JP2022028195A - Nonwoven fabric for sound absorbing material, sound absorbing material, and manufacturing method of nonwoven fabric - Google Patents

Abstract

To provide a nonwoven fabric for a sound absorbing material excellent in sound absorbing performance in low and high frequency areas, and excellent in productivity and quality, and to provide a manufacturing method of the sound absorbing material and the nonwoven fabric.SOLUTION: A nonwoven fabric for a sound absorbing material contains 30 to 80 mass% of a staple fiber A having a fineness of 0.4 to 0.9 dtex and 2 mass% or more of a staple fiber B having a fineness of 0.0005-0.3 dtex, and a transmission coefficient of the staple fiber A represented by the following expression (1) is in a range of 15 to 260: transmission coefficient=(fineness×strength×√elongation×√number of crimps×√degree of crimp)/(fiber length)--(1), where the fineness is expressed by dtex, the strength is expressed by cN/dtex, the elongation is expressed by %, the number of crimps is expressed by the number of ridges/25 mm, the degree of crimp is expressed by %, and the fiber length is expressed by cm.SELECTED DRAWING: None

Description

The present invention relates to a non-woven fabric for a sound absorbing material, a sound absorbing material, and a method for manufacturing a non-woven fabric for a sound absorbing material.

In recent years, quietness has become more important than ever as one of the commercial values of products in automobiles and electric products. Generally, it is effective to increase the mass and thickness of the sound absorbing material, which is a countermeasure component, as a noise countermeasure. It is required to be compact and compact.

In Patent Document 1, one side of a sheet-like base material containing ultrafine fibers having a fineness of 0.1 to 1.0 dtex and short fibers having a fineness of 1.2 to 5.0 dtex is heated and pressed to adjust air permeability. A method for manufacturing a soundproof material for a vehicle having a film formed has been proposed.

Further, Patent Document 2 proposes a mixed fiber non-woven fabric for a face mask containing synthetic fibers having a fineness of 0.4 to 0.8 dtex and cellulose fibers as main components.

Further, Patent Document 3 proposes a sound absorbing material constituent member containing ultrafine fibers having a single fiber fineness of 0.0001 to 1.0 dtex.

Japanese Unexamined Patent Publication No. 2016-34828 International Publication No. 2020/31798 Japanese Unexamined Patent Publication No. 2004-354844

According to the findings of the present inventors, since the soundproofing material for vehicles disclosed in Patent Document 1 contains ultrafine fibers, the soundproofing performance tends to be relatively excellent.

However, the non-woven fabric for a sound absorbing material or the like is obtained through a step (hereinafter referred to as a card step) in which fibers containing ultrafine fibers are subjected to a fiber opening treatment by a card machine or a fleece machine in these manufacturing steps. In the above-mentioned card process, the ultrafine fibers tend to have thread breakage and wrapping around the needle cloth as compared with the fibers having a relatively large fineness. From the above, there is a problem that the non-woven fabric for sound absorbing material using ultrafine fibers is inferior in productivity. In addition, there is also a tendency for ultrafine fibers that are cut inside the non-woven fabric for sound absorbing material to be generated as fiber lumps. There is a problem that the quality of the above-mentioned sound absorbing material is also inferior.

Regarding the above-mentioned productivity problem, Patent Document 2 states that by setting the physical properties of the ultrafine fibers used for the non-woven fabric within a specific range, it is possible to suppress thread breakage and wrapping around the needle cloth in the card process. However, Patent Document 2 does not disclose the relationship between the degree of crimping of ultrafine fibers and productivity, and there is a problem that the productivity when producing a nonwoven fabric for sound absorbing material is inferior. Further, there is a tendency that ultrafine fibers are generated as fiber lumps, and in this case, there is a problem that the sound absorbing performance as a sound absorbing material is inferior and the quality is also inferior.

On the other hand, Patent Document 3 discloses that ultrafine fibers are used as fibers constituting the sound absorbing material constituent member in order to obtain an excellent sound absorbing effect in a low frequency region of 500 Hz or less. However, the above-mentioned ultrafine fiber is a method for obtaining ultrafine fiber by desealing the sea component of a non-woven fabric made of sea-island fiber, and has a problem of being inferior in productivity. Further, there is a disclosure of a method in which only split-type composite fibers are melt-spun and deposited to form a web, and further divided by a water stream to obtain ultrafine fibers. However, in the method of depositing melt-spun filaments, the filaments are fused to each other. There is a problem that the split type composite fiber is difficult to split and the sound absorption performance is substantially inferior.

Therefore, in view of the above circumstances, the present invention comprises a non-woven fabric for a sound absorbing material for obtaining a sound absorbing material having excellent sound absorbing performance and productivity in a low frequency region and a high frequency region and also having excellent quality, and the above sound absorbing material. An object of the present invention is to provide a sound absorbing material or the like using a non-woven fabric for use.

In order to solve the above problems, the present invention has the following configurations. That is,
(1) The staple fiber A containing 30 to 80% by mass of the staple fiber A having a fineness of 0.4 to 0.9 dtex and 2% by mass or more of the staple fiber B having a fineness of 0.0005 to 0.3 dtex. The non-woven fabric for sound absorbing material has a passing coefficient in the range of 15 to 260 shown in the following formula (1).
Passing coefficient = (fineness x strength x √ elongation x √ number of crimps x √ crimp degree) / (fiber length) (1)
<Fineness (dtex), strength (cN / dtex), elongation (%), number of crimps (mountain / 25 mm), crimp degree (%), fiber length (cm)>
(2) The nonwoven fabric for sound absorbing material according to (1), wherein the basis weight is 150 g / m ² or more and 500 g / m ² or less, and the thickness is 0.6 mm or more and 4.0 mm or less.
(3) The nonwoven fabric for sound absorbing material according to (1) or (2), which has a density of 0.07 g / cm ³ or more and 0.40 g / cm ³ or less.
(4) The nonwoven fabric for a sound absorbing material according to any one of (1) to (3), wherein the staple fiber A is a polyester-based staple fiber.
(5) The sound absorption according to any one of (1) to (4), wherein the staple fiber A has a tensile strength of 5 cN / dtex or more and the staple fiber A has a tensile elongation of 20 to 35%. Non-woven fabric for materials.
(6) The nonwoven fabric for a sound absorbing material according to any one of (1) to (5) and a layered material composed of a fibrous porous body layer, a foam layer, or an air layer, and the layered material has. , A sound absorbing material laminated on one surface of the non-woven fabric for sound absorbing material, and the thickness of the layered material is 5 to 50 mm.
(7) A step of subjecting the short fiber A and the split type composite fiber to a fiber opening treatment to obtain a mixed fiber web of the short fiber A and the split type composite fiber, and the mixed fiber web using a water jet punch nozzle three times. It has a step of dividing the short fiber B from the split type composite fiber after passing through the above, and the fineness of the short fiber A is 0.4 to 0.9 dtex, and the following formula (1) of the short fiber A is provided. ) Is in the range of 15 to 260, the fineness of the short fiber B is 0.0005 to 0.3 dtex, and the content of the short fiber A is 30 with respect to the entire mixed fiber web. It is a method for producing a non-woven fabric for a sound absorbing material, which is ~ 80% by mass, and the content of the split type composite fiber is 20 to 70% by mass with respect to the entire mixed fiber web.

Passing coefficient = (fineness x strength x √ elongation x √ number of crimps x √ crimp degree) / (fiber length) (1)
<Fineness (dtex), strength (cN / dtex), elongation (%), number of crimps (mountain / 25 mm), crimp degree (%), fiber length (cm)>

According to the present invention, by using an ultrafine fiber having predetermined physical properties, it is used as a sound absorbing material for obtaining a sound absorbing material having excellent sound absorbing performance and productivity in the low frequency region and high frequency region and also having excellent quality. Non-woven fabrics can be provided.

Hereinafter, embodiments of the present invention will be described in detail.

The nonwoven fabric for sound absorbing material of the present invention contains 30 to 80% by mass of staple fibers A having a fineness of 0.4 to 0.9 dtex, and further contains 2% by mass of staple fibers B having a fineness of 0.0005 to 0.3 dtex. With the above content, the passage coefficient of the staple fiber A shown in the following formula (1) is in the range of 15 to 260.
Passing coefficient = (fineness x strength x √ elongation x √ number of crimps x √ crimp degree) / (fiber length) (1)
<Fineness (dtex), strength (cN / dtex), elongation (%), number of crimps (mountain / 25 mm), crimp degree (%), fiber length (cm)>
Such a non-woven fabric for sound absorbing material (hereinafter, may be simply referred to as "nonwoven fabric") is a thread breakage of the short fiber A or wrapping of the short fiber A around the staple cloth in the card process by a card machine or the like in the manufacturing process. Is suppressed. By suppressing the occurrence of thread breakage of the short fiber A and wrapping of the short fiber A around the staple cloth, the productivity of the non-woven fabric for sound absorbing material becomes excellent, and the non-woven fabric for sound absorbing material is cut inside. Since the generation of the staple fibers A as fiber lumps is also suppressed, high sound absorption performance can be obtained in both the low frequency region and the high frequency region. Further, since the short fibers A cut inside the non-woven fabric for sound absorbing material are suppressed from being generated as fiber lumps, the present inventor can obtain the effect that the quality of the non-woven fabric for sound absorbing material is also excellent. I found it. In addition, these effects may be collectively referred to as "effects of the present invention". It is presumed that the non-woven fabric for sound absorbing material of the present invention can exert the above effect because the passage coefficient of the staple fiber A is in the range of 15 to 260.

The nonwoven fabric for sound absorbing material of the present invention has a feature (feature point 1) that it contains 2 or more of short fibers B having a fineness of 0.0005 to 0.3 dtex with respect to the total mass of the nonwoven fabric for sound absorbing material. In the configuration of the nonwoven fabric for sound absorbing material of the present invention, the effect of the present invention can be obtained when the nonwoven fabric for sound absorbing material satisfies the above-mentioned feature 1. Since the staple fiber B is a fiber having a fineness in the above range, a porous portion having a large number of fine pores can be formed inside the non-woven fabric for sound absorbing material, and the sound absorbing performance of the sound absorbing material using this non-woven fabric can be improved. It will be excellent. By setting the fineness of the staple fibers B to 0.0005 dtex or more, it is possible to prevent the staple fibers B from being densely packed in a bundle, and to form a porous portion inside the non-woven fabric for sound absorbing material at a constant ratio. , The sound absorbing performance of the non-woven fabric for sound absorbing material is excellent. Further, by setting the fineness of the short fiber B to 0.3 dtex or less, the above-mentioned porous portion becomes fine, and as a result, when sound passes through the voids (that is, the porous portion) between the fibers. Sound can be efficiently converted into heat by air friction with fibers around the voids, and excellent sound absorption can be obtained when used as a sound absorbing material. In the above points, the fineness of the staple fiber B is preferably 0.01 to 0.25 dtex, and more preferably 0.05 to 0.2 dtex.

Further, the staple fiber B preferably has a component constituting the split type composite fiber peeled off or separated from the split type composite fiber. Here, the split type composite fiber is a fiber that can be split into a plurality of components by an external force applied to the fiber by a mechanical entanglement treatment method such as a needle punch method or a water jet punch method or a heat shrinkage force of a constituent component. Point to. Further, in the split type composite fiber, at least one of the constituent components is divided into two or more in the fiber cross section, at least a part of the constituent components is exposed on the fiber surface, and the exposed portion is in the length direction of the fiber. It is preferable that the fiber has a fiber cross-sectional structure continuously formed in the fiber. Since the precursor of the short fiber B is the above-mentioned split type composite fiber, the split type composite fiber maintains a relatively thick fineness in the card process, the short fiber A is uniformly dispersed inside the non-woven fabric, and the sound absorbing material is used. The generation of short fibers A as fiber lumps is suppressed inside the nonwoven fabric for sound absorbing material, and the quality of the nonwoven fabric for sound absorbing material is improved. Further, by uniformly dispersing the short fibers A, a porous portion having a large number of fine pores can be formed inside the non-woven fabric for sound absorbing material, and the sound absorbing performance when this non-woven fabric is used as the sound absorbing material is excellent. Will be. Further, it is possible to suppress the thread breakage of the short fiber A in the card process and the wrapping around the staple cloth, and as a result, the productivity of the non-woven fabric for the sound absorbing material can be improved. In the above points, the fineness of the split type composite fiber is preferably 1.1 to 20.0 dtex. By setting the fineness of the split type composite fiber to 1.1 dtex or more, the staple fibers A are uniformly dispersed as described above, and excellent sound absorption and productivity can be obtained. On the other hand, by setting the fineness of the split type composite fiber to 20.0 dtex or less, the energy for obtaining the staple fiber B can be reduced by mechanical treatment, and the productivity can be increased. In the above points, the fineness of the split type composite fiber is preferably 1.3 to 18.0 dtex, more preferably 1.4 to 15.0 dtex.

Further, by containing 2% by mass or more of the short fibers B with respect to the total mass of the non-woven fabric for sound absorbing material, the porous portion formed in a certain ratio inside the non-woven fabric for sound absorbing material becomes fine, and the sound absorbing material becomes fine. Excellent sound absorption can be obtained when used as a non-woven fabric. Further, when the precursor of the short fiber B is a split type composite fiber, the frequency of thread breakage, wrapping around the staple cloth, and fiber lumps generated in the entire non-woven fabric for sound absorbing material is reduced in the carding process. As a result, it is presumed that a non-woven fabric for a sound absorbing material having excellent productivity and quality can be obtained. On the other hand, if the content of the short fibers B constituting the non-woven fabric for sound absorbing material is too large, even if the precursor of the short fibers B is a split type composite fiber, it is generated in the entire non-woven fabric for sound absorbing material in the card process. There is a tendency for thread breakage, wrapping around staple cloth, and fiber lumps to occur. Therefore, the content of the staple fibers B is preferably 70% by mass or less with respect to the total mass of the non-woven fabric for sound absorbing material. Further, from the above point, the content of the staple fiber B is preferably 4% by mass or more, more preferably 6% by mass or more, based on the total mass of the nonwoven fabric for sound absorbing material. Further, it is preferably 50% by mass or less, and more preferably 35% by mass or less.

Next, the non-woven fabric for a sound absorbing material of the present invention contains 30 to 80% by mass of staple fibers A having a fineness of 0.4 to 0.9 dtex, and the short fibers A pass through the following formula (1). It has a feature (feature point 2) that the coefficient is in the range of 15 to 260.

Passing coefficient = (fineness x strength x √ elongation x √ number of crimps x √ crimp degree) / (fiber length) (1)
<Fineness (dtex), strength (cN / dtex), elongation (%), number of crimps (mountain / 25 mm), crimp degree (%), fiber length (cm)>
When the nonwoven fabric for sound absorbing material of the present invention satisfies the above-mentioned feature point 2, the effect of the present invention can be obtained. As described above, the short fiber A having a low fineness tends to cause thread breakage in the card process, wrap around the staple cloth, and easily form a fiber lump inside the non-woven fabric for sound absorbing material. However, even if the staple fiber A has a fineness of 0.4 to 0.9 dtex, if the passage coefficient is within the range of 15 to 260, the occurrence of yarn breakage of the staple fiber A in the carding process is suppressed. To. That is, the non-woven fabric for a sound absorbing material containing the staple fiber A at a specific content has a fineness of 0.4 to 0.9 dtex and a passage coefficient of 15 to 260. The occurrence of thread breakage of the staple fiber A in the card process is suppressed, the non-woven fabric for sound absorbing material is excellent in productivity, and the sound absorbing performance of the sound absorbing material using the non-woven fabric for sound absorbing material is excellent. The mechanism is presumed to be as follows. By optimizing the balance between the fineness, strength, elongation, number of crimps, and crimping degree, which are the characteristics of the short fiber A, and the fiber length (that is, the passage coefficient of the short fiber A is 15 to 260). , Thread breakage due to friction between the short fiber A and the needle cloth in the card process is suppressed (this is considered to be particularly affected by the strength of the short fiber A and the elongation of the short fiber A). It is presumed that the wrapping of the short fiber A around the needle cloth in the card process is reduced (this is considered to be particularly affected by the fiber length of the short fiber A). Then, in the card process, the short fibers A and the short fibers B are uniformly dispersed and entangled inside the non-woven fabric, and the generation of the short fibers A as a fiber mass is suppressed inside the non-woven fabric for sound absorbing material (this). This is considered to be particularly affected by the number of crimps and the degree of crimp of the short fiber A), the quality of the non-woven fabric for sound absorbing material is improved, and the short fiber A is uniformly dispersed inside the non-woven fabric. A porous portion having a large number of fine pores can be formed inside the non-woven fabric for sound absorbing material, and the sound absorbing performance of the sound absorbing material using this non-woven fabric becomes excellent.

Further, the passage coefficient of the staple fiber A can be made desired by adjusting the fineness, strength, elongation, number of crimps, crimp degree and fiber length of the staple fiber A in consideration of all of them. For the above reasons, the passage coefficient of the staple fiber A is preferably 20 or more, and more preferably 150 or less. Further, it is more preferably 25 or more, and more preferably 100 or less.

The range that each of the fineness, strength, elongation, number of crimps, crimping degree and fiber length of the staple fiber A can be taken is particularly limited as long as the above-mentioned passing coefficient is in the range of 15 to 260. However, the preferred range for each of these is as follows.

The fineness of the staple fiber A is 0.4 to 0.9 dtex. By setting the fineness of the short fiber A to 0.9 dtex or less, the short fiber A having a low fineness can form a porous portion having a large number of fine pores inside the non-woven fabric for sound absorbing material. As a result, when sound passes through the voids (that is, the porous portion) between the fibers, the sound can be efficiently converted into heat by air friction with the fibers around the voids, and when used as a sound absorbing material. Excellent sound absorption can be obtained.

On the other hand, by setting the fineness of the short fibers A to 0.4 dtex or more, the short fibers A are uniformly dispersed inside the non-woven fabric in the card process, and the short fibers A are generated as fiber lumps inside the non-woven fabric for sound absorbing material. Therefore, the quality of the non-woven fabric for sound absorbing material is improved. Further, since the short fibers A are uniformly dispersed inside the nonwoven fabric, a porous portion having many fine pores can be formed inside the nonwoven fabric for sound absorbing material, and the sound absorbing performance when used as a sound absorbing material is excellent. Will be. In the above points, the fineness of the staple fiber A is preferably 0.5 to 0.8 dtex, and more preferably 0.5 to 0.7 dtex. In addition, in order to obtain ultrafine fibers having a fineness smaller than 0.4 to 0.9 dtex, it is necessary to adopt a method of desealing sea island fibers or an electrospinning method, but these methods produce short fibers and the like. There is a problem that the productivity is inferior to that of the melt spinning method and the wet spinning method. The staple fiber A used in the nonwoven fabric for sound absorbing material of the present invention has a fineness of 0.4 to 0.9 dtex. Therefore, the staple fibers A can be produced by a melt spinning method or a wet spinning method. That is, it is not necessary to use the method of desealing the sea island fibers or the electrospinning method to obtain the nonwoven fabric for sound absorbing material of the present invention. Therefore, the productivity of the non-woven fabric for sound-absorbing material of the present invention is superior to the productivity of the non-woven fabric for sound-absorbing material, which requires the use of a method for removing sea island fibers or an electrospinning method in the manufacturing process.

The tensile strength of the staple fiber A (sometimes referred to simply as "strength" in the present specification and the like) is preferably 2.5 cN / dtex or more. By setting the tensile strength of the short fiber A to 2.5 cN / dtex or more, the yarn breakage due to the friction between the short fiber A and the staple cloth in the card process in the manufacturing process of the non-woven fabric for sound absorbing material is further suppressed, and as a result. , The productivity of the non-woven fabric for sound absorbing material can be further improved. In the above points, the tensile strength of the staple fibers is more preferably 2.8 cN / dtex or more.

The tensile elongation of the staple fiber A (in the present specification and the like, it may be simply referred to as “elongation”) is preferably 20 to 40%. By setting the tensile elongation of the short fiber A to 20% or more, the yarn breakage due to the friction between the short fiber A and the staple cloth in the card process is further suppressed, and as a result, the productivity of the non-woven fabric for sound absorbing material is further improved. Can be made to. On the other hand, by setting the tensile elongation of the short fiber A to 40% or less, the wrapping around the staple cloth caused by the elongation of the short fiber A due to the friction with the staple cloth in the card process is further reduced, and as a result, sound absorption is achieved. The productivity of the non-woven fabric for materials can be further improved. In this respect, the tensile elongation of the staple fiber A is more preferably 22% to 35%.

The short fiber A has a tensile strength of 5 cN / dtex or more and a tensile elongation of 20 to 35%, which suppresses thread breakage due to friction between the short fiber A and the staple cloth in the card process and needles. It is preferable because the wrapping around the staple cloth, which is generated from the elongation of the short fibers A due to the friction with the cloth, can be further reduced, and the productivity of the non-woven fabric for sound absorbing material can be further improved. In addition, by suppressing thread breakage and wrapping around the staple cloth due to friction, the generation of fiber lumps is suppressed, and the short fibers A are uniformly dispersed to form a porous part having many fine pores as a non-woven fabric for sound absorbing material. As a result, the sound absorbing performance when this non-woven fabric is used as a sound absorbing material becomes excellent. Further, from the above point, the tensile strength of the staple fiber A is particularly preferably 6.0 cN / dtex or more.

The number of crimps of the staple fiber A is preferably 10.0 peaks / 25 mm or more. By setting the number of crimps of the short fiber A to 10.0 ridges / 25 mm or more, the short fiber A and the short fiber B are uniformly dispersed inside the non-woven fabric in the card process, and the short fiber A is formed inside the non-woven fabric for sound absorbing material. The generation of fibers A as fiber lumps is suppressed, and the quality of the non-woven fabric for sound absorbing material is improved. Further, by uniformly dispersing the short fibers A, a porous portion having many fine pores can be formed inside the non-woven fabric for sound absorbing material, and the sound absorbing performance of the sound absorbing material using this non-woven fabric is excellent. Become. In this respect, the number of crimps of the staple fiber A is more preferably 12.0 ridges / 25 mm or more, and particularly preferably 12.5 ridges / 25 mm or more. The upper limit of the number of crimps of the short fibers A is not particularly limited, but is preferably 18 threads / 25 mm or less from the viewpoint of dispersibility of the short fibers A.

The degree of crimping of the staple fibers A is preferably 12.0% or more. By setting the degree of crimp of the staple fiber A to 12.0%, the staple fiber A and the staple fiber B are uniformly dispersed in the card process, and the staple fiber A is generated as a fiber mass inside the non-woven fabric for sound absorbing material. This is suppressed, and the quality of the non-woven fabric for sound absorbing material is improved. Further, by uniformly dispersing the short fibers A, a porous portion having a large number of fine pores can be formed inside the non-woven fabric for a sound absorbing material, and the sound absorbing performance when used as a sound absorbing material becomes excellent. In the above points, the degree of crimping of the staple fiber A is more preferably 13.0% or more, and particularly preferably 14.0% or more. The upper limit of the degree of crimping of the staple fiber A is not particularly limited, but is preferably 19% or less from the viewpoint of dispersibility of the staple fiber A and the like.

The fiber length of the staple fiber A is preferably in the range of 2.5 to 4.5 cm. By setting the fiber length of the short fiber A to 4.5 cm or less, it is possible to suppress wrapping around the staple cloth in the card process in the manufacturing process of the non-woven fabric for sound absorbing material, and as a result, the productivity of the non-woven fabric for sound absorbing material is high. Can be improved. On the other hand, when the length is 2.5 cm or more, the entanglement of short fibers is enhanced in the web after passing through the card, and the transportability of the web to the needle punching process and the spunlacing process described later is improved, and as a result, the sound absorbing material is used. It is possible to improve the productivity of the non-woven fabric for use. In the above points, the fiber length of the staple fiber A is more preferably in the range of 3.0 to 4.5 cm.

The nonwoven fabric for sound absorbing material of the present invention may contain staple fibers A other than staple fibers A and staple fibers C having a fineness of 1.0 dtex or more as long as the sound absorbing performance of the sound absorbing material is not impaired. The staple fiber C can be appropriately used in order to improve the dispersibility of the staple fiber A in the carding process and to obtain the strength of the non-woven fabric for sound absorbing material as a sound absorbing material. Here, as the material constituting the short fiber C, a thermoplastic resin such as a polyester resin, a polyamide resin, an acrylic resin, and a polyolefin resin can be used.

In the non-woven fabric for sound absorbing material according to the present invention, the short fibers A as described above are contained in an amount of 30% by mass or more with respect to the total mass of the non-woven fabric for sound absorbing material. A porous portion having a large number of fine pores can be formed inside the fabric, and the sound is generated by air friction with the fibers around the voids as the sound passes through the voids (that is, the porous portions) between the fibers. Can be efficiently converted into heat, and excellent sound absorption can be obtained when used as a sound absorbing material. On the other hand, by setting the content of the staple fiber A as described above to 80% by mass or less with respect to the total mass of the non-woven fabric for sound absorbing material, it is extremely effective to generate thread breakage of the staple fiber A generated in the card process. Can be suppressed. In the above points, the content of the staple fibers A is preferably 40% by mass or more, more preferably 45% by mass or more, based on the total mass of the nonwoven fabric for sound absorbing material. Further, it is preferably 70% by mass or less, and more preferably 65% by mass or less.

Here, as the material constituting the short fiber A, a thermoplastic resin such as a polyester resin, a polyamide resin, an acrylic resin, or a polyolefin resin can be used. Among these, the staple fiber A is made of a polyester resin because it has excellent heat resistance, that is, it can reduce deformation and discoloration of the non-woven fabric for sound absorbing material in a high temperature environment when used in an engine room of an automobile or the like. Fibers (polyester-based staple fibers) are preferable, and among them, short fibers (polyester terephthalate staple fibers) made of polyethylene terephthalate resin having excellent heat resistance are more preferable.

Further, as the material constituting the short fiber B, a thermoplastic resin such as a polyester resin, a polyamide resin, an acrylic resin, or a polyolefin resin can be used. Among these, the short fiber B is a short fiber made of polypropylene resin (polypropylene short fiber) preferably used as a component of the split type composite fiber, or a short fiber made of nylon 6 resin (nylon 6 short fiber). Is preferable.

The basis weight of the nonwoven fabric for sound absorbing material of the present invention is preferably 150 g / m ² or more and 500 g / m ² or less. By setting the basis weight to 150 g / m ² or more, the sound absorption performance due to air friction can be improved. On the other hand, by setting the basis weight to 500 g / m ² or less, the flexibility can be improved, and a non-woven fabric for a sound absorbing material having excellent three-dimensional followability when used as an automobile member or the like can be obtained. From the above viewpoint, the basis weight is preferably 200 g / m ² or more, and more preferably 250 g / m ² or more. The upper limit of the basis weight is preferably 400 g / m ² or less, and more preferably 350 g / m ² or less.

The thickness of the non-woven fabric for sound absorbing material is preferably 0.6 mm or more and 4.0 mm or less. By setting the thickness to 0.6 mm or more, a porous portion of sufficient size is formed in the non-woven fabric for sound absorbing material, and the heat of the sound due to air friction when the sound penetrates in the thickness direction of the non-woven fabric for sound absorbing material. The conversion to can be made more efficient. On the other hand, by making the thickness 4.0 mm or less, the non-woven fabric for sound absorbing material has a more dense structure, fine porous parts are formed by the short fibers A, and the conversion of sound into heat by air friction becomes more. It can be made efficient, and as a result, the sound absorbing performance when the non-woven fabric for sound absorbing material is used as the sound absorbing material becomes more excellent. From the above viewpoint, the thickness is preferably 0.7 mm or more, more preferably 0.8 mm or more. The upper limit of the thickness is preferably 3.0 mm or less, more preferably 2.5 mm or less. The thickness of the present invention is measured by the thickness when a pressure of 0.36 kPa is applied to the nonwoven fabric based on the JIS L1913: 1998 6.1.2 A method.

The density of the non-woven fabric for sound absorbing material is preferably 0.07 g / cm ³ or more and 0.40 g / cm ³ or less. By setting the density to 0.07 g / cm ³ or more, the non-woven fabric for sound absorbing material has a dense structure, fine porous portions are formed by the short fibers A, and the conversion of sound into heat by air friction is more efficient. As a result, the sound absorbing performance when the non-woven fabric for sound absorbing material is used as the sound absorbing material becomes more excellent. On the other hand, when the density is 0.40 g / cm ³ or less, a porous portion having a sufficient size is formed in the non-woven fabric for sound absorbing material, and the sound absorbing performance due to air friction becomes more excellent. From the above viewpoint, the density is preferably 0.09 g / cm ³ or more, and more preferably 0.10 g / cm ³ or more. The upper limit of the density is preferably 0.35 g / cm ³ or less, and more preferably 0.32 g / cm ³ or less.

The nonwoven fabric for sound absorbing material preferably has a pore diameter distribution in which pores having a diameter of 5 μm or more and less than 10 μm are 10 to 90%, and pores having a diameter of 10 μm or more and less than 15 μm are 5 to 70%. By having such a fine pore size distribution, the conversion of sound by air friction into heat can be made more efficient, and as a result, sound absorption when a non-woven fabric for sound absorbing material is used as a sound absorbing material. The performance will be better. In the above points, it is more preferable to have a pore diameter distribution in which pores having a diameter of 5 μm or more and less than 10 μm are 15 to 85%, and pores having a diameter of 10 μm or more and less than 15 μm are 7 to 60%. In particular, it is more preferable to have a pore diameter distribution in which pores having a diameter of 5 μm or more and less than 10 μm are 20 to 80%, and pores having a diameter of 10 μm or more and less than 15 μm are 10 to 50%. The pore size distribution is measured by the method specified in ASTM F316-86.

The air permeability of the nonwoven fabric for sound absorbing material of the present invention is preferably 4 to 35 cm ³ / cm ² / s. When the air permeability of the non-woven fabric for sound absorbing material is 4 cm ³ / cm ² / s or more, the sound absorbing performance of the non-woven fabric for sound absorbing material due to air friction becomes more excellent, which is preferable. From the above viewpoint, the air permeability is preferably 5 cm ³ / cm ² / s or more, and particularly preferably 6 cm ³ / cm ² / s or more. On the other hand, it is preferable that the air permeability of the non-woven fabric for sound absorbing material is 35 cm ³ / cm ² / s or less because the sound absorbing performance due to air friction is improved. From the above viewpoint, the air permeability is preferably 30 cm ³ / cm ² / s or less, and more preferably 20 cm ³ / cm ² / s or less. The air permeability is measured according to JIS L 1096-1999 8.27.1 A method (Frazil type method).

Next, a preferable manufacturing method for manufacturing the nonwoven fabric for sound absorbing material of the present invention will be described. The preferred method for producing a nonwoven fabric of the present invention has the following steps.
(A) A step of opening the staple fiber A and the split type composite fiber capable of generating the staple fiber B, and
(B) A step of forming a web-like split-type composite fiber capable of generating staple fibers A and B to obtain a mixed fiber web, and
(C) The step comprises a step of entwining the short fibers A and the split type composite fibers contained in the above-mentioned mixed fiber web with a needle or a water stream to obtain a nonwoven fabric.

Hereinafter, the details of these steps (a) to (c) will be described.

First, (a) a step (opener step) of opening a split type composite fiber capable of generating short fibers A and B will be described.

In the opener step, split-type composite fibers (hereinafter, each) capable of generating short fibers A and short fibers B so that the content of short fibers A and the content of short fibers B in the non-woven fabric for sound absorbing material are desired are desired. After weighing (also referred to as short fibers), each short fiber is sufficiently opened and mixed using air or the like.

Next, a step (card step) of (b) forming the short fibers A and the split-type composite fibers capable of generating the short fibers B into a web shape and obtaining a mixed fiber web will be described.

In the card process, each of the mixed short fibers obtained in the opener process is aligned with a staple cloth roller to obtain a mixed fiber web.

Here, the content of the short fibers A contained in the mixed fiber web is 30 to 80% by mass with respect to the entire mixed fiber web. The content of the split type composite fiber contained in the mixed fiber web is 20 to 70% by mass with respect to the entire mixed fiber web.

Next, a step (c) of entwining the short fibers A and the split type composite fibers capable of generating the short fibers B by a needle or a water stream to obtain a nonwoven fabric (entanglement step) will be described.

In the entanglement step, it is preferable to carry out a mechanical entanglement method by a needle punching method or a water jet punching method (water flow entanglement method) for entanglement of each short fiber. Compared with the chemical bond method, this method can densify the non-woven fabric for sound absorbing material, and it is easy to obtain the non-woven fabric for sound absorbing material having a preferable thickness and density, and it promotes the division of the split type composite fiber. , Is preferably used to generate the short fibers B.

When each short fiber is entangled by the needle punch method, it is preferable that the staple density is 200 lines / cm ² or more and the entanglement treatment is performed. More preferably, the needles are entangled at a needle density of 250 lines / cm ² or more, and particularly preferably 300 lines / cm ² or more. By setting the needle density as described above, the non-woven fabric for sound absorbing material can be densified, and the sound absorbing performance when the non-woven fabric for sound absorbing material is used as the sound absorbing material can be improved, which is preferable.

When each short fiber is entangled by the water jet punch method, it is preferable that the pressure of the water jet punch nozzle is 12.0 MPa or more and the water nozzle is passed through the water nozzle three times or more. By setting the pressure of the water jet punch nozzle to 12.0 MPa or more, the non-woven fabric for sound absorbing material can be densified, and short fibers B are efficiently generated from the split type composite fiber to absorb sound from the non-woven fabric for sound absorbing material. It is preferable because it can improve the sound absorption performance when used as a material. Further, by passing the water nozzle three times or more, the non-woven fabric for sound absorbing material can be densified in the same manner as described above, and the short fibers B can be efficiently generated from the split type composite fiber, and the non-woven fabric for sound absorbing material can be used as the sound absorbing material. It is preferable because it can improve the sound absorption performance when used. As a method of passing the water nozzle, there are a method of passing the water nozzle three times or more in succession, or a method of winding the non-woven fabric through the water nozzle once and then passing the water nozzle again, which is preferable in terms of improving productivity. It is a method of passing it three times or more.

When entwining fibers by the water jet punch method, if the surface that first faces upward and contacts the nozzle surface is the front surface and the opposite surface is the back surface, the surface that allows water flow from the nozzle is the front surface / back surface / front surface or front surface / back surface. It can be set arbitrarily such as / back surface, front surface / front surface / back surface / front surface / back surface.

In particular, the water jet punch method can efficiently entangle short fibers having a fine fineness without thread breakage in the entanglement process, and further efficiently divide the short fibers B from the split type composite fibers to obtain the short fibers B. Since it can be generated, the staple fibers A having a fineness of 0.4 to 0.9 dtex and the passage coefficient defined above of 15 to 260 and the staple fibers B having a fineness of 0.0005 to 0.3 dtex are produced. It can be suitably used for producing the non-woven fiber for a sound absorbing material of the present invention.

Next, the sound absorbing material will be described. The sound absorbing material provided with the non-woven fabric for sound absorbing material of the present invention has the non-woven fabric for sound absorbing material of the present invention and a layered material composed of a fibrous porous body layer, a foam layer, or an air layer. The layered material is laminated on one surface of the non-woven fabric for sound absorbing material. In such a sound absorbing material, the sound absorbing performance of the sound absorbing material can be improved by using the sound absorbing material so that the above-mentioned layered material is located on the surface opposite to the surface on the side where the sound of the non-woven fabric for sound absorbing material is incident. It will be excellent. The thickness of the layered material is preferably 5 to 50 mm. The layered material is preferably a fibrous porous body, a foam, or an air layer. That is, the nonwoven fabric for sound absorbing material of the present invention is a fiber-based porous body using a thermoplastic resin fiber having a thickness of 5 to 50 mm or a fiber using an inorganic fiber on the surface opposite to the surface on the side where sound is incident. The sound absorption performance of these composite products (sound absorbing materials) becomes extremely excellent by using a base material made of a porous material, a base material made of a foam material such as urethane foam, or the like by laminating them. Further, by providing an air layer having a thickness of 5 to 50 mm on the surface opposite to the surface on the side where the sound of the sound absorbing material nonwoven fabric of the present invention is incident, a composite product (sound absorbing material) of the laminated nonwoven fabric for sound absorbing material and the air layer is provided. The sound absorption performance of the material) is extremely excellent.

The measurement method used in this example will be described later.

(Measuring method)
(1) Each short fiber and content constituting the non-woven fabric for sound absorbing material JIS L 1030-1: 2006 "Mixing ratio test method for textile products-Part 1: Fiber identification", and JIS L 1030-2: 2005 "Fiber". Based on "Product mixing ratio test method-Part 2: Fiber mixing ratio", the positive amount mixing ratio (mass ratio of each staple fiber in the standard state) is measured, and this is used to contain the fibers that make up the non-woven fabric for sound absorbing material. The amount (% by mass) was used. As a result, the fiber material constituting the non-woven fabric for sound absorbing material and its content (mass%) were specified.

(2) Fineness and content of short fibers constituting the non-woven fabric for sound absorbing material JIS L 1030-2: 2005 "Test method for mixing ratio of textile products-Part 2: Fiber mixing ratio" in (1) above. The cross section of the residual non-woven fabric in the melting method was observed with a scanning electron microscope (SEM) (S-3500N type manufactured by Hitachi High-Tech), and 30 observation ranges were randomly extracted to obtain a magnification of 1,000 times. A cross-sectional photograph was taken. Furthermore, the single fiber diameter was measured for all the fibers present in the cross-sectional photograph. When the cross-sectional shape of the fiber is an irregular cross-sectional shape, the cross-sectional area of the fiber is measured from the cross-sectional area, and the cross-sectional area is converted into a perfect circle diameter to obtain the single fiber diameter of the fiber. The obtained single fiber diameter data was sharply classified for each section of 0.1 μm, and the average single fiber diameter for each section and the number of fibers for each section were totaled. From the obtained average single fiber diameter for each section and the specific gravity of each staple fiber specified in (1) above, the fineness of the fiber for each section was calculated by the following formula (2).

Fineness (dtex) = (Average single fiber diameter (μm) / 2) ² × 3.14 × Staple density / 100 (2)
Among the fineness of the above fibers, for fibers having a fineness of 0.4 to 0.9 dtex, the fibers having a fineness of 0.4 to 0.9 dtex are based on the fineness of each section, the number of fibers in each section, and the specific gravity of the fiber material. Content (% by mass) was calculated.

Content (% by mass) of fibers having a fineness of 0.4 to 0.9 dtex = ((Fibers of fibers having a fineness of 0.4 to 0.9 dtex (dtex) x number of fibers per section (lines)) ) / (Fiberity (dtex) for each section of fibers other than 0.4 to 0.9 dtex x number of fibers (lines) for each section) x 100 (3)
Similarly, the content (% by mass) of the fiber having a fineness of 0.0005 to 0.3 dtex was determined.

When there are a plurality of fiber materials constituting the non-woven fabric for sound absorbing material, the above-mentioned fineness and content are measured for each fiber material using the residual non-woven fabric in the dissolution method to form the non-woven fabric for sound absorbing material. The fineness and content of the fiber to be used were determined.

(3) Fiber length of short fibers constituting the non-woven fabric for sound absorbing material JIS L 1015: 2010 8.4.1 The unit was measured in cm by the direct method (C method).

(4) Strength and elongation of the short fibers constituting the non-woven fabric for sound absorbing material Based on JIS L 1015 (1999) 8.7.1, the space distance is 20 mm, and the short fibers are loosely stretched one by one on the dividing line. Both ends are attached to a piece of paper with an adhesive and fixed, and each category is made into one sample. Attach the sample to the grip of the tensile tester, cut a piece of paper near the upper grip, pull at a grip interval of 20 mm and a tensile speed of 20 mm / min, and apply the load (N) and elongation (mm) when the sample is cut. Measurement, tensile strength (cN / dtex) and elongation (%) were calculated by the following formulas.
Tb = SD / F0
Tb: Tensile strength (cN / dtex)
SD: Load at break (cN)
F0: Positive fineness of the sample (dtex)
S = {(E2-E1) / (L + E1)} × 100
S: Elongation (%)
E1: Looseness (mm)
E2: Elongation at cutting (mm) or elongation at maximum load (mm)
L: Grab interval (mm)
(5) Number of crimps of short fibers constituting non-woven fabric for sound absorbing material Number of crimps of fibers constituting non-woven fabric according to the method of JIS L 1015-8-12-1, 2 (2010 revised edition) 25 mm) was measured.

(6) Degree of crimping of short fibers constituting the non-woven fabric for sound absorbing material The crimping rate (%) of the fibers constituting the non-woven fabric according to the method of JIS L 1015-8-12-1, 2 (2010 revised edition). Was measured, and this was taken as the degree of crimping (%) of the fiber.

(7) Card process pass rate (productivity and quality)
Adjust to the short fiber ratio to be used, weigh 20 g of raw cotton processed in the opener process, put it in a lab card machine (cylinder rotation speed 300 rpm, doffer speed 10 m / min), and drop cotton in the card process due to thread breakage. Measure the mass (g) of the web coming out of the card without wrapping it around the or staple cloth. Using the measured mass of the web and the like, the card process pass rate was calculated by the following formula. It can be said that the larger the value of the card process pass rate, the better the card process pass rate. Card process pass rate (%) = web mass (g) / input amount (g) × 100.

In addition, the appearance of the obtained nonwoven fabric for sound absorbing material was visually observed. Three 300 mm × 300 mm test pieces were collected from a sample of non-woven fabric for sound absorbing material using a steel ruler and a razor blade, and the number of fiber lumps was counted and converted into the number of fiber lumps (pieces / m ² ). ..

(8) Metsuke of non-woven fabric for sound absorbing material Measured based on JIS L 1913: 1998 6.2. Three 300 mm × 300 mm test pieces were collected from a sample of the non-woven fabric for sound absorbing material using a steel ruler and a razor blade. The mass of the test piece in the standard state was measured, and the basis weight, which is the mass per unit area, was calculated by the following formula, and the average value was calculated.
ms = m / S
ms: Mass per unit area (g / m ² )
m: Average mass (g) of test piece of non-woven fabric for sound absorbing material
S: Area of test piece of non-woven fabric for sound absorbing material (m ² )
(9) Thickness of non-woven fabric for sound absorbing material Measured based on JIS L1913: 1998 6.1.2 A method. Five 50 mm × 50 mm test pieces were collected from a sample of the non-woven fabric for sound absorbing material. Using a thickness measuring device (constant pressure thickness measuring device manufactured by TECLOCK, model PG11J), the thickness was measured by applying a pressure of 0.36 kPa to the test piece in a standard state over 10 seconds. The measurement was performed on each test piece (5 pieces), and the average value was calculated.

(10) Density of non-woven fabric for sound absorbing material From the basis weight of the laminated non-woven fabric for sound absorbing material of (8) above and the thickness of the laminated non-woven fabric for sound absorbing material of (9) above, it was determined by the following formula.

Density of non-woven fabric for sound absorbing material (g / cm ³ ) = Texture of non-woven fabric for sound absorbing material (g / m ² ) / Thickness of non-woven fabric for sound absorbing material (mm) / 1000
(11) Pore diameter distribution of non-woven fabric for sound absorbing material Measured by the method specified in ASTM F316-86. A "Palm Porometer" manufactured by Pourous Materials, Inc. (USA) is used as the measuring device, "Galvic" manufactured by PMI is used as the measuring reagent, the cylinder pressure is 100 kPa, and the measuring mode is WET UP-DRY UP. The pore size distribution (%) was measured under the above conditions, and the pore size distribution (%) of 5 μm or more and less than 10 μm, 10 μm or more and less than 15 μm, and 15 μm or more and less than 20 μm was shown.

(12) Air permeability of non-woven fabric for sound absorbing material Measured according to JIS L 1096-1999 8.27.1 A method (Frazil type method). Five 200 mm × 200 mm test pieces were collected from a sample of the non-woven fabric for sound absorbing material. A test piece was attached to one end (intake side) of the cylinder using a Frazier type tester. When mounting the test piece, the test piece was placed on a cylinder, and a load of about 98 N (10 kgf) was evenly applied from above the test piece so as not to block the intake portion to prevent air leakage at the test piece mounting portion. After attaching the test piece, adjust the suction fan so that the inclined barometer shows a pressure of 125 Pa with an adjusting resistor, and from the pressure shown by the vertical barometer at that time and the type of air hole used, The air flow rate (cm ³ / cm ² / s) passing through the test pieces was determined from the table attached to the tester, and the average value for the five test pieces was calculated.

(13) Vertically incident sound absorption coefficient of non-woven fabric for sound absorbing material The measurement was performed according to the vertical incident sound absorption measuring method (in-pipe method) of JIS A 1405 (1998). Three circular test pieces having a diameter of 92 mm were collected from a sample of the non-woven fabric for sound absorbing material. As a test device, an automatic vertical incident sound absorption coefficient measuring device (model 10041A) manufactured by Electronic Measuring Instruments Co., Ltd. was used. A spacer was installed at one end of the impedance tube for measurement so that an air layer having a thickness of 20 mm could be formed between the test piece and the metal reflector, and the test piece was attached. For the sound absorption coefficient for each frequency, a value obtained by multiplying the sound absorption coefficient obtained by the measurement by 100 was adopted. Then, the average value of the obtained 1000 Hz sound absorption coefficient was defined as the low frequency sound absorption coefficient (%), and the average value of the obtained 2000 Hz sound absorption coefficient was defined as the high frequency sound absorption coefficient (%).

(Example 1)
As short fiber A, the fineness is 0.56 dtex, the fiber length is 3.8 cm, the strength is 5.4 cN / dtex, the elongation is 23%, the number of crimps is 13.4 threads / 25 mm, the crimp degree is 15.3%, and the passage coefficient is 55. Polybutylene terephthalate (PET) short fiber is 50% by mass, and as a short fiber capable of generating short fiber B, the fineness is 2.05 dtex, the fiber length is 5.1 cm, and the fineness of the short fiber B after division is 0.008 dtex. 50% by mass of split composite short fibers (PP: PBT mass ratio = 10: 90) of (PP) and polybutylene terephthalate (PBT) are used, and after each short fiber is subjected to an opener step, a card step (cylinder) is performed. It was subjected to a rotation speed of 300 rpm and a doffer speed of 10 m / min). Then, it was subjected to a water flow entanglement step (pressure condition: upper surface 8.0 MPa, upper surface 10.0 MPa, lower surface 13.5 MPa, upper surface 16.0 MPa, lower surface 13.5 MPa 5 times) under the following conditions, and then subjected to a drying step. And dried at 120 ° C. to obtain a nonwoven fabric for sound absorbing material having a staple fiber B content of 5% by mass, a grain of 200 g / m ² , a thickness of 1.4 mm, and a nonwoven fabric density of 0.143 g / cm ³ .

The non-woven fabric for sound absorbing material of Example 1 had no cotton drop due to thread breakage in the card process or wrapping around the needle cloth, and had a good card process passability of 92%. In addition, the dispersion of each staple fiber was good, the generation of fiber lumps was small, and the quality was good.

The low-frequency sound absorption coefficient and the high-frequency sound absorption coefficient of the obtained laminated non-woven fabric for sound absorbing material were high.

(Example 2)
Except for the fact that the short fiber A of Example 1 was used as the short fiber A and the split type composite short fiber of Example 1 was used as the split type composite short fiber, and the contents were changed to 35% by mass and 65% by mass, respectively. Treated under the same steps and conditions as in Example 1, a non-woven fabric for sound absorbing material having a staple fiber B content of 7% by mass, a texture of 200 g / m ² , a thickness of 1.4 mm, and a non-woven fabric density of 0.143 g / cm ³ was prepared. Obtained.

The non-woven fabric for sound absorbing material of Example 2 had no cotton drop due to thread breakage in the card process or wrapping around the needle cloth, and had a good card process passability of 93%. In addition, the dispersion of each staple fiber was good, the generation of fiber lumps was small, and the quality was also good.

The low-frequency sound absorption coefficient and the high-frequency sound absorption coefficient of the obtained nonwoven fabric for sound absorbing material were high.

(Example 3)
Except for the fact that the short fiber A of Example 1 was used as the short fiber A and the split type composite short fiber of Example 1 was used as the split type composite short fiber, and the contents were changed to 75% by mass and 25% by mass, respectively. Treated under the same steps and conditions as in Example 1, a non-woven fabric for sound absorbing material having a staple fiber B content of 3% by mass, a texture of 200 g / m ² , a thickness of 1.4 mm, and a non-woven fabric density of 0.143 g / cm ³ was prepared. Obtained.

The non-woven fabric for sound absorbing material of Example 3 had no cotton drop due to thread breakage in the card process or wrapping around the needle cloth, and had a good card process passability of 90%. In addition, the dispersion of each staple fiber was good, the generation of fiber lumps was relatively small, and the quality was also relatively good.

The low-frequency sound absorption coefficient and the high-frequency sound absorption coefficient of the obtained nonwoven fabric for sound absorbing material were high.

(Example 4)
As a staple fiber A, the fineness is 0.56 dtex, the fiber length is 3.8 cm, the strength is 5.4 cN / dtex, the elongation is 24%, the number of crimps is 7.5 peaks / 25 mm, the crimp degree is 9.1%, and the passage coefficient is 32. Treatment was performed under the same steps and conditions as in Example 1 except that 50% by mass of polyethylene terephthalate (PET) short fibers and 50% by mass of the split type composite staple fibers of Example 1 were used as the split type composite staple fibers. A nonwoven fabric for a sound absorbing material having a fiber B content of 5% by mass, a texture of 200 g / m ² , a thickness of 1.4 mm, and a nonwoven fabric density of 0.143 g / cm ³ was obtained.

The non-woven fabric for sound absorbing material of Example 4 had relatively little cotton drop due to thread breakage in the card process and wrapping around the needle cloth, and the card process passability was relatively good at 82%. In addition, the dispersion of each staple fiber was good, the generation of fiber lumps was relatively small, and the quality was also relatively good.

The low-frequency sound absorption coefficient and the high-frequency sound absorption coefficient of the obtained nonwoven fabric for sound absorbing material were high.

(Example 5)
As a staple fiber A, the fineness is 0.56 dtex, the fiber length is 3.8 cm, the strength is 4.7 cN / dtex, the elongation is 24%, the number of crimps is 13.5 threads / 25 mm, the crimp degree is 15.2%, and the passage coefficient is 49. Treatment was performed under the same steps and conditions as in Example 1 except that 50% by mass of polyethylene terephthalate (PET) short fibers and 50% by mass of the split type composite staple fibers of Example 1 were used as the split type composite staple fibers. A nonwoven fabric for a sound absorbing material having a fiber B content of 5% by mass, a texture of 200 g / m ² , a thickness of 1.4 mm, and a nonwoven fabric density of 0.143 g / cm ³ was obtained.

The non-woven fabric for sound absorbing material of Example 5 had relatively little cotton drop due to thread breakage in the card process and wrapping around the needle cloth, and the card process passability was relatively good at 87%. In addition, the dispersion of each staple fiber was good, the generation of fiber lumps was relatively small, and the quality was also relatively good.

The low-frequency sound absorption coefficient and the high-frequency sound absorption coefficient of the obtained nonwoven fabric for sound absorbing material were high.

(Example 6)
As a staple fiber A, the fineness is 0.57 dtex, the fiber length is 3.8 cm, the strength is 6.3 cN / dtex, the elongation is 24%, the number of crimps is 13.5 threads / 25 mm, the crimp degree is 15.3%, and the passage coefficient is 67. Treatment was performed under the same steps and conditions as in Example 1 except that 50% by mass of polyethylene terephthalate (PET) short fibers and 50% by mass of the split type composite staple fibers of Example 1 were used as the split type composite staple fibers. A nonwoven fabric for a sound absorbing material having a fiber B content of 5% by mass, a texture of 200 g / m ² , a thickness of 1.4 mm, and a nonwoven fabric density of 0.143 g / cm ³ was obtained.

The non-woven fabric for sound absorbing material of Example 6 had no cotton drop due to thread breakage in the card process or wrapping around the needle cloth, and had a good card process passability of 94%. In addition, the dispersion of each staple fiber was good, the generation of fiber lumps was small, and the quality was also good.

The low-frequency sound absorption coefficient and the high-frequency sound absorption coefficient of the obtained nonwoven fabric for sound absorbing material were high.

(Example 7)
50% by mass of the short fiber A of Example 1 was used as the short fiber A, and 50% by mass of the split type composite short fiber of Example 1 was used as the split type composite short fiber, and the staple fibers were treated under the same steps and conditions as in Example 1. A nonwoven fabric for a sound absorbing material having a staple fiber B content of 5% by mass, a grain of 140 g / m ² , a thickness of 1.1 mm, and a nonwoven fabric density of 0.127 g / cm ³ was obtained.

The non-woven fabric for sound absorbing material of Example 7 had no cotton drop due to thread breakage in the card process or wrapping around the needle cloth, and had a good card process passability of 92%. In addition, the dispersion of each staple fiber was good, the generation of fiber lumps was small, and the quality was also good.

The low-frequency sound absorption coefficient of the obtained nonwoven fabric for sound-absorbing material was relatively high, and the high-frequency sound absorption coefficient was high.

(Example 8)
50% by mass of the short fiber A of Example 1 was used as the short fiber A, and 50% by mass of the split type composite short fiber of Example 1 was used as the split type composite short fiber. The pressure condition was changed to 8.0 MPa on the upper surface, 10.0 MPa on the upper surface, 11.0 MPa on the lower surface, 11.0 MPa on the upper surface, and 11.0 MPa on the lower surface. A nonwoven fabric for a sound absorbing material having a fiber B content of 5% by mass, a texture of 200 g / m ² , a thickness of 4.1 mm, and a nonwoven fabric density of 0.049 g / cm ³ was obtained.

The non-woven fabric for sound absorbing material of Example 8 had no cotton drop due to thread breakage in the card process or wrapping around the needle cloth, and had a good card process passability of 92%. In addition, the dispersion of each staple fiber was good, the generation of fiber lumps was small, and the quality was also good.

The low-frequency sound absorption coefficient of the obtained nonwoven fabric for sound-absorbing material was relatively high, and the high-frequency sound absorption coefficient was high.

(Example 9)
As a staple fiber A, the fineness is 0.58 dtex, the fiber length is 3.8 cm, the strength is 3.5 cN / dtex, the elongation is 23%, the number of crimps is 13.1 peaks / 25 mm, the crimp degree is 15.5%, and the passage coefficient is 37. Treatment was performed under the same steps and conditions as in Example 1 except that 50% by mass of the acrylic short fibers and 50% by mass of the split type composite staple fibers of Example 1 were used as the split type composite staple fibers, and the short fibers B were contained. A non-woven fiber for a sound absorbing material having an amount of 5% by mass, a grain of 200 g / m ² , a thickness of 1.4 mm, and a non-woven fiber density of 0.143 g / cm ³ was obtained.

The non-woven fabric for sound absorbing material of Example 9 had no cotton drop due to thread breakage in the card process or wrapping around the needle cloth, and had a good card process passability of 91%. In addition, the dispersion of each staple fiber was good, the generation of fiber lumps was small, and the quality was also good.

The low-frequency sound absorption coefficient and the high-frequency sound absorption coefficient of the obtained nonwoven fabric for sound absorbing material were high.

(Comparative Example 1)
Except for the fact that the short fiber A of Example 1 was used as the short fiber A and the split type composite short fiber of Example 1 was used as the split type composite short fiber, and the contents were changed to 20% by mass and 80% by mass, respectively. Treated under the same steps and conditions as in Example 1, a non-woven fabric for sound absorbing material having a staple fiber B content of 8% by mass, a texture of 200 g / m ² , a thickness of 1.4 mm, and a non-woven fabric density of 0.143 g / cm ³ was prepared. Obtained.

The non-woven fabric for sound absorbing material of Comparative Example 1 had relatively little cotton drop due to thread breakage in the card process and wrapping around the needle cloth, and the card process passability was relatively good at 85%. In addition, the dispersion of each staple fiber was good, the generation of fiber lumps was relatively small, and the quality was also relatively good.

The low-frequency sound absorption coefficient and the high-frequency sound absorption coefficient of the obtained nonwoven fabric for sound absorbing material were low.

(Comparative Example 2)
Except for the fact that the short fiber A of Example 1 was used as the short fiber A and the split type composite short fiber of Example 1 was used as the split type composite short fiber, and the contents were changed to 90% by mass and 10% by mass, respectively. Treated under the same steps and conditions as in Example 1, a non-woven fabric for sound absorbing material having a staple fiber B content of 1% by mass, a texture of 200 g / m ² , a thickness of 1.4 mm, and a non-woven fabric density of 0.143 g / cm ³ was prepared. Obtained.

The non-woven fabric for sound absorbing material of Comparative Example 2 had a lot of cotton falling and wrapping around the needle cloth due to thread breakage in the card process, and the card process passability was as poor as 68%. In addition, the dispersibility of the fibers was low, the generation of fiber lumps increased, and the quality was inferior.

The low-frequency sound absorption coefficient and the high-frequency sound absorption coefficient of the obtained nonwoven fabric for sound absorbing material were low.

(Comparative Example 3)
As the short fiber A, the short fiber A of Example 1 is 50% by mass, and as the short fiber capable of generating the short fiber B, the fineness is 2.05 dtex, the fiber length is 5.1 cm, and the fineness of the short fiber B after division is 0. 50% by mass of a split type composite short fiber (PP: PBT mass ratio = 2: 98) of polypropylene (PP) to be 008 dtex and polybutylene terephthalate (PBT) was used and treated under the same steps and conditions as in Example 1. A sound absorbing non-woven material having a short fiber B content of 1% by mass, a grain of 200 g / m ² , a thickness of 1.4 mm, and a non-woven fabric density of 0.143 g / cm ³ was obtained.

The non-woven fabric for sound absorbing material of Comparative Example 3 had no cotton drop due to thread breakage in the card process or wrapping around the needle cloth, and had a good card process passability of 94%. In addition, the dispersion of each staple fiber was good, the generation of fiber lumps was small, and the quality was also good.

The low-frequency sound absorption coefficient of the obtained nonwoven fabric for sound-absorbing material was low, and the high-frequency sound absorption coefficient was relatively high.

(Comparative Example 4)
As a staple fiber A, the fineness is 0.34 dtex, the fiber length is 3.8 cm, the strength is 5.4 cN / dtex, the elongation is 23%, the number of crimps is 13.4 threads / 25 mm, the crimp degree is 15.3%, and the passage coefficient is 36. 50% by mass of polyethylene terephthalate (PET) short fibers and 50% by mass of the split type composite short fibers of Example 1 were used as the split type composite short fibers, and the short fibers B were treated under the same steps and conditions as in Example 1. A non-woven fabric for a sound absorbing material having a content of 5% by mass, a texture of 200 g / m ² , a thickness of 1.4 mm, and a non-woven fabric density of 0.143 g / cm ³ was obtained.

The non-woven fabric for sound absorbing material of Comparative Example 4 had a lot of cotton falling and wrapping around the needle cloth due to thread breakage in the card process, and the card process passability was as poor as 74%. In addition, the dispersibility of the fibers was low, the generation of fiber lumps increased, and the quality was inferior.

The low-frequency sound absorption coefficient and the high-frequency sound absorption coefficient of the obtained nonwoven fabric for sound absorbing material were low.

(Comparative Example 5)
As a staple fiber A, the fineness is 0.97 dtex, the fiber length is 3.8 cm, the strength is 5.4 cN / dtex, the elongation is 24%, the number of crimps is 13.3 peaks / 25 mm, the crimp degree is 15.4%, and the passage coefficient is 97. 50% by mass of polyethylene terephthalate (PET) short fibers and 50% by mass of the split type composite short fibers of Example 1 were used as the split type composite short fibers, and the short fibers B were treated under the same steps and conditions as in Example 1. A non-woven fabric for a sound absorbing material having a content of 5% by mass, a texture of 200 g / m ² , a thickness of 1.4 mm, and a non-woven fabric density of 0.143 g / cm ³ was obtained.

The non-woven fabric for sound absorbing material of Comparative Example 5 had no cotton drop due to thread breakage in the card process or wrapping around the needle cloth, and had a good card process passability of 95%. In addition, the dispersion of each staple fiber was good, the generation of fiber lumps was small, and the quality was also good.

The low-frequency sound absorption coefficient and the high-frequency sound absorption coefficient of the obtained nonwoven fabric for sound absorbing material were low.

(Comparative Example 6)
As a staple fiber A, the fineness is 0.55 dtex, the fiber length is 3.8 cm, the strength is 1.5 cN / dtex, the elongation is 17%, the number of crimps is 13.5 threads / 25 mm, the crimp degree is 15.2%, and the passage coefficient is 13. 50% by mass of polyethylene terephthalate (PET) short fibers and 50% by mass of the split type composite short fibers of Example 1 were used as the split type composite short fibers, and the short fibers B were treated under the same steps and conditions as in Example 1. A non-woven fabric for a sound absorbing material having a content of 5% by mass, a texture of 200 g / m ² , a thickness of 1.4 mm, and a non-woven fabric density of 0.143 g / cm ³ was obtained.

The non-woven fabric for sound absorbing material of Comparative Example 6 had a lot of cotton falling and wrapping around the needle cloth due to thread breakage in the card process, and the card process passability was as poor as 67%. In addition, the dispersibility of the fibers was low, the generation of fiber lumps increased, and the quality was inferior.

The low-frequency sound absorption coefficient and the high-frequency sound absorption coefficient of the obtained nonwoven fabric for sound absorbing material were low.

(Comparative Example 7)
As a staple fiber A, the fineness is 0.56 dtex, the fiber length is 3.8 cm, the strength is 4.8 cN / dtex, the elongation is 21%, the number of crimps is 4.0 threads / 25 mm, the crimp degree is 4.5%, and the passage coefficient is 14. 50% by mass of polyethylene terephthalate (PET) short fibers and 50% by mass of the split type composite short fibers of Example 1 were used as the split type composite short fibers, and the short fibers B were treated under the same steps and conditions as in Example 1. A non-woven fabric for a sound absorbing material having a content of 5% by mass, a texture of 200 g / m ² , a thickness of 1.4 mm, and a non-woven fabric density of 0.143 g / cm ³ was obtained.

The non-woven fabric for sound absorbing material of Comparative Example 7 had many cotton drops and wrapping around the needle cloth due to thread breakage in the card process, and the card process passability was as poor as 69%. In addition, the dispersibility of the fibers was low, the generation of fiber lumps increased, and the quality was inferior.

The low-frequency sound absorption coefficient and the high-frequency sound absorption coefficient of the obtained nonwoven fabric for sound absorbing material were low.

The configurations and characteristics of the nonwoven fabrics for sound absorbing materials of Examples and Comparative Examples are summarized in Tables 1 to 4.

The nonwoven fabric for a sound absorbing material of the present invention is excellent in sound absorbing performance in a low frequency region and a high frequency region, is excellent in productivity, and is also excellent in quality, so that it is particularly preferably used as a sound absorbing material for automobiles and the like.

Claims (7)

Contains 30-80% by mass of short fibers A having a fineness of 0.4 to 0.9 dtex.
Contains 2% by mass or more of staple fibers B having a fineness of 0.0005 to 0.3 dtex.
A non-woven fabric for a sound absorbing material, wherein the passing coefficient of the staple fiber A shown in the following formula (1) is in the range of 15 to 260.
Passing coefficient = (fineness x strength x √ elongation x √ number of crimps x √ crimp degree) / (fiber length) (1)
<Fineness (dtex), strength (cN / dtex), elongation (%), number of crimps (mountain / 25 mm), crimp degree (%), fiber length (cm)> The basis weight is 150 g / m ² or more and 500 g / m ² or less.
The nonwoven fabric for a sound absorbing material according to claim 1, which has a thickness of 0.6 mm or more and 4.0 mm or less. The nonwoven fabric for a sound absorbing material according to claim 1 or 2, wherein the density is 0.07 g / cm ³ or more and 0.40 g / cm ³ or less. The nonwoven fabric for a sound absorbing material according to any one of claims 1 to 3, wherein the staple fiber A is a polyester-based staple fiber. The tensile strength of the staple fiber A is 5 cN / dtex or more, and the staple fiber A has a tensile strength of 5 cN / dtex or more.
The nonwoven fabric for a sound absorbing material according to any one of claims 1 to 4, wherein the staple fiber A has a tensile elongation of 20 to 35%. The nonwoven fabric for sound absorbing material according to any one of claims 1 to 5.
It has a layered material composed of a fibrous porous body layer, a foam layer, or an air layer, and has.
The layered material is laminated on one surface of the non-woven fabric for sound absorbing material.
A sound absorbing material having a layered material having a thickness of 5 to 50 mm. A step of subjecting the staple fiber A and the split type composite fiber to a fiber opening treatment to obtain a mixed fiber web of the staple fiber A and the split type composite fiber.
The mixed fiber web has a step of passing through the water jet punch nozzle three times or more, and the short fiber B is divided from the split type composite fiber.
The staple fiber A has a fineness of 0.4 to 0.9 dtex, and has a fineness of 0.4 to 0.9 dtex.
The passage coefficient of the staple fiber A shown in the following formula (1) is in the range of 15 to 260.
The fineness of the staple fiber B is 0.0005 to 0.3 dtex, and the staple fiber B has a fineness of 0.0005 to 0.3 dtex.
The content of the staple fiber A is 30 to 80% by mass with respect to the entire mixed fiber web.
A method for producing a nonwoven fabric for a sound absorbing material, wherein the content of the split type composite fiber is 20 to 70% by mass with respect to the entire mixed fiber web.
Passing coefficient = (fineness x strength x √ elongation x √ number of crimps x √ crimp degree) / (fiber length) (1)
<Fineness (dtex), strength (cN / dtex), elongation (%), number of crimps (mountain / 25 mm), crimp degree (%), fiber length (cm)>