resin contained in the outer surface layer of the short fibers C2 contained in the nonwoven fabric layer β is lower than the melting point of the resin contained in the outer surface layer of the short fibers C1.

[0019] The nonwoven fabric layer α contains short fibers A having a fineness of 0.4 to 3.8 dtex and short fibers B having a fineness of 4.0 to 22.0 dtex. By containing short fibers A having a fineness of 0.4 to 3.8 dtex, a porous portion having a large number of fine holes can be formed inside the nonwoven fabric for sound absorption material, and the sound absorption performance of the sound absorption material using this nonwoven fabric is excellent.

[0020] By making the fineness of the short fibers A 0.4 dtex or more, thread breakage and winding around the card cloth are suppressed during the carding process in manufacturing the nonwoven fabric layer α, the short fibers A are uniformly dispersed in the nonwoven fabric layer α, and a porous portion having many fine holes can be formed inside the nonwoven fabric layer α, resulting in excellent sound absorption performance when used as a sound absorbing material. On the other hand, by making the fineness of the short fibers A 3.8 dtex or less, a porous portion having many fine holes can be formed inside the nonwoven fabric layer α by the short fibers A having a small fineness. As a result, when sound passes through the gaps between the fibers, i.e., the porous portion, the sound can be efficiently converted into heat by air friction with the fibers around the gaps, and excellent sound absorption can be obtained when used as a sound absorbing material. From the above point of view, the fineness of the short fibers A is preferably 0.5 to 2.0 dtex, more preferably 0.5 to 0.9 dtex.

[0021] Furthermore, the nonwoven fabric layer α of the nonwoven fabric laminate of the present invention contains short fibers B having a fineness of 4.0 to 22.0 dtex, and the rigidity of the short fibers B can impart thickness recovery properties to the nonwoven fabric of the present invention during molding. By making the fineness of the short fibers B 4.0 dtex or more, the rigidity of the short fibers B can impart thickness recovery properties to the nonwoven fabric of the present invention during molding. On the other hand, by making the fineness of the short fibers B 22.0 dtex or less, a porous portion having a large number of fine holes can be formed inside the nonwoven fabric layer α, and the sound absorbing performance when used as a sound absorbing material is excellent. From the above viewpoint, the fineness of the short fibers B is preferably 5.0 to 18.0 dtex, and particularly preferably 6.0 to 15.0 dtex.

[0022] The nonwoven fabric layer α of the nonwoven fabric laminate of the present invention is characterized in that the total content of short fiber A and short fiber B relative to the total mass of the nonwoven fabric layer α is 86 to 98 mass%, and the content mass ratio of short fiber A to short fiber B (content mass of short fiber A / content mass of short fiber B) is 0.05 to 3.80. By setting the total content and content mass ratio of short fiber A and short fiber B within the above ranges, it is possible to achieve both thickness recovery during molding and sound absorbing performance when used as a sound absorbing material. By setting the total content mass of short fiber A and short fiber B to 86 mass% or more, excessive fusion between fibers caused by short fiber C1 described later can be suppressed, and thickness recovery can be maintained even when heated or compressed during molding. As a result, a thickness for exhibiting sound absorbing performance, that is, a porous portion having fine holes is formed inside the nonwoven fabric layer α, resulting in excellent sound absorbing performance. On the other hand, by setting the total content of short fiber A and short fiber B to 98% by mass or less, the shape of the nonwoven fabric layer α can be maintained, and the nonwoven fabric for sound absorbing material can be easily transported and handled during molding. Furthermore, the loss of fibers when the sound absorbing material is cut can be reduced. From the above viewpoints, the total content of short fiber A and short fiber B is preferably 86 to 97% by mass, and particularly preferably 90 to 97% by mass.

[0023] Furthermore, by setting 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) to 0.05 to 3.80, it is possible to achieve both thickness recovery during molding and sound absorbing performance when used as a sound absorbing material. Since the nonwoven fabric layer α is made of a material in which the short fiber A, the short fiber B, and the short fiber C1 are mixed in advance, it is not a layer structure made of a specific short fiber, but a nonwoven fabric in which each of the constituent fibers is uniformly distributed inside the nonwoven fabric layer α.

[0024] Therefore, the short fiber A plays a role in forming a fine porous portion inside the nonwoven fabric layer α and improving the sound absorbing performance. In addition, the short fiber B plays a role in imparting thickness recovery during molding due to its rigidity. By setting the content mass ratio of the short fiber A to the short fiber B to 0.05 or more, it is possible to form a fine porous portion inside the nonwoven fabric layer α and improve the sound absorbing performance. On the other hand, by setting the content mass ratio of the short fiber A to the short fiber B to 3.80 or less, it is possible to impart thickness recovery during molding due to the rigidity of the short fiber B, and it is possible to form a thickness, i.e., a porous portion, for exhibiting sound absorbing performance. In addition, by including a relatively thick short fiber B at a certain mass ratio, even when the fineness of the short fiber A is thin, the short fiber A is prevented from breaking or being wound around the carding cloth during the carding process, and the short fiber A is uniformly dispersed, and a fine porous portion can be formed inside the nonwoven fabric layer α, resulting in excellent sound absorbing performance when used as a sound absorbing material. From the above viewpoints, the content mass ratio of short fibers A to short fibers B is preferably from 0.20 to 2.20, and particularly preferably from 0.30 to 1.40.

[0025] The nonwoven fabric layer α of the nonwoven fabric laminate of the present invention contains short fibers C1 containing a resin having a melting point of 135 to 190°C, and the content of the short fibers C1 with respect to the total mass of the nonwoven fabric 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 above ranges, it is possible to achieve both thickness recovery during molding, ease of transport and handling of the nonwoven fabric for sound absorbing material, and reduction in fiber dropout when the sound absorbing material is cut. By setting the melting point of the resin contained in the short fibers C1 to 135°C or higher, it is possible to suppress fusion of the constituent fibers of the nonwoven fabric layer α by the short fibers C1 in the stage of producing the nonwoven fabric layer α, and it is possible to maintain thickness recovery even when heated or compressed during molding. On the other hand, by setting the melting point of the resin contained in the short fibers C1 to 190°C or less, in the stage of producing the nonwoven fabric layer α, the constituent fibers of the nonwoven fabric layer α are fused by the short fibers C1, which improves the transport and handling properties of the nonwoven fabric for sound absorbing material, and further reduces the loss of fibers when the sound absorbing material is cut. From this point of view, the melting point of the resin contained in the short fibers C1 is preferably 140 to 180°C, and particularly preferably 145 to 170°C.

[0026] In addition, by making the content of the short fibers C1 2% by mass or more relative to the total mass of the nonwoven fabric layer α, the constituent fibers of the nonwoven fabric layer α are fused by the short fibers C1 in the stage of producing the nonwoven fabric layer α, which improves the transport and handling properties of the nonwoven fabric for sound absorbing material, and further reduces the loss of fibers when the sound absorbing material is cut. On the other hand, by making the content of the short fibers C1 14% by mass or less relative to the total mass of the nonwoven fabric layer α, the fusion points of the short fibers C1 and the short fibers A and the fusion points of the short fibers C1 and the short fibers B during heating and compression during molding can be reduced, and thickness recovery can be maintained even during heating and compression during molding. From the above-mentioned viewpoint, the content of the short fibers C1 relative to the total mass of the nonwoven fabric layer α is preferably 3 to 12% by mass, and particularly preferably 3 to 10% by mass.

[0027] The nonwoven fabric layer β of the nonwoven fabric laminate of the present invention contains short fibers C2 that contain a resin with a melting point of 70 to 190° C. in the outer surface layer, and the content of the short fibers C2 with respect to the total mass of the nonwoven fabric layer β is characterized in that it is 20 to 60 mass%. The short fibers C2 are not particularly specified and any known fiber can be used, such as side-by-side composite fibers in which a low melting point component and a high melting point component are bonded together, or core-sheath composite fibers in which a high melting point component is covered with a low melting point component.

[0028] The nonwoven fabric layer β contains 40 to 80 mass % of other short fibers. Thermoplastic resins such as polyester resins, polyamide resins, acrylic resins, and polyolefin resins can be used as the material for the other short fibers. Among these, short fibers made of polyester resins are preferred because they have excellent heat resistance, that is, they can reduce deformation and discoloration of the nonwoven fabric for sound absorbing material in a high-temperature environment when used near the engine room of an automobile or the like.

[0029] By setting the melting point of the resin of the outer surface layer contained in the short fibers C2 and the content of the short fibers C2 within the above ranges, the smoothness of the nonwoven fabric layer β is increased, and the breakage of the nonwoven fabric for sound absorbing material due to friction between the nonwoven fabric for sound absorbing material and the mold during molding can be suppressed, and it becomes possible to mold it into a required shape. Furthermore, in the manufacturing process of the nonwoven fabric for sound absorbing material, the nonwoven fabric layer α and the nonwoven fabric layer β can be easily bonded, and productivity can be improved. By setting the melting point of the resin contained in the short fibers C2 to 70°C or higher, adhesion of the resin with a melting point of 70 to 190°C to the manufacturing device in the process of manufacturing the nonwoven fabric layer β can be eliminated, and productivity can be improved. On the other hand, by setting the melting point of the resin contained in the short fibers C2 to 190°C or lower, in the stage of manufacturing the nonwoven fabric layer β, the smoothness of the nonwoven fabric layer β can be increased by the fusion of the fibers by the short fibers C2, and the breakage of the nonwoven fabric for sound absorbing material due to friction between the nonwoven fabric for sound absorbing material and the mold during heating and compression during molding can be suppressed.

[0030] It is presumed that the nonwoven fabric layer β has a lower basis weight and less fluffy fibers than the nonwoven fabric layer α, and the resin in the outer surface layer of the short fibers C2 melts and fills the unevenness of the nonwoven fabric surface, making the surface smooth. In this respect, the melting point of the resin contained in the short fibers C2 is preferably 70 to 180°C, and particularly preferably in the range of 70 to 170°C. In addition, by making the content of the short fibers C2 to be 20% by mass or more relative to the total mass of the nonwoven fabric layer β, the nonwoven fabric layer β becomes smooth due to the fusion of the fibers by the short fibers C2, and tearing of the nonwoven fabric for sound absorbing material due to friction between the nonwoven fabric for sound absorbing material and the molding die during heating and compression during molding can be suppressed. Furthermore, in the manufacturing process of the nonwoven fabric laminate for sound absorbing material, the nonwoven fabric layer α and the nonwoven fabric layer β can be easily partially fused due to the fusion of the short fibers C2 and the short fibers contained in the nonwoven fabric layer α, thereby improving productivity. On the other hand, by making the content of the short fibers C2 to be 60% by mass or less with respect to the total mass of the nonwoven fabric layer β, the tensile breaking elongation of the nonwoven fabric layer β can be improved, the conformability of the nonwoven fabric layer β to the molding die can be improved, and the breakage of the nonwoven fabric layer β can be suppressed. From the above viewpoint, the content of the short fibers C2 to the total mass of the nonwoven fabric layer β is preferably 25 to 50% by mass, more preferably 25 to 40% by mass. The smoothness can be measured by the static friction coefficient according to JIS P8147:1994 3.2 inclination method.

[0031] If the static friction coefficient on the surface of the nonwoven fabric β of the nonwoven fabric laminate exceeds 0.5, the friction between the nonwoven fabric for sound absorbing material and the mold increases during heating and compression during molding, causing wrinkles and tears on the surface of the nonwoven fabric, resulting in poor sound absorbing performance and quality, which is undesirable. Therefore, the static friction coefficient is preferably 0.5 or less.

[0032] In addition, the short fibers C1 contained in the nonwoven fabric layer α of the nonwoven fabric laminate of the present invention are preferably core-sheath type composite short fibers, and the resin constituting the sheath part is preferably a resin having a melting point of 135 to 190°C. The sheath part of the core-sheath type composite short fibers corresponds to the outer surface layer. The short fibers C1 are core-sheath type composite fibers, and the fibers contained in the nonwoven fabric layer α can be bonded together by the adhesive action of the resin contained in the sheath part. In addition, by setting the melting point of the resin constituting the sheath part to 135°C or more, excessive adhesion between the fibers caused by the short fibers C1 can be suppressed, and the thickness recovery can be improved even when heated or compressed during molding. On the other hand, by setting the melting point of the resin constituting the sheath part to 190°C or less, in the stage of producing the nonwoven fabric layer α, the short fibers C1 can fuse together to improve the transport and handling properties of the nonwoven fabric for sound absorbing material, and further reduce the falling off of fibers when the sound absorbing material is cut. From the above viewpoints, the melting point of the resin constituting the sheath is preferably 140 to 180°C, and particularly preferably 145 to 170°C.

[0033] The fineness of the short fibers C1 is preferably 1.0 to 5.0 dtex. By making the fineness of the short fibers C1 1.0 dtex or more, the short fibers C1 are prevented from breaking or winding around the card cloth in the carding process when the nonwoven fabric layer α is manufactured, and the short fibers C1 are uniformly dispersed. The short fibers C1 are fused to each other, which improves the transportability and handling of the nonwoven fabric for sound absorption material, and further reduces the falling off of fibers when the sound absorption material is cut. On the other hand, by making the fineness of the short fibers C1 5.0 dtex or less, the number of fusion points between the short fibers C1 and the short fibers A and B is increased, which improves the transportability and handling of the nonwoven fabric for sound absorption material, and further reduces the falling off of fibers when the sound absorption material is cut. From the above-mentioned viewpoint, the fineness of the short fibers C1 is preferably 1.4 to 4.0 dtex, and particularly preferably 1.6 to 3.0 dtex.

[0034] In addition, when the short fibers C1 are core-sheath type composite short fibers and the resin constituting the sheath is a thermoplastic resin having a melting point of 135 to 190°C, it is preferably a crystalline resin. By using a crystalline thermoplastic resin as the resin contained in the short fibers C1, even if the content of the short fibers C1 relative to the total mass of the nonwoven fabric layer α is as small as 2 to 14 mass%, the fusion between the crystalline resin and the short fibers A and B becomes stronger, improving the transport and handling of the nonwoven fabric for sound absorbing material, and reducing fiber dropout when the sound absorbing material is cut. In addition, since the content of the short fibers C1 can be reduced as described above, the fusion points between the short fibers C1 and the short fibers A and B during heating and compression during molding can be reduced, and thickness recovery can be maintained even during heating and compression during molding. A preferred example of such a crystalline resin is a polyester copolymer resin.

[0035] In the present invention, a crystalline resin is defined as a resin that has a glass transition point, an exothermic peak due to crystallization (crystallization point), and an endothermic peak due to melting (melting point) in differential scanning calorimetry, while a non-crystalline resin is defined as a resin that has only a glass transition point and does not have a clear endothermic peak due to melting (melting point).

[0036] On the other hand, the short fibers C2 are preferably core-sheath type composite short fibers, and the resin constituting the sheath is a thermoplastic resin having a melting point of 70 to 190°C. The sheath of the core-sheath type composite short fibers corresponds to the outer surface layer. The resin constituting the sheath is preferably a thermoplastic resin having a melting point of 70 to 190°C, and is preferably a non-crystalline resin. A preferred example of such a non-crystalline resin is a polyester copolymer resin.

[0037] As the material for the staple fiber A, staple fiber B, staple fiber C1, and staple fiber C2 of the present invention, thermoplastic resins such as polyester resins, polyamide resins, acrylic resins, and polyolefin resins can be used. Among these, staple fibers made of polyester resins (hereinafter referred to as polyester staple fibers) are preferred because they have excellent heat resistance, that is, they can reduce deformation and discoloration of the nonwoven fabric for sound absorbing material in a high-temperature environment when used near the engine room of an automobile or the like. Furthermore, as for staple fibers A and B, staple fibers made of polyethylene terephthalate resin (hereinafter referred to as polyethylene terephthalate staple fibers) are preferred, which are particularly excellent in heat resistance among polyester resins.

[0038] The weight of the nonwoven fabric layer α of the present invention is 100 g / m 2 More than 700g / m 2 The thickness of the nonwoven fabric layer α is preferably 7 mm or more and 40 mm or less. 2 By setting the nonwoven fabric layer α at 700 g / m or more, the thickness recovery can be improved even when heated or compressed during molding, and many porous parts having fine holes are formed inside the nonwoven fabric layer α, resulting in excellent sound absorbing performance. 2 By setting the weight of the nonwoven fabric layer α to 150 g / m2, a nonwoven fabric for sound absorbing material having excellent lightness can be obtained. 2 More than 550g / m 2 It is preferable that the thickness is less than 200 g / m 2 More than 400g / m 2 It is particularly preferable that the thickness of the nonwoven fabric layer α is 7 mm or more. In addition, by making the thickness of the nonwoven fabric layer α 7 mm or more, the thickness recovery can be improved even when heated or compressed during molding. On the other hand, by making the thickness of the nonwoven fabric layer α 40 mm or less, the transportation efficiency of the nonwoven fabric for sound absorbing material and the transportation efficiency during molding can be facilitated. From the above viewpoints, the thickness of the nonwoven fabric 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.

[0039] The weight of the nonwoven fabric layer β is 30 g / m 2More than 120g / m 2 The weight of the nonwoven fabric layer β is preferably 30 g / m or less. 2 By setting the nonwoven fabric layer B at the above value, the smoothness of the nonwoven fabric layer B can be increased, and the breakage of the nonwoven fabric for sound absorbing material caused by friction between the nonwoven fabric for sound absorbing material and the molding die during heating and compression during molding can be suppressed. 2 By setting the weight per unit area of ​​the nonwoven fabric layer β to 40 g / m2, a nonwoven fabric for sound absorbing material having excellent lightness can be obtained. 2 More than 100g / m 2 It is preferable that the thickness is less than 45 g / m 2 More than 80g / m 2 It is particularly preferred that:

[0040] The tensile breaking elongation of the nonwoven fabric layer β is preferably 50% or more. By making the tensile breaking elongation 50% or more, the nonwoven fabric layer β can improve the conformability to the mold and prevent the nonwoven fabric layer β from breaking. From the above-mentioned viewpoint, the tensile breaking elongation is preferably 55% or more, and more preferably 60% or more. As a means for improving the tensile breaking elongation of the nonwoven fabric layer β, as described above, a means for improving the entanglement of the short fibers contained in the nonwoven fabric layer β can be adopted by adjusting the content mass of the short fibers C2 or adopting a needle punching process or a spunlace process in the production of the nonwoven fabric layer β. The tensile breaking elongation of the present invention can be measured in accordance with JIS L 1913:1998 6.3.1, and the average value of the tensile breaking elongation in an arbitrary direction and in a direction perpendicular to the arbitrary direction can be calculated and measured.

[0041] Next, a preferred method for producing the nonwoven fabric for sound absorbing material of the present invention will be described. The preferred method for producing the nonwoven fabric of the present invention has the following steps.

[0042] <Nonwoven fabric layer α> (a) A process for spreading staple fibers A, B, and C1 (b) A process of forming the staple fibers A, B, and C1 into a web. <Nonwoven fabric layer β> (c) A step of opening the short fibers C2 and other short fibers (d) A step of forming the short fibers C2 and other short fibers into a web. (e) A step of entangling the short fibers C2 with other short fibers by needles or water jets to obtain a nonwoven fabric layer β <Nonwoven fabric laminate for sound absorbing material> (f) A process of laminating a web containing the staple fiber A, the staple fiber B, and the staple fiber C1 with the nonwoven fabric layer β to obtain a laminate. (g) A process of melting the short fibers C1 by hot air to obtain the nonwoven fabric layer α and melting the short fibers C2 to fuse the nonwoven fabric layer α and the nonwoven fabric layer β together. The steps (a) to (g) will be described in detail below.

[0043] <Nonwoven fabric layer α> First, (a) the process of opening staple fibers A, B, and C1 (opener process) will be described. In the opener process, staple fibers A, B, and C1 (hereinafter also referred to as individual staple fibers) are weighed so that the contents of staple fibers A, B, and C1 in the nonwoven fabric layer α are as desired, and then the staple fibers are sufficiently opened and mixed using air or the like.

[0044] Next, (b) the process of forming the staple fibers A, B, and C1 into a web (carding process) will be described. In the carding process, the mixed staple fibers obtained in the opener process are aligned with clothed rollers to obtain a web. In other words, the web is a membrane-like sheet made only of fibers, and is also called a fleece.

[0045] <Nonwoven fabric layer β> (c) The step of opening the staple fibers C2 and other staple fibers is similar to the step (a) above, in which the staple fibers C2 and other staple fibers are weighed in an opener step, and then the respective staple fibers are sufficiently opened and mixed using air or the like.

[0046] In addition, in the process of (d) forming a web from the staple fiber C2 and other staple fibers, similar to the process (b) above, the mixed staple fibers obtained in the opener process are drawn together by a clothed roller in a carding process to obtain a web.

[0047] Next, (e) a step of entangling the short fibre C2 with other short fibres by needles or water streams to obtain a nonwoven fabric layer β (entangling step) will be described. In the entangling step, the short fibres are entangled with each other by a mechanical entangling method using a needle punch method or a water jet punch method (water stream entangling method). In such an entangling step, by entangling the short fibre C2 with other short fibres, the tensile breaking elongation of the nonwoven fabric layer β can be improved, the ability of the nonwoven fabric layer β to conform to the molding die can be improved, and breakage of the nonwoven fabric layer β can be suppressed. Of the above two methods, the needle punch method is preferred for the entangling step in terms of productivity, and the needle density is preferably 30 to 300 needles / cm. 2 By setting the needle density at 30 needles / cm, the tensile elongation at break of the nonwoven fabric layer β can be improved, the ability of the nonwoven fabric layer β to conform to the mold can be improved, and the breakage of the nonwoven fabric layer β can be suppressed. 2 By setting the needle density at 300 needles / cm or more, the nonwoven fabric layer β is entangled, and the tensile elongation at break can be improved. 2 By setting the needle density at 50 to 200 needles / cm or less, it is possible to suppress breakage of the short fibers caused by the needles and improve the tensile elongation at break. 2 It is preferable to set the density to 50 to 150 fibers / cm. 2 It is particularly preferable that:

[0048] <Nonwoven fabric laminate for sound absorbing material> (f) In the step of laminating a web containing staple fiber A, staple fiber B, and staple fiber C1 with a nonwoven fabric layer β to obtain a laminated web, a method is preferably adopted in which the nonwoven fabric layer β is laminated while a web containing staple fiber A, staple fiber B, and staple fiber C1 is produced.

[0049] As for the step (g) of melting the short fibers C1 with hot air to obtain the nonwoven fabric layer α and melting the short fibers C2 to fuse the nonwoven fabric layer α and the nonwoven fabric layer β, hot air at 150 to 220°C is passed through the laminate in the thickness direction by a thermal bonding method to melt the short fibers C1 to obtain the nonwoven fabric layer α and melt the short fibers C2 to fuse the nonwoven fabric layer α and the nonwoven fabric layer β, thereby efficiently producing the nonwoven fabric for sound absorption of the present invention.

[0050] Next, the sound absorbing material will be described. The sound absorbing material comprising the nonwoven fabric laminate for sound absorbing material of the present invention is a material comprising the nonwoven fabric laminate for sound absorbing material of the present invention and a sheet having an air permeability of 3 to 50 cm3 as a surface material. 3 / cm 2 It is preferable that the nonwoven fabric for the skin is laminated on the surface side of the nonwoven fabric layer α of the nonwoven fabric for the sound absorbing material. The sound absorbing material having the structure of the skin material / nonwoven fabric layer α / nonwoven fabric layer β is arranged so that the skin material faces the sound incident side, thereby improving the sound absorbing performance of the sound absorbing material. 3 / cm 2 By setting the air permeability of the skin to 35 cm / s or more, sound can penetrate into the sound-absorbing material, and the air friction of the skin and the air friction of the nonwoven fabric for the sound-absorbing material can improve the sound absorption performance. 3 / cm 2 By setting the air permeability of the skin material to 4 to 40 cm / s or less, the sound absorbing performance can be improved by resonance between the membrane vibration of the skin material and the air vibration in the fine porous portion of the sound absorbing nonwoven fabric. 3 / cm 2 / s is preferable, and 5 to 30 cm 3 / cm 2 The air permeability of the skin material is measured in accordance with JIS L 1096-1999 8.27.1 Method A (Fragile type method).

[0051] The preferred configuration of the sound-absorbing material is as described above. However, in addition to the surface nonwoven fabric having the above-mentioned specific air permeability, any other material that can provide the effect of the surface material due to the air friction or resonance action described above can be used as the sound-absorbing material by laminating a general needle-punched nonwoven fabric, spunlace nonwoven fabric, spunbond nonwoven fabric, meltblown nonwoven fabric, woven or knitted fabric, fiber board, or foam on the surface of the nonwoven fabric layer α of the sound-absorbing nonwoven fabric. EXAMPLES

[0052] The evaluation and measurement methods used in the examples are described below.

[0053] (1) Measurement of the content of each short fiber that constitutes the nonwoven fabric laminate for sound absorption The nonwoven fabric layers α and β were separated, and the correct blend ratio (mass ratio of each fiber under standard conditions) was measured for each nonwoven fabric based on JIS L 1030-1:2006 "Test method for blend ratio of textile products - Part 1: Fiber identification" and JIS L 1030-2:2005 "Test method for blend ratio of textile products - Part 2: Fiber blend ratio", and this was taken as the content (mass%) of each fiber constituting the nonwoven fabric laminate for sound absorption. In this way, the fiber materials constituting the nonwoven fabric layers α and β of the nonwoven fabric laminate for sound absorption and their content (mass%) were identified.

[0054] (2) Measurement of the fiber fineness and mass content of the fibers constituting the nonwoven fabric laminate for sound absorption The cross sections of the residual nonwoven fabrics of the nonwoven fabric layers α and β in 6. Dissolution method of JIS L 1030-2:2005 "Test method for blending ratio of textile products - Part 2: Fiber blending ratio" mentioned above (1) were observed with a scanning electron microscope (SEM) (Hitachi High-Tech S-3500N type), 30 observation areas were randomly selected, and cross-sectional photographs were taken at a magnification of 1000 times. Furthermore, the diameters of the single fibers were measured for all fibers present in the cross-sectional photographs. At this time, fibers that were observed to be fused in the cross-sectional photographs were clearly distinguished from fibers that were not observed to be fused. The measurement was performed on fibers that were not observed to be fused. In addition, when the cross-sectional shape of the fiber was an irregular cross-sectional shape, the cross-sectional area of ​​the fiber was measured from the cross-sectional photograph, and the cross-sectional area was converted to a perfect circular diameter to obtain the single fiber diameter of the fiber. Among the obtained data, for fibers in which no fusion was observed, the single fiber diameter data was classified into intervals of 0.1 μm, and the average single fiber diameter and the number of fibers in each interval were tallied. The fiber fineness in each interval was calculated from the average single fiber diameter in each interval and the specific gravity of each fiber specified in (1) above, using formula (1). Fineness (dtex) = (average single fiber diameter (μm) / 2) 2 x 3.14 x fiber specific gravity / 100 Equation (1).

[0055] For the nonwoven fabric layer α, the content (mass%) of fibers having a fineness of 0.4 to 3.8 dtex was calculated from the fineness of each section, the number of fibers in each section, and the specific gravity of the fiber material using formula (2).

[0056] Mass content of fibers with a fineness of 0.4 to 3.8 dtex (mass%) = ((fineness (dtex) of fibers with a fineness of 0.4 to 3.8 dtex in each section (dtex) × number of fibers (pieces) in each section)) / (fineness (dtex) of fibers other than 0.4 to 3.8 dtex in each section (dtex) × number of fibers (pieces) in each section) × 100 Formula (2).

[0057] In the same manner, the mass content (mass%) of fibers having a fineness of 4.0 to 22.0 dtex was determined. The fineness and mass content (mass%) of fibers in which fusion was observed were also determined in the same manner. In the nonwoven fabric layer β, fibers in which fusion was observed and fibers in which fusion was not observed were similarly distinguished, and measurements were performed on fibers in which fusion was not observed. The fineness and mass content (mass%) of each fiber were determined.

[0058] In addition, when the nonwoven fabric layer α or the nonwoven fabric layer β constituting the nonwoven fabric for sound-absorbing material contained multiple fibrous materials, the above-mentioned measurements of fineness and content were carried out for each fibrous material using the residual nonwoven fabric in the dissolution method, and the fineness and content of the fibers constituting the nonwoven fabric for sound-absorbing material were determined.

[0059] (3) Measurement of the melting point of short fibers The nonwoven fabric layer α and the nonwoven fabric layer β were each measured at a heating rate of 10°C / min under a nitrogen gas flow using a Shimadzu Differential Scanning Calorimeter: DSC-60 manufactured by Shimadzu Corporation, and the melting endothermic peak temperature (°C) of the obtained DSC curve was taken as the melting point (°C) of the short fibers of each nonwoven fabric layer constituting the sound-absorbing nonwoven fabric laminate. The nonwoven fabric layer α and the nonwoven fabric layer β contain multiple short fibers, and each peak was taken as the melting point of the short fibers constituting each nonwoven fabric layer. In addition, for resins that are amorphous and cannot confirm the melting endothermic peak by DSC, a melting point microscope was used to observe the melting start temperature and melting completion temperature at a heating rate of 10°C / min, and the melting point was calculated by formula (3). Melting point (°C) = (melting start temperature (°C) + melting completion temperature (°C)) / 2 Equation (3).

[0060] (4) Measurement of the basis weight of the nonwoven fabric layer α, the nonwoven fabric layer β, and the nonwoven fabric laminate for sound absorbing material Measurements were performed based on JIS L 1913:1998 6.2. Nonwoven fabric layer α and nonwoven fabric layer β were separated from the sound-absorbing nonwoven fabric, and three test pieces measuring 200 mm × 200 mm were taken from each sample. The mass of the test pieces in standard conditions was measured, and the basis weight, which is the mass per unit area, was calculated using formula (4), and the average value was calculated for each of nonwoven fabric layer α and nonwoven fabric layer β.

[0061] ms=m / S formula (4) ms: mass per unit area (g / m 2 ) m: Average mass (g) of the test pieces of nonwoven fabric layer α or nonwoven fabric layer β S: Area of ​​the test piece of nonwoven fabric layer α or nonwoven fabric layer β (m 2 ) The basis weight of the sound-absorbing nonwoven fabric was the total basis weight of the nonwoven fabric layer α and the nonwoven fabric layer β.

[0062] (5) Measurement of the thickness of nonwoven fabric layer α, nonwoven fabric layer β, and sound-absorbing nonwoven fabric The nonwoven fabric layer α and the nonwoven fabric layer β were separated from the sample of the nonwoven fabric for sound absorption, and five test pieces of 200 mm × 200 mm were taken. A ruler was placed on the cross section of the test piece, and the thicknesses of the nonwoven fabric layer α and the nonwoven fabric layer β were measured. Measurements were performed for each test piece (five pieces), and the average value was calculated. Note that the thickness of the nonwoven fabric for sound absorption was measured as above without separating the nonwoven fabric layer α and the nonwoven fabric layer β.

[0063] (6) Measurement of tensile breaking elongation of nonwoven fabric layer β Measurement was performed based on JIS L 1913:1998 6.3.1. The nonwoven fabric layer β was separated from the sound-absorbing nonwoven fabric, and five test pieces with a width of 50 mm and a length of 200 mm were taken in one arbitrary direction. In addition, five test pieces with a width of 50 mm and a length of 200 mm were taken in a direction perpendicular to the above arbitrary direction. A load was applied to the obtained test pieces (total of 10 pieces) using a constant-speed extension tensile tester under the conditions of a gripping distance of 100 mm and a pulling speed of 200 mm / min until the test pieces broke, and the tensile breaking elongation (%) at the time of break was measured. The measurement was performed on 10 test pieces, and the average value was calculated. In terms of evaluation, the higher the tensile breaking elongation, the better the molding followability.

[0064] (7) Measurement of the static friction coefficient of nonwoven fabric for sound absorption Measurements were performed according to JIS P8147:1994 3.2 Inclination method. Five test pieces with a width of 250 mm and a length of 100 mm were taken from the nonwoven fabric for sound absorption in one arbitrary direction. In addition, five test pieces with a width of 250 mm and a length of 100 mm were taken in a direction perpendicular to the above arbitrary direction. The obtained test pieces (10 pieces in total) were attached to the inclined plate of the slip slope angle measuring device so that the long side of the test piece and the long side of the inclined plate were parallel and the nonwoven fabric layer β was on the upper surface. Next, a metal weight (width 60 mm, length 100 mm, mass 1000 g) was placed on the test piece so that the long side of the test piece and the long side of the weight were parallel to each other.

[0065] The measurement was performed by tilting the inclined plate at an inclination angle of less than 3° / sec, reading the inclination angle when the weight fell, and taking the tangent (tanθ) of the inclination angle as the static friction coefficient. Measurements were performed on 10 test pieces, and the average value was calculated. In terms of evaluation, the smaller the static friction coefficient value, the better the smoothness.

[0066] (8) Evaluation of thickness recovery during molding of nonwoven fabric for sound absorption Five test pieces with a width of 500 mm, a length of 500 mm, and a thickness of 30 mm (25 mm in Comparative Example 12) were taken from the nonwoven fabric for sound absorption in any one direction. The end of the test piece was fixed with a clamping metal fitting, and the upper and lower surfaces of the test piece were heated with a far-infrared heater heated to 220°C until the internal temperature of the nonwoven fabric for sound absorption reached 150°C. Then, the heated test piece was quickly moved and pressed between metal platens with a temperature of 20°C, a size of 400 x 400 mm, a pressure of 800 kPa, and a time of 60 seconds. The test piece after the pressing was cut into a size of 300 x 300 mm, a metal ruler was placed on the cross section of the test piece, and the thickness (mm) immediately after pressing was measured. The measurement was performed on five test pieces, and the average value was calculated by dividing the thickness (mm) before pressing. The larger the value, the better the thickness recovery during molding.

[0067] (9) Evaluation of fiber loss during cutting of sound-absorbing nonwoven fabric The center of the test piece (300 x 300 mm) after pressing prepared in (8) above was cut using scissors to a cutting length of 300 mm, and all of the fallen fibers were collected and their mass (mg) was measured using an electronic balance and converted to a cutting length of 1 m using the following formula (5), which was the amount of fiber loss at cutting (mg / m). Measurements were performed on five test pieces, and the average value was calculated and cut. The smaller the value of the amount of fiber loss at cutting, the less fibers were lost at cutting, and the better the result. Amount of fiber loss during cutting (mg / m) = mass of fallen fibers (mg) / cutting length (m) Equation (5).

[0068] (10) Measurement of normal incidence sound absorption coefficient of sound absorbing material Measurements were performed in accordance with the normal incidence sound absorption measurement method (in-pipe method) of JIS A 1405 (1998). Three circular test pieces 1 with a diameter of 92 mm were taken from the pressed test piece (300 × 300 mm) prepared in (8) above. Next, a nonwoven fabric for the surface (basis weight 250 g / m2) consisting of 40% by mass of 0.9 dtex polyethylene terephthalate (PET) short fibers and 60% by mass of 2.2 dtex polyethylene terephthalate (PET) short fibers was used. 2 , thickness 1.4mm, Fragile breathability 24cm 3 / cm2 / s), three circular test pieces 2 each having a diameter of 92 mm were taken. Furthermore, the test piece 2 was laminated on the surface of the nonwoven fabric layer α of the test piece 1.

[0069] The test equipment used was an automatic normal incidence sound absorption coefficient measuring instrument (model 10041A) manufactured by Denshi Sokki Co., Ltd. The test piece was attached to one end of the impedance tube for measurement so that test piece 2 was the sound incident side, and the normal incidence sound absorption coefficient was measured. The sound absorption coefficient for each frequency was calculated by multiplying the measured sound absorption coefficient by 100. The average value of the obtained sound absorption coefficient at 1000 Hz was taken as the low frequency sound absorption coefficient (%), and the average value of the obtained sound absorption coefficient at 2000 Hz was taken as the high frequency sound absorption coefficient (%).

[0070] <Example 1> In Example 1, the following nonwoven fabric laminate was used. (Nonwoven fabric layer α) As staple fiber A, 35 mass% of polyethylene terephthalate (PET) staple fiber having a fineness of 0.6 dtex and a melting point of 255°C was used, as staple fiber B, 60 mass% of polyethylene terephthalate (PET) staple fiber having a fineness of 6.6 dtex and a melting point of 255°C was used, and as staple fiber C1, 5 mass% of core-sheath staple fiber (core-sheath ratio 1:1) having a fineness of 2.2 dtex, a core made of polyethylene terephthalate (PET) having a melting point of 255°C and a sheath made of a crystalline copolymer polyester having a melting point of 160°C was used. Each staple fiber was subjected to an opener process and then a carding process to obtain a web.

[0071] (Nonwoven fabric layer β) The staple fibers were 70% by mass of polyethylene terephthalate (PET) staple fibers with a fineness of 6.6 dtex and a melting point of 255°C, and the staple fibers C2 were 30% by mass of core-sheath staple fibers (core-sheath ratio 1:1) with a fineness of 4.4 dtex, a core made of polyethylene terephthalate (PET) with a melting point of 255°C, and a sheath made of amorphous copolymer polyester with a melting point of 110°C. Each staple fiber was subjected to an opener process, a carding process, and then a needle punching process (needle density 100 / cm). 2 ) to obtain a needle-punched nonwoven fabric.

[0072] (Nonwoven fabric laminate for sound absorption) The web of the nonwoven fabric layer β and the needle-punched nonwoven fabric of the nonwoven fabric layer β are laminated and subjected to a thermal bonding process (hot air temperature 180°C). The nonwoven fabric layer α has a staple fiber A and staple fiber B content of 95 mass%, a staple fiber A to staple fiber B content ratio of 0.58, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 From the 5 mm thick laminate, a 30 mm thick nonwoven fabric laminate for sound absorbing material was obtained.

[0073] The nonwoven fabric laminate for sound absorbing material of Example 1 had a high tensile elongation at break of the nonwoven fabric layer β and excellent conformability, and the nonwoven fabric for sound absorbing material had a low static friction coefficient and excellent smoothness. In addition, the thickness after pressing was large, the thickness recovery during molding was excellent, and the amount of fiber loss during cutting was small, which was good. Furthermore, the low frequency sound absorption coefficient and high frequency sound absorption coefficient of the laminated nonwoven fabric for sound absorbing material were high.

[0074] <Example 2> The nonwoven fabric layer α was processed under the same process and conditions as in Example 1, except that the staple fiber A in the nonwoven fabric layer α was changed to a polyethylene terephthalate (PET) staple fiber having a fineness of 2.2 dtex and a melting point of 255°C. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 95% by mass, a mass ratio of staple fiber A to staple fiber B of 0.58, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric for sound absorption material was obtained from the nonwoven fabric having a thickness of 5 mm. The configuration and evaluation results of the nonwoven fabric for sound absorption material of Example 2 are shown in Table 1.

[0075] <Example 3> The nonwoven fabric layer α was processed under the same process and conditions as in Example 1, except that the staple fiber A in the nonwoven fabric layer α was changed to a polyethylene terephthalate (PET) staple fiber having a fineness of 3.3 dtex and a melting point of 255°C. The mass content of staple fiber A and staple fiber B in the nonwoven fabric layer α was 95 mass%, the mass ratio of staple fiber A to staple fiber B was 0.58, and the basis weight was 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the laminate with a thickness of 5 mm. The composition of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 1.

[0076] <Example 4> The nonwoven fabric layer α was processed under the same process and conditions as in Example 1, except that the staple fiber B in the nonwoven fabric layer α was changed to a polyethylene terephthalate (PET) staple fiber having a fineness of 14.4 dtex and a melting point of 255°C. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 95% by mass, a content ratio of staple fiber A to staple fiber B of 0.58, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the laminate with a thickness of 5 mm. The composition of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 1.

[0077] <Example 5> The nonwoven fabric layer α was processed under the same steps and conditions as in Example 1, except that the staple fiber A in Example 1 was used as the staple fiber A in the nonwoven fabric layer α, the staple fiber B in Example 1 was used as the staple fiber B, and the staple fiber C1 in Example 1 was used as the staple fiber C1 in the nonwoven fabric layer α, and the mass contents were changed to 36 mass%, 62 mass%, and 2 mass%, respectively. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 98 mass%, a mass ratio of staple fiber A to staple fiber B of 0.58, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the laminate with a thickness of 5 mm. The composition of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 1.

[0078] <Example 6> The nonwoven fabric layer α was processed under the same steps and conditions as in Example 1, except that the staple fiber A in Example 1 was used as the staple fiber A in the nonwoven fabric layer α, the staple fiber B in Example 1 was used as the staple fiber B, and the staple fiber C1 in Example 1 was used as the staple fiber C1 in the nonwoven fabric layer α, and the mass contents were changed to 34 mass%, 58 mass%, and 8 mass%, respectively. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 92 mass%, a mass ratio of staple fiber A to staple fiber B of 0.59, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the laminate with a thickness of 5 mm. The composition of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 1.

[0079] <Example 7> The nonwoven fabric layer α was processed under the same steps and conditions as in Example 1, except that the staple fiber A in Example 1 was used as the staple fiber A in the nonwoven fabric layer α, the staple fiber B in Example 1 was used as the staple fiber B, and the staple fiber C1 in Example 1 was used as the staple fiber C1 in the nonwoven fabric layer α, and the mass contents were changed to 32 mass%, 56 mass%, and 12 mass%, respectively. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 88 mass%, a mass ratio of staple fiber A to staple fiber B of 0.57, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption was obtained from the laminate with a thickness of 5 mm. The composition of the nonwoven fabric for sound absorption and the evaluation results are shown in Table 2.

[0080] <Example 8> The nonwoven fabric layer α was processed under the same steps and conditions as in Example 1, except that the staple fiber A in Example 1 was used as the staple fiber A in the nonwoven fabric layer α, the staple fiber B in Example 1 was used as the staple fiber B, and the staple fiber C1 in Example 1 was used as the staple fiber C1 in the nonwoven fabric layer α, and the mass contents were changed to 15 mass%, 80 mass%, and 5 mass%, respectively. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 95 mass%, a mass ratio of staple fiber A to staple fiber B of 0.19, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption was obtained from the laminate with a thickness of 5 mm. The composition of the nonwoven fabric for sound absorption and the evaluation results are shown in Table 2.

[0081] <Example 9> The nonwoven fabric layer α was processed under the same steps and conditions as in Example 1, except that the staple fiber A in Example 1 was used as the staple fiber A in the nonwoven fabric layer α, the staple fiber B in Example 1 was used as the staple fiber B, and the staple fiber C1 in Example 1 was used as the staple fiber C1 in the nonwoven fabric layer α, and the mass contents were changed to 50 mass%, 45 mass%, and 5 mass%, respectively. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 95 mass%, a mass ratio of the staple fiber A to the staple fiber B of 1.11, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption was obtained from the laminate with a thickness of 5 mm. The composition of the nonwoven fabric for sound absorption and the evaluation results are shown in Table 2.

[0082] <Example 10> The nonwoven fabric layer α was processed under the same steps and conditions as in Example 1, except that the staple fiber A in Example 1 was used as the staple fiber A in the nonwoven fabric layer α, the staple fiber B in Example 1 was used as the staple fiber B, and the staple fiber C1 in Example 1 was used as the staple fiber C1 in the nonwoven fabric layer α, and the mass contents were changed to 60 mass%, 35 mass%, and 5 mass%, respectively. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 95 mass%, a mass ratio of the staple fiber A to the staple fiber B of 1.71, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption was obtained from the laminate with a thickness of 5 mm. The composition of the nonwoven fabric for sound absorption and the evaluation results are shown in Table 2.

[0083] <Example 11> The nonwoven fabric layer α was processed under the same process and conditions as in Example 1, except that the staple fiber C1 in the nonwoven fabric layer α was changed to a core-sheath staple fiber (core-sheath ratio 1:1) having a fineness of 2.2 dtex, a core made of polyethylene terephthalate (PET) with a melting point of 255°C, and a sheath made of a crystalline copolymer polyester with a melting point of 140°C. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 95% by mass, a mass ratio of staple fiber A to staple fiber B of 0.58, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption was obtained from the laminate with a thickness of 5 mm. The composition of the nonwoven fabric for sound absorption and the evaluation results are shown in Table 2.

[0084] <Example 12> The nonwoven fabric layer α had a sheath-core staple fiber (core-sheath ratio 1:1) with a fineness of 2.2 dtex and a core made of polyethylene terephthalate (PET) with a melting point of 255°C and a sheath made of a crystalline copolymer polyester with a melting point of 150°C. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 95% by mass, a mass ratio of staple fiber A to staple fiber B of 0.58, and a basis weight of 300 g / m. 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption was obtained from the laminate with a thickness of 5 mm. The composition of the nonwoven fabric for sound absorption and the evaluation results are shown in Table 2.

[0085] <Example 13> The nonwoven fabric layer α was processed under the same process and conditions as in Example 1, except that the staple fiber C1 in the nonwoven fabric layer α was changed to a core-sheath staple fiber (core-sheath ratio 1:1) having a fineness of 2.2 dtex, a core made of polyethylene terephthalate (PET) with a melting point of 255°C, and a sheath made of a crystalline copolymer polyester with a melting point of 175°C. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 95% by mass, a mass ratio of staple fiber A to staple fiber B of 0.58, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the laminate with a thickness of 5 mm. The composition of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 3.

[0086] <Example 14> The nonwoven fabric layer α was processed under the same process and conditions as in Example 1, except that the staple fiber C1 in the nonwoven fabric layer α was changed to a core-sheath staple fiber (core-sheath ratio 1:1) having a fineness of 2.2 dtex, a core made of polyethylene terephthalate (PET) with a melting point of 255°C, and a sheath made of an amorphous copolymer polyester with a melting point of 160°C. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 95% by mass, a mass ratio of staple fiber A to staple fiber B of 0.58, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the laminate with a thickness of 5 mm. The composition of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 3.

[0087] <Example 15> The nonwoven fabric layer β was made of polyethylene terephthalate (PET) staple fibers having a fineness of 6.6 dtex and a melting point of 255°C, and the staple fibers C2 of Example 1 were used as the staple fibers of the nonwoven fabric layer β, and the staple fibers C2 of Example 1 were used as the staple fibers C2, and the mass contents were changed to 60% by mass and 40% by mass, respectively. Processing was performed under the same steps and conditions as in Example 1. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 95% by mass, a mass ratio of staple fiber A to staple fiber B of 0.58, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the laminate with a thickness of 5 mm. The composition of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 3.

[0088] <Example 16> The nonwoven fabric layer β was made of polyethylene terephthalate (PET) staple fibers having a fineness of 6.6 dtex and a melting point of 255°C. The staple fibers C2 of Example 1 were used as the staple fibers of the nonwoven fabric layer β, and the staple fibers C2 of Example 1 were used as the staple fibers C2. The mass contents of the staple fibers A and B of the nonwoven fabric layer α were 95 mass%, the mass ratio of the staple fibers A and B was 0.58, and the basis weight was 300 g / m. 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the laminate with a thickness of 5 mm. The composition of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 3.

[0089] <Example 17> The weight of the nonwoven fabric layer α is 250 g / m 2 The nonwoven fabric layer α had a mass content of staple fiber A and staple fiber B of 95 mass%, a mass ratio of staple fiber A to staple fiber B of 0.58, and a basis weight of 250 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the laminate with a thickness of 5 mm. The composition of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 3.

[0090] <Example 18> The weight of the nonwoven fabric layer α is 200 g / m 2 The nonwoven fabric layer α had a mass content of staple fiber A and staple fiber B of 95 mass%, a mass ratio of staple fiber A to staple fiber B of 0.58, and a basis weight of 200 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the laminate with a thickness of 5 mm. The composition of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 3.

[0091] [Table 1]

[0092] [Table 2]

[0093] [Table 3]

[0094] The nonwoven fabrics for sound absorption materials of Examples 1 to 18 had high tensile elongation at break of the nonwoven fabric layer β and excellent conformability, and the nonwoven fabrics for sound absorption materials had low static friction coefficients and excellent smoothness. In addition, the thickness after pressing was relatively large, excellent thickness recovery during molding, and the amount of fiber loss during cutting was small, which was good. Furthermore, the laminated nonwoven fabrics for sound absorption materials had high low-frequency sound absorption coefficients and high-frequency sound absorption coefficients.

[0095] The nonwoven fabric laminate for sound absorbing material of the Example had high tensile elongation at break and excellent conformability of the nonwoven fabric layer β due to the effect of the content of short fiber C2, and the nonwoven fabric for sound absorbing material had a low static friction coefficient and excellent smoothness, compared with the nonwoven fabric laminate for sound absorbing material of Comparative Example 10. In addition, the thickness after pressing was large, and the thickness recovery during molding was excellent compared with Comparative Example 3 due to the effect of short fiber B, compared with Comparative Example 4 due to the effect of short fiber C1, compared with Comparative Example 7 due to the effect of the content mass ratio of short fiber A and short fiber B, and compared with Comparative Example 8 due to the effect of the melting point of the sheath of short fiber C1.

[0096] Regarding the amount of fiber loss during cutting, in comparison with Comparative Example 5, the amount of fiber loss was low and good due to the effect of the content of short fiber C1, and in comparison with Comparative Example 9, the amount of fiber loss was low and good due to the effect of the melting point of the sheath of short fiber C1.

[0097] Furthermore, in comparison with Comparative Examples 1, 2, 3, 6 and 7, due to the effects of the fineness, blending amount and blending ratio of short fiber A and short fiber B, and in comparison with Comparative Examples 4 and 8, due to the effects of the content of short fiber C1 and the melting point of the sheath, the low frequency sound absorption coefficient of the laminated nonwoven fabric for sound absorbing material was high, and the high frequency sound absorption coefficient was high. Comparative Examples are shown below.

[0098] <Comparative Example 1> The nonwoven fabric layer α was processed under the same process and conditions as in Example 1, except that the staple fiber A in the nonwoven fabric layer α was changed to a polyethylene terephthalate (PET) staple fiber having a fineness of 0.3 dtex and a melting point of 255°C. The content of staple fiber A and staple fiber B in the nonwoven fabric layer α was 95% by mass, the content ratio of staple fiber A to staple fiber B was 0.58, and the basis weight was 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the laminate with a thickness of 5 mm. The composition of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 4.

[0099] The nonwoven fabric for sound absorption material of Comparative Example 1 had a high tensile elongation at break of the nonwoven fabric layer β and excellent conformability, and the static friction coefficient of the nonwoven fabric for sound absorption material was low and excellent smoothness. In addition, the thickness after pressing was large, the thickness recovery during molding was excellent, and the amount of fiber loss during cutting was small, which was good. However, the low-frequency sound absorption coefficient and the high-frequency sound absorption coefficient of the laminated nonwoven fabric for sound absorption material were low.

[0100] <Comparative Example 2> The nonwoven fabric layer α contained 95 mass% polyethylene terephthalate (PET) staple fibers having a fineness of 4.4 dtex and a melting point of 255°C as staple fibers B, and 5 mass% of the staple fibers C1 of Example 1 as staple fibers C1. No staple fibers A were used. Processing was performed under the same steps and conditions as in Example 1. The nonwoven fabric layer α contained 95 mass% of staple fibers A and B, and had a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the laminated nonwoven fabric having a thickness of 5 mm. The configuration of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 4. The nonwoven fabric for sound absorption material of Comparative Example 2 had a low sound absorption coefficient at low frequencies and a low sound absorption coefficient at high frequencies.

[0101] <Comparative Example 3> The nonwoven fabric layer α contained 95 mass% polyethylene terephthalate (PET) staple fibers having a fineness of 3.6 dtex and a melting point of 255°C as staple fibers A, 5 mass% of the staple fibers C1 of Example 1 as staple fibers C1, and no staple fibers B. The nonwoven fabric layer α contained 95 mass% of staple fibers A and B, and had a basis weight of 300 g / m 2, thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the nonwoven fabric having a thickness of 5 mm. The configuration of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 4. The nonwoven fabric for sound absorption material of Comparative Example 3 had a small thickness after pressing and was poor in thickness recovery during molding, and the laminated nonwoven fabric for sound absorption material had low low-frequency sound absorption coefficient and low high-frequency sound absorption coefficient.

[0102] <Comparative Example 4> The nonwoven fabric layer α was processed under the same steps and conditions as in Example 1, except that the staple fiber A in Example 1 was used as the staple fiber A in the nonwoven fabric layer α, the staple fiber B in Example 1 was used as the staple fiber B, and the staple fiber C1 in Example 1 was used as the staple fiber C1 in the nonwoven fabric layer α, and the mass contents were changed to 30 mass%, 55 mass%, and 15 mass%, respectively. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 85 mass%, a mass ratio of staple fiber A to staple fiber B of 0.55, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the nonwoven fabric having a thickness of 5 mm. The configuration of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 4. The nonwoven fabric for sound absorption material of Comparative Example 4 had a small thickness after pressing and was poor in thickness recovery during molding, and the laminated nonwoven fabric for sound absorption material had low low-frequency sound absorption coefficient and low high-frequency sound absorption coefficient.

[0103] <Comparative Example 5> The nonwoven fabric layer α was processed under the same steps and conditions as in Example 1, except that the staple fiber A in Example 1 was used as the staple fiber A in the nonwoven fabric layer α, the staple fiber B in Example 1 was used as the staple fiber B, and the staple fiber C1 in Example 1 was used as the staple fiber C1 in the nonwoven fabric layer α, and the mass contents were changed to 37 mass%, 62 mass%, and 1 mass%, respectively. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 99 mass%, a mass ratio of staple fiber A to staple fiber B of 0.60, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the laminate having a thickness of 5 mm. The configuration and evaluation results of the nonwoven fabric for sound absorption material are shown in Table 4. The nonwoven fabric for sound absorption material of Comparative Example 5 was inferior in that a large amount of fibers fell off when cut.

[0104] <Comparative Example 6> The nonwoven fabric layer α was processed under the same steps and conditions as in Example 1, except that the staple fiber A in Example 1 was used as the staple fiber A in the nonwoven fabric layer α, the staple fiber B in Example 1 was used as the staple fiber B, and the staple fiber C1 in Example 1 was used as the staple fiber C1 in the nonwoven fabric layer α, and the mass contents were changed to 4 mass%, 91 mass%, and 5 mass%, respectively. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 95 mass%, a mass ratio of staple fiber A to staple fiber B of 0.04, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the laminated nonwoven fabric of Comparative Example 6 with a thickness of 5 mm. The configuration of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 4. The nonwoven fabric for sound absorption material of Comparative Example 6 had a low sound absorption coefficient at low frequencies and a low sound absorption coefficient at high frequencies.

[0105] <Comparative Example 7> The nonwoven fabric layer α was processed under the same steps and conditions as in Example 1, except that the staple fiber A in Example 1 was used as the staple fiber A in the nonwoven fabric layer α, the staple fiber B in Example 1 was used as the staple fiber B, and the staple fiber C1 in Example 1 was used as the staple fiber C1 in the nonwoven fabric layer α, and the mass contents were changed to 76 mass%, 19 mass%, and 5 mass%, respectively. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 95 mass%, a mass ratio of staple fiber A to staple fiber B of 4.00, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the nonwoven fabric having a thickness of 5 mm. The configuration of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 5. The nonwoven fabric for sound absorption material of Comparative Example 7 had a small thickness after pressing and was poor in thickness recovery during molding, and the laminated nonwoven fabric for sound absorption material had low low-frequency sound absorption coefficient and low high-frequency sound absorption coefficient.

[0106] <Comparative Example 8> The nonwoven fabric layer α was processed under the same process and conditions as in Example 1, except that the staple fiber C1 in the nonwoven fabric layer α was changed to a core-sheath staple fiber (core-sheath ratio 1:1) having a fineness of 2.2 dtex, a core made of polyethylene terephthalate (PET) with a melting point of 255°C, and a sheath made of a crystalline copolymer polyester with a melting point of 130°C. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 95% by mass, a mass ratio of staple fiber A to staple fiber B of 0.58, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2A nonwoven fabric laminate for sound absorption material was obtained from the nonwoven fabric having a thickness of 5 mm. The configuration of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 5. The nonwoven fabric for sound absorption material of Comparative Example 8 had a small thickness after pressing and was poor in thickness recovery during molding, and the laminated nonwoven fabric for sound absorption material had low low-frequency sound absorption coefficient and low high-frequency sound absorption coefficient.

[0107] <Comparative Example 9> The nonwoven fabric layer α was processed under the same process and conditions as in Example 1, except that the staple fiber C1 in the nonwoven fabric layer α was changed to a core-sheath staple fiber (core-sheath ratio 1:1) having a fineness of 2.2 dtex, a core made of polyethylene terephthalate (PET) with a melting point of 255°C, and a sheath made of a crystalline copolymer polyester with a melting point of 195°C. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 95% by mass, a mass ratio of staple fiber A to staple fiber B of 0.58, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the laminate having a thickness of 5 mm. The configuration of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 5. The nonwoven fabric for sound absorption material of Comparative Example 9 was inferior in that a large amount of fibers fell off when cut.

[0108] <Comparative Example 10> The nonwoven fabric layer β was made of polyethylene terephthalate (PET) staple fibers having a fineness of 6.6 dtex and a melting point of 255°C. The staple fibers C2 of Example 1 were used as the staple fibers of the nonwoven fabric layer β, and the staple fibers C2 of Example 1 were used as the staple fibers C2, and the mass contents were changed to 82% by mass and 18% by mass, respectively. Processing was performed under the same steps and conditions as in Example 1. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 95% by mass, a mass ratio of staple fiber A to staple fiber B of 0.58, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the nonwoven fabric having a thickness of 5 mm. The configuration of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 5. The nonwoven fabric for sound absorption material of Comparative Example 10 had a high static friction coefficient and was poor in smoothness.

[0109] <Comparative Example 11> The nonwoven fabric layer β was made of polyethylene terephthalate (PET) staple fibers having a fineness of 6.6 dtex and a melting point of 255°C. The staple fibers C2 of Example 1 were used as the staple fibers of the nonwoven fabric layer β, and the staple fibers C2 of Example 1 were used as the staple fibers C2, and the mass contents were changed to 35% by mass and 65% by mass, respectively. Processing was performed under the same steps and conditions as in Example 1. The nonwoven fabric layer α had a staple fiber A and staple fiber B content of 95% by mass, a mass ratio of staple fiber A to staple fiber B of 0.58, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2 A nonwoven fabric laminate for sound absorption material was obtained from the nonwoven fabric layer β having a thickness of 5 mm. The configuration of the nonwoven fabric for sound absorption material and the evaluation results are shown in Table 5. The nonwoven fabric for sound absorption material of Comparative Example 11 had a low tensile elongation at break of the nonwoven fabric layer β and was poor in conformity.

[0110] <Comparative Example 12> The nonwoven fabric for sound absorption was processed under the same steps and conditions as in Example 1, except that the nonwoven fabric layer β was not used and the nonwoven fabric for sound absorption was composed only of the nonwoven fabric layer α. The nonwoven fabric layer α contained 95% by mass of short fiber A and short fiber B, had a mass ratio of 0.58 to short fiber A and short fiber B, and had a basis weight of 300 g / m 2 A nonwoven fabric for sound absorption with a thickness of 25 mm was obtained. The composition and evaluation results of the nonwoven fabric for sound absorption are shown in Table 5.

[0111] The nonwoven fabric for sound absorption material of Comparative Example 12 did not use the nonwoven fabric layer β, so it had a high static friction coefficient and poor smoothness, and part of the nonwoven fabric was scraped or torn due to friction with the metal platen during the pressing process. The thickness after pressing was large, the thickness recovery during molding was excellent, and the amount of fiber loss during cutting was small, so it was good, but the low-frequency sound absorption coefficient and high-frequency sound absorption coefficient of the laminated nonwoven fabric for sound absorption material were low.

[0112] <Comparative Example 13> The nonwoven fabric layer β was processed under the same process and conditions as in Example 1, except that the short fiber C2 was not used and the polyethylene terephthalate (PET) short fiber having a fineness of 6.6 dtex and a melting point of 255°C was used at 100% by mass. The nonwoven fabric layer α had a short fiber A and short fiber B content of 95% by mass, a short fiber A to short fiber B content ratio of 0.58, and a basis weight of 300 g / m 2 , thickness 25 mm, and the weight of the nonwoven fabric layer β is 60 g / m 2A nonwoven fabric for sound absorption was obtained from the nonwoven fabric having a thickness of 5 mm. The nonwoven fabric layer α and the nonwoven fabric layer β were not partially fused. The composition of the nonwoven fabric for sound absorption and the evaluation results are shown in Table 5.

[0113] In the nonwoven fabric for sound absorption material of Comparative Example 13, since the short fiber C2 was not used, the nonwoven fabric layer α and the nonwoven fabric layer β were not integrated in the thermal bonding process, and a nonwoven fabric laminate for sound absorption material could not be obtained. In the press processing, the nonwoven fabric layer α and the nonwoven fabric layer β were separated without being integrated, and further wrinkles were generated on the surface of the nonwoven fabric, resulting in a product of significantly inferior quality, and therefore it was not possible to measure the normal incidence sound absorption coefficient.

[0114] [Table 4]

[0115] [Table 5] [Industrial Applicability]

[0116] The nonwoven fabric for sound absorbing material of the present invention has excellent thickness recovery and conformability during molding, and has excellent sound absorbing performance, and is therefore particularly suitable for use as a sound absorbing material for automobiles, etc.

Claims

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

2. 2. The nonwoven fabric laminate for sound absorbing materials according to claim 1, wherein the staple fibers C1 are core-sheath type composite staple fibers, and the resin constituting the sheath portion is a thermoplastic resin having a melting point of 135 to 190°C.

3. 3. The nonwoven fabric laminate for sound absorbing materials according to claim 1, wherein the staple fibers C1 have a fineness of 1.0 to 5.0 dtex.

4. 4. The nonwoven fabric laminate for sound absorbing materials according to claim 1, wherein the thermoplastic resin having a melting point of 135 to 190° C. is a crystalline resin.

5. The nonwoven fabric laminate for sound absorbing materials according to any one of claims 1 to 4, wherein the staple fibers C2 are core-sheath type composite staple fibers, and a resin constituting the sheath portion is a thermoplastic resin having a melting point of 70 to 190°C.

6. 6. The nonwoven fabric laminate for sound-absorbing materials according to claim 1, wherein the thermoplastic resin having a melting point of 70 to 190° C. is a noncrystalline resin.

7. The nonwoven fabric layer α has a basis weight of 100 g / m ２ More than 700g / m ２ The nonwoven fabric laminate for sound absorbing materials according to any one of claims 1 to 6, wherein the thickness of the nonwoven fabric layer α is 7 mm or more and 40 mm or less.

8. The nonwoven fabric layer β has a basis weight of 30 g / m ２ 120g / m or more ２ The nonwoven fabric laminate for sound absorbing materials according to any one of claims 1 to 7, wherein:

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

10. The nonwoven fabric laminate for sound absorbing materials according to any one of claims 1 to 9, wherein the staple fiber A, the staple fiber B, the staple fiber C1 and the staple fiber C2 are all polyester-based staple fibers.

11. The nonwoven fabric laminate for sound absorbing material according to any one of claims 1 to 10 is used as a substrate, and the air permeability is 3 to 50 cm ３ / cm ２ The sound-absorbing material further comprises a surface nonwoven fabric layer γ of the nonwoven fabric laminate for sound-absorbing material.

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