JP2022040591A - Non-woven fabric for sound absorption material, sound absorption material and manufacturing method of non-woven fabric for sound absorption material - Google Patents

Abstract

To provide a non-woven fabric for sound absorption material and a sound absorption material, which are excellent in sound absorption performance of a low frequency region, excellent in productivity and excellent in quality, and to provide a manufacturing method of the non-woven fabric for sound absorption material.SOLUTION: A non-woven fabric for sound absorption material has a laminated structure of a non-woven fabric A and a non-woven fabric B. The non-woven fabric A contains 80% by mass or more of fibers A1 with fineness of 0.002 to 0.3 dtex with respect to the entire non-woven fabric A, and the non-woven fabric B contains 30 to 80% by mass of short fibers A2 having fineness of 0.4 to 0.9 dtex with respect to the entire nonwoven fabric B. The nonwoven fabric B contains 20 to 70% by mass of the short fibers B with the fineness of 1.1 to 20.0 dtex with respect to the entire nonwoven fabric B. A passing coefficient of the short fibers A2 shown in the following formula (1) is in the range of 15 to 260. Passing coefficient=(fineness×strength×√ elongation×√ number of crimps×√ crimp degree)/(fiber length) (1)<fineness (dtex), strength (cN/dtex), elongation (%), number of crimps(crimps/25 mm), crimp degree(%), fiber length (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. Further, in the field of automobiles, heat resistance that can be applied around an engine is required.

Patent Document 1 proposes a laminated non-woven fabric for a sound absorbing material in which a layer made of nanofibers and a layer of fibers thicker than nanofibers are laminated.

Further, in Patent Document 2, 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. A method for manufacturing a soundproof material for a vehicle on which a ventilation adjusting film is formed has been proposed.

Further, Patent Document 3 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 4 proposes a sound absorbing material in which a meltblown nonwoven fabric and a needle punched nonwoven fabric base material containing short fibers having a fiber diameter of 6 to 8 μm are laminated.

International Publication No. 2016/143857 Japanese Unexamined Patent Publication No. 2016-34828 International Publication No. 2020/31798 International Publication No. 2019/106757

According to the findings of the present inventors, both the laminated non-woven fabric for sound absorbing material disclosed in Patent Document 1 and the soundproofing material for vehicles disclosed in Patent Document 2 (hereinafter, non-woven fabric for sound absorbing material) contain ultrafine fibers. Therefore, there is a tendency that the soundproofing performance is 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 3 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 3 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 4 discloses that a meltblown nonwoven fabric is laminated on the surface of a needle punched nonwoven fabric base material containing ultrafine short fibers to form a sound absorbing material in order to obtain an excellent sound absorbing effect. However, Patent Document 4 does not disclose the relationship between the physical properties of the ultrafine staple fibers and the productivity, and there is a problem that the productivity in producing the 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.

Therefore, in view of the above circumstances, the present invention provides a non-woven fabric for sound absorbing material, a non-woven fabric for sound absorbing material, and a non-woven fabric for sound absorbing material, which are excellent in sound absorbing performance and productivity in a particularly low frequency region and also have excellent quality. The task is to do.

In order to solve the above problems, the present invention has the following configurations. That is,
(1) The nonwoven fabric A has a laminated structure of the nonwoven fabric A and the nonwoven fabric B, and the nonwoven fabric A contains fibers A1 having a fineness of 0.002 to 0.3 dtex in an amount of 80% by mass or more with respect to the entire nonwoven fabric A. The non-woven fabric B contains 30 to 80% by mass of short fibers A2 having a fineness of 0.4 to 0.9 dtex with respect to the entire non-woven fabric B, and the non-woven fabric B contains short fibers B having a fineness of 1.1 to 20.0 dtex as a whole. It is a non-woven fabric for a sound absorbing material, which contains 20 to 70% by mass with respect to the above, and the passing coefficient of the short fiber A2 represented by 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)>
(2) The nonwoven fabric for sound absorbing material according to (1) having a basis weight of 150 g / m ² or more and 700 g / m ² or less and a thickness of 0.6 mm or more and 4.0 mm or less is preferable.
(3) The non-woven fabric for sound absorbing material according to (1) or (2) having a density of 0.07 g / cm ³ or more and 0.40 g / cm ³ or less is preferable.
(4) The non-woven fabric for a sound absorbing material according to any one of (1) to (3), wherein the short fiber A2 is a polyester-based staple fiber, is preferable.
(5) The nonwoven fabric for sound absorbing material according to any one of (1) to (4), wherein the staple fiber A2 has a tensile strength of 5 cN / dtex or more and the staple fiber A2 has a tensile elongation of 20 to 35%. It is preferable to have
(6) The fineness of the short fiber A2 is 0.4 to 0.9 dtex, the fineness of the short fiber B is 1.1 to 1.8 dtex, and the fineness of the short fiber A2 and the short fiber B is high. It is preferable that the non-woven fabric for a sound absorbing material according to any one of (1) to (5) has a ratio (fineness of short fiber A2 / fineness of short fiber B) of 0.30 to 0.60.
(7) The non-woven fabric for a sound absorbing material according to any one of (1) to (6) and a layered material composed of a fibrous porous body, a foam, or an air layer are provided, and the layered material is the sound absorbing material. A sound absorbing material which is laminated on one surface of a non-woven fabric for use and has a thickness of the layered material of 5 to 50 mm.
(8) A step of obtaining a non-woven fabric A containing 80% by mass or more of fibers A1 having a fineness of 0.002 to 0.3 dtex with respect to the entire non-woven fabric A by a melt blow method, and an opening treatment for the short fibers A2 and the short fibers B. A step of obtaining a mixed fiber web of short fibers A2 and short fibers B, a step of passing the mixed fiber web through a water jet punch nozzle three times or more to obtain a non-woven fabric B, and a step of obtaining the non-woven fabric A and the partial woven fabric B. The short fiber A2 has a fineness of 0.4 to 0.9 dtex, and the passage coefficient of the short fiber A2 represented by the following formula (1) is in the range of 15 to 260. The fineness of the short fiber B is 1.1 to 20.0 dtex, the content of the short fiber A2 with respect to the whole of the mixed fiber web is 30 to 80% by mass, and the mixed fiber web. This is a method for producing a non-woven fabric for a sound absorbing material, wherein the content of the short fibers B in the whole is 20 to 70% by mass.

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 ultrafine fibers having predetermined physical properties, it is possible to provide a nonwoven fabric for a sound absorbing material which is excellent in sound absorbing performance and productivity in a low frequency region and also in excellent quality. ..

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

The nonwoven fabric for sound absorbing material of the present invention has a laminated structure of nonwoven fabric A and nonwoven fabric B. The nonwoven fabric A contains 80% by mass or more of the fibers A1 having a fineness of 0.002 to 0.3 dtex with respect to the entire nonwoven fabric A.

Since the nonwoven fabric for sound absorbing material has a nonwoven fabric A containing 80% by mass or more of fine fibers A1 having a fineness of 0.002 to 0.3 dtex with respect to the entire nonwoven fabric A, the nonwoven fabric for sound absorbing material has a large number of fine holes. It is possible to form a porous portion having. 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. Further, when the nonwoven fabric A contains the above-mentioned fine fibers A1 in an amount of 80% by mass or more with respect to the entire nonwoven fabric A, the fiber-based porous body, foam, or air layer laminated on the nonwoven fabric for sound absorbing material described later has. The contained air resonates with the non-woven fabric for sound absorbing material, and the film vibration effect of the non-woven fabric for sound absorbing material improves the sound absorbing performance especially in the low frequency region. In the present specification, the description that the sound absorption performance is excellent means that the sound absorption performance in the low frequency region is excellent.

By setting the fineness of the fiber A1 to 0.002 dtex or more, the surface reflection of sound on the surface of the nonwoven fabric A can be reduced, and the sound absorption due to the air friction between the fiber A1 contained in the nonwoven fabric A and the sound can be enhanced. .. On the other hand, by setting the fineness of the fiber A1 to 0.3 dtex or less, the sound absorption property of a particularly low frequency can be enhanced by the film vibration effect of the non-woven fabric for sound absorbing material. In the above points, the fineness of the fiber A1 is preferably 0.004 to 0.2 dtex, and more preferably 0.006 to 0.1 dtex.

Here, as the material constituting the fiber A1, a thermoplastic resin such as a polyester resin, a polyamide resin, an acrylic resin, or a polyolefin resin can be used. Among these, the fiber A1 is a fiber 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. Polyester fiber), especially a fiber made of polyethylene terephthalate resin having excellent heat resistance is preferable. Further, from the viewpoint of productivity, a fiber made of a polyolefin-based resin (polyolefin-based fiber) capable of efficiently producing the nonwoven fabric A by the melt blow method described later, particularly a fiber made of a polypropylene resin having excellent productivity is preferable. It should be noted that these thermoplastic resins may be obtained by polymerizing a plurality of types of monomers, or may contain additives such as stabilizers.

The nonwoven fabric B of the present invention contains the short fibers A2 having a fineness of 0.4 to 0.9 dtex in an amount of 30 to 80% by mass with respect to the entire nonwoven fabric B, and the staple fibers B having a fineness of 1.1 to 20.0 dtex are contained in the nonwoven fabric B. It contains 20 to 70% by mass with respect to the entire B, and the passage coefficient of the staple fiber A2 represented by 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)>
By having the above-mentioned nonwoven fabric B, the nonwoven fabric for sound absorbing material can form a porous portion having a large number of fine pores. 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. Further, when the nonwoven fabric layer B has a certain mass, the film vibration effect of the nonwoven fabric for sound absorbing material obtained by the nonwoven fabric A can be further enhanced, and the sound absorbing property of a particularly low frequency is improved.

In the non-woven fabric B as described above, the occurrence of thread breakage of the short fiber A2 and the wrapping of the short fiber A2 around the staple cloth is suppressed in the card process by a card machine or the like in the manufacturing process. By suppressing the occurrence of thread breakage of the short fiber A2 and wrapping of the short fiber A2 around the staple cloth, the productivity of the nonwoven fabric B is improved, and the productivity of the nonwoven fabric for sound absorbing material is improved. Since the short fibers A2 cut inside the non-woven fabric B are also suppressed from being generated as fiber lumps, high sound absorption performance can be obtained. Further, since the generation of the short fibers A2 cut inside the nonwoven fabric B as fiber lumps is suppressed, the quality of the nonwoven fabric B is improved, and the quality of the nonwoven fabric for sound absorbing material is also excellent. The present inventor has found that. 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 card passing coefficient of the staple fiber A2 is in the range of 15 to 260.

The nonwoven fabric B of the present invention has a feature (feature point 1) that it contains 20 to 70% by mass of short fibers B having a fineness of 1.1 to 20.0 dtex with respect to the total mass of the nonwoven fabric B. 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. As described above, the short fiber A2 having a low fineness tends to cause thread breakage in the card process, wrap around the staple cloth, and become a fiber lump inside the non-woven fabric for sound absorbing material, as compared with the short fiber B. .. On the other hand, the staple fiber B having a fineness of 1.1 to 20.0 dtex is less likely to cause the above-mentioned yarn breakage, winding, and fiber lump phenomenon.

Therefore, by containing 20% by mass or more of such short fibers B with respect to the total mass of the nonwoven fabric B, the frequency of yarn breakage, wrapping around the staple cloth, and occurrence of fiber lumps that occur in the entire nonwoven fabric B is reduced. As a result, it is presumed that the productivity and quality of the nonwoven fabric B are improved, and a nonwoven 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 nonwoven fabric B is too large, the porous portion of the nonwoven fabric B becomes coarse and large, and the sound absorbing performance when the nonwoven fabric for sound absorbing material is used as the sound absorbing material tends to deteriorate. be. Therefore, the content of the staple fibers B is 70% by mass or less with respect to the total mass of the nonwoven fabric B. In the above points, the content of the staple fibers B is preferably 25% by mass or more, more preferably 30% by mass or more, based on the total mass of the nonwoven fabric B. Further, it is preferably 60% by mass or less, and more preferably 55% by mass or less.

The fineness of the staple fiber B is 1.1 to 20.0 dtex. By setting the fineness of the staple fiber B to 20.0 dtex or less, the short fiber A2 having a small fineness does not hinder the formation of fine porous portions, and has excellent sound absorption when used as a sound absorbing material. Can be obtained. On the other hand, by setting the fineness of the staple fiber B to 1.1 dtex or more, the staple fiber A2 is uniformly dispersed inside the nonwoven fabric B, and the staple fiber A2 is generated as a fiber mass inside the nonwoven fabric B. Is suppressed, the quality of the nonwoven fabric B is improved, and the quality of the nonwoven fabric for sound absorbing material is improved. Further, since the short fibers A2 are uniformly dispersed, a porous portion having a large number of fine pores can be formed inside the nonwoven fabric B, and the sound absorbing performance when the nonwoven fabric for sound absorbing material containing the nonwoven fabric B is used as the sound absorbing material. Will be excellent. Further, it is possible to suppress thread breakage and wrapping around the staple cloth of the short fiber A2 in the card process, and as a result, it is possible to improve the productivity of the nonwoven fabric B and the productivity of the nonwoven fabric for sound absorbing material. In the above points, the fineness of the staple fiber B is preferably 1.3 to 18.0 dtex, and more preferably 1.4 to 15.0 dtex.

Next, the nonwoven fabric B of the present invention contains 30 to 80% by mass of staple fibers A2 having a fineness of 0.4 to 0.9 dtex, and the passage coefficient of the staple fibers A2 represented by the following formula (1) is It has a feature (feature point 2) that is in the range of 15 to 260.

Passing coefficient = (fineness x strength x √ elongation x √ number of crimps x √ crimp degree) / (fiber length) (Equation 1)
<Fineness (dtex), strength (cN / dtex), elongation (%), number of crimps (mountain / 25 mm), crimp degree (%), fiber length (cm)>
When the nonwoven fabric B 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 A2 having a low fineness tends to cause thread breakage in the carding process, wrap around the staple cloth, and easily form a fiber mass inside the non-woven fabric B. However, even if the staple fiber A2 has a fineness of 0.4 to 0.9 dtex, if the card passing coefficient is within the range of 15 to 260, the occurrence of yarn breakage of the staple fiber A2 in the carding process is suppressed. Will be done. That is, the non-woven fabric for a sound absorbing material containing the short fibers A2 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 A2 in the card process is suppressed, the productivity of the non-woven fabric B is improved, 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. It will be excellent. The mechanism is presumed to be as follows. Optimizing the balance between the fineness, strength, elongation, number of crimps, and crimping degree, which are the characteristics of the short fiber A2, and the fiber length (that is, the card passing coefficient of the short fiber A2 is 15 to 260). Therefore, it is considered that the thread breakage due to the friction between the short fiber A2 and the needle cloth in the card process is suppressed (this is particularly affected by the strength of the short fiber A2 and the elongation of the short fiber A2). ), It is presumed that the wrapping of the short fiber A2 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 A2). Then, in the card process, the short fibers A2 and the short fibers B are uniformly dispersed and entangled inside the non-woven fabric, and the generation of the short fibers A2 as a fiber mass is suppressed inside the non-woven fabric B (this means that it is suppressed. In particular, the number of crimps and the degree of crimp of the short fiber A2 are considered to be large), the quality of the non-woven fabric B is improved, the quality of the non-woven fabric for sound absorbing material is improved, and the short fiber A2 is inside the non-woven fabric B. A porous portion having a large number of fine pores can be formed inside the non-woven fabric B by uniformly dispersing in the non-woven fabric B, and the sound absorbing performance of the sound absorbing material using the non-woven fabric for sound absorbing material containing the non-woven fabric B becomes excellent. ..

Further, the passage coefficient of the staple fiber A2 can be made desired by adjusting the fineness, strength, elongation, number of crimps, crimp degree and fiber length of the staple fiber A2. For the above reasons, the passage coefficient of the staple fiber A2 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, crimp degree and fiber length of the staple fiber A2 can be taken is particularly limited as long as the above-mentioned passage 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 A2 is 0.4 to 0.9 dtex. By setting the fineness of the staple fiber A2 to 0.9 dtex or less, the short fiber A2 having a low fineness can form a porous portion having a large number of fine pores inside the nonwoven fabric B. 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 A2 to 0.4 dtex or more, the short fibers A2 may be uniformly dispersed inside the non-woven fabric in the card process, and the short fibers A2 may be generated as fiber lumps inside the non-woven fabric B. Since it is suppressed, the quality of the nonwoven fabric B is improved, and the quality of the nonwoven fabric for sound absorbing material is improved. Further, since the short fibers A2 are uniformly dispersed inside the nonwoven fabric, a porous portion having many fine pores can be formed inside the nonwoven fabric B, and the sound absorbing performance when used as a sound absorbing material is excellent. .. In the above points, the fineness of the staple fiber A2 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 A2 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 A2 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.

In order to further enhance the sound absorption property of the non-woven fabric for sound absorbing material, short fibers A2 having a fineness of 0.4 to 0.9 dtex and short fibers B having a fineness of 1.1 to 1.8 dtex are used, and the staple fibers are used. The ratio of the fineness of A2 to the short fiber B (the fineness of the short fiber A2 / the fineness of the short fiber B) is preferably 0.30 to 0.60. By setting the fineness of the short fiber A2 and the short fiber B in the above range, the short fiber A2 having a small fineness and the short fiber B having a finer fineness than the short fiber A2 but having a relatively low fineness make the nonwoven fabric B. It is possible to form a porous portion having a large number of fine pores inside, and it is possible to improve the sound absorption property of the non-woven fabric for sound absorbing material including the non-woven fabric B, and it is possible to obtain a sound absorbing material having particularly excellent sound absorbing property.

Further, by setting the ratio of the fineness of the short fiber A2 and the short fiber B (the fineness of the short fiber A2 / the fineness of the short fiber B) to 0.30 or more, the relative fineness of the short fiber A2 becomes smaller. It is preferable because the generation of fiber lumps in the passing step is suppressed and the decrease in sound absorption due to the increase in the relative fineness of the staple fibers B is suppressed. Further, by setting the ratio of the fineness of the short fiber A2 and the short fiber B (the fineness of the short fiber A2 / the fineness of the short fiber B) to 0.60 or less, the short fiber A2 having a relatively small fineness is relatively different from the short fiber A2. Due to the short fiber B having a high fineness, the short fiber A2 and the short fiber B are uniformly dispersed inside the non-woven fabric B in the card process, and the short fiber A2 is suppressed from being generated as a fiber mass inside the non-woven fabric B. By uniformly dispersing the fibers A2, a porous portion having many fine pores can be formed inside the non-woven fabric B, and as a result, the sound absorbing performance when the non-woven fabric for sound absorbing material containing the non-woven fabric B is used as the sound absorbing material. Will be excellent.

The tensile strength of the staple fibers A2 (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 A2 to 2.5 cN / dtex or more, yarn breakage due to friction between the short fiber A2 and the staple cloth in the card process in the manufacturing process of the non-woven fabric B is further suppressed, and as a result, the non-woven fabric is used. It is possible to further improve the productivity of B and the productivity of the nonwoven fabric for sound absorbing material including the nonwoven fabric B. In the above points, the tensile strength of the staple fiber A2 is more preferably 2.8 cN / dtex or more.

The tensile elongation of the staple fiber A2 (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 A2 to 20% or more, thread breakage due to friction between the short fiber A2 and the staple cloth in the card process is further suppressed, and the productivity of the non-woven fabric B is increased, resulting in sound absorption. The productivity of the non-woven fabric for materials can be further improved. On the other hand, by setting the tensile elongation of the short fiber A2 to 40% or less, the wrapping around the staple cloth caused by the elongation of the short fiber A2 due to the friction with the staple cloth in the card process is further reduced, and the non-woven fabric B is produced. The property is improved, and as a result, the productivity of the non-woven fabric for sound absorbing material can be further improved. In this respect, the tensile elongation of the staple fiber A2 is more preferably 22% to 35%.

The short fiber A2 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 A2 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 A2 due to the friction with the cloth, can be further reduced, and the productivity of the non-woven fabric B and the productivity of the non-woven fabric for sound absorbing material can be further improved. Further, by suppressing thread breakage and wrapping around the staple cloth due to friction, the generation of fiber lumps is suppressed, and the short fibers A2 are uniformly dispersed so that the porous portion having many fine pores is formed inside the non-woven fabric B. As a result, the sound absorbing performance when the non-woven fabric for sound absorbing material containing the non-woven fabric B is used as the sound absorbing material is excellent. Further, from the above point, the tensile strength of the staple fiber A2 is particularly preferably 6.0 cN / dtex or more.

The number of crimps of the staple fiber A2 is preferably 10.0 peaks / 25 mm or more. By setting the number of crimps of the short fibers A2 to 10.0 ridges / 25 mm or more, the short fibers A2 and the short fibers B are uniformly dispersed inside the non-woven fabric in the card process, and the short fibers A2 are inside the non-woven fabric B. Is suppressed from being generated as a fiber mass, the quality of the nonwoven fabric B is improved, and as a result, the quality of the nonwoven fabric for sound absorbing material is improved. Further, by uniformly dispersing the short fibers A2, a porous portion having a large number of fine pores can be formed inside the nonwoven fabric B, and the sound absorbing performance of the sound absorbing material using the nonwoven fabric for sound absorbing material containing the nonwoven fabric B can be improved. It will be excellent. In this respect, the number of crimps of the staple fiber A2 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 staple fibers A2 is not particularly limited, but is preferably 18.0 peaks / 25 mm or less from the viewpoint of dispersibility of the staple fibers A2.

The degree of crimping of the staple fibers A2 is preferably 12.0% or more. By setting the degree of crimp of the staple fiber A2 to 12.0%, the staple fiber A2 and the staple fiber B are uniformly dispersed in the card process, and the staple fiber A2 is generated as a fiber mass inside the nonwoven fabric B. Is suppressed, the quality of the nonwoven fabric B is improved, and as a result, the quality of the nonwoven fabric for sound absorbing material is improved. Further, since the short fibers A2 are uniformly dispersed, a porous portion having a large number of fine pores can be formed inside the nonwoven fabric B, and the sound absorbing performance when the nonwoven fabric for sound absorbing material containing the nonwoven fabric B is used as the sound absorbing material. Will be excellent. In this respect, the degree of crimping of the staple fiber A2 is more preferably 13.0% or more, and particularly preferably 14.0% or more. The upper limit of the degree of crimping of the short fibers A2 is not particularly limited, but is preferably 19.0% or less from the viewpoint of dispersibility of the short fibers A2.

The fiber length of the staple fiber A2 is preferably in the range of 2.5 to 4.5 cm. By setting the fiber length of the short fiber A2 to 4.5 cm or less, it is possible to suppress the wrapping around the staple cloth in the card process in the manufacturing process of the nonwoven fabric B, and the productivity of the nonwoven fabric B is improved, as a result. The productivity of the non-woven fabric for sound absorbing material 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, the transportability of the web to the needle punching process and the span race process described later is improved, and the productivity of the nonwoven fabric B is improved. As a result, the productivity of the non-woven fabric for sound absorbing material can be improved. In the above points, the fiber length of the staple fiber A2 is more preferably in the range of 3.0 to 4.5 cm.

The nonwoven fabric B of the present invention contains the above-mentioned short fibers A2 in an amount of 30% by mass or more based on the total mass of the nonwoven fabric B, and the short fibers A2 having a small fineness make fine pores inside the nonwoven fabric B. It is possible to form a porous portion having a large number of fibers, and when the sound passes through the voids between the fibers (that is, the porous portions), the sound is efficiently converted into heat by air friction with the fibers around the voids. Therefore, when a nonwoven fabric for a sound absorbing material containing the nonwoven fabric B is used as the sound absorbing material, excellent sound absorbing properties can be obtained. On the other hand, by setting the content of the staple fiber A2 as described above to 80% by mass or less with respect to the total mass of the nonwoven fabric B, the occurrence of yarn breakage of the staple fiber A2 generated in the carding process is extremely effective. It can be suppressed. In the above points, the content of the staple fibers A2 is preferably 40% by mass or more, more preferably 45% by mass or more, based on the total mass of the nonwoven fabric B. Further, it is preferably 75% by mass or less, and more preferably 70% by mass or less.

Here, as the material constituting the short fiber A2, 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 A2 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 when used in an engine room of an automobile or the like in a high temperature environment. Fibers (polyester-based staple fibers) are preferable, and among them, short fibers made of polyethylene terephthalate resin (polyester terephthalate staple fibers), which are particularly excellent in heat resistance, are 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 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 when used in an engine room of an automobile or the like in a high temperature environment. (Polyester-based staple fibers) are preferable, and among them, short fibers made of polyethylene terephthalate resin (polyester terephthalate staple fibers), which are particularly excellent in heat resistance, are 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 700 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. Further, since the nonwoven fabric for sound absorbing material has a certain mass, the membrane vibration effect of the nonwoven fabric A can be further enhanced, the resonance frequency can be shifted to a lower frequency region, and the sound absorbing performance in a particularly low frequency region can be enhanced. can. On the other hand, by setting the basis weight to 700 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 170 g / m ² or more, and more preferably 190 g / m ² or more. The upper limit of the basis weight is preferably 600 g / m ² or less, and more preferably 550 g / m ² or less.

The basis weight of the nonwoven fabric A of the present invention is preferably 5 g / m ² or more and 50 g / m ² or less. By setting the texture of the non-woven fabric A to 5 g / m ² or more, the air contained in the fibrous porous body, foam, or air layer laminated on the non-woven fabric for sound absorbing material described later resonates with the non-woven fabric for sound absorbing material. The film vibration effect of the non-woven fabric for sound absorbing material is particularly preferable because the sound absorbing property of low frequency is improved. On the other hand, when the basis weight is 50 g / m ² or less, the productivity of the nonwoven fabric A can be increased, and as a result, the productivity of the nonwoven fabric for sound absorbing material is increased, which is preferable.

The basis weight of the nonwoven fabric B of the present invention is preferably 100 g / m ² or more and 650 g / m ² or less. By setting the basis weight to 100 g / m ² or more, the sound absorption performance due to air friction can be improved. Further, since the nonwoven fabric B has a constant mass, the film vibration effect of the nonwoven fabric A can be further enhanced, and the sound absorption performance in a particularly low frequency region can be enhanced. On the other hand, by setting the basis weight to 450 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 120 g / m ² or more, and more preferably 140 g / m ² or more. The upper limit of the basis weight is preferably 550 g / m ² or less, and more preferably 500 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 reducing the thickness to 4.0 mm or less, the non-woven fabric for sound absorbing material has a more dense structure, and fine porous portions are formed by the fibers A1 and the short fibers A2, and the sound is converted into heat by air friction. 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. Furthermore, by reducing the thickness of the non-woven fabric for sound absorbing material to a certain thickness or less, the non-woven fabric becomes flexible, the film vibration effect of the non-woven fabric for sound absorbing material can be further enhanced, and the sound absorbing performance in a particularly low frequency region can be enhanced. can. 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 non-woven fabric based on the JIS L1913: 1998 6.1.2 A method.

Further, the non-woven fabric for sound absorbing material has a basis weight of 150 g / m ² or more and 700 g / m ² or less, and the thickness of the non-woven fabric for sound absorbing material is 0.6 mm or more and 4.0 mm or less. preferable. The basis weight of the non-woven fabric for sound absorbing material is in the above range, and the thickness of the non-woven fabric for sound absorbing material is also in the above range, so that the sound absorbing performance is further improved.

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 parts are formed by fibers A1 and short fibers A2, and conversion of sound into heat by air friction is performed. 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. Further, on the other hand, by setting the density to 0.40 g / cm ³ or less, a porous portion having a sufficient size is formed in the nonwoven 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 more than 0 μm and less than 5 μm are 5 to 100%. By having such a fine pore size distribution, it is possible to make the conversion of sound into heat by air friction more efficient, and as a result, the sound absorption when the non-woven fabric for sound absorbing material is used as the sound absorbing material. The performance will be better. Further, the film vibration effect of the non-woven fabric for sound absorbing material can be further enhanced, and the sound absorbing performance in a particularly low frequency region can be enhanced. In the above points, the number of pores having a diameter of more than 0 μm and less than 10 μm is preferably 10 to 100%, and more preferably 15 to 100% of the pores having a diameter of more than 0 μm and less than 10 μm. 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 0.1 to 15 cm ³ / cm ² / s. When the air permeability of the non-woven fabric for sound absorbing material is 0.1 cm ³ / cm ² / s or more, the surface reflection of sound on the surface of the non-woven fabric for sound absorbing material is suppressed, and the sound absorbing performance of the non-woven fabric for sound absorbing material due to air friction is improved. It is preferable because it is excellent. From the above viewpoint, the air permeability is preferably 0.2 cm ³ / cm ² / s or more, and particularly preferably 0.4 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 15 cm ³ / cm ² / s or less because the sound absorbing performance due to air friction is improved. Further, the film vibration effect of the non-woven fabric for sound absorbing material can be further enhanced, and the sound absorbing performance in a particularly low frequency region can be enhanced. From the above viewpoint, the air permeability is preferably 12 cm ³ / cm ² / s or less, and more preferably 10 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 for a sound absorbing material of the present invention has the following steps.

(Manufacturing of non-woven fabric A)
(A) A step of obtaining a nonwoven fabric A containing 80% by mass or more of fibers A1 having a fineness of 0.002 to 0.3 dtex with respect to the entire nonwoven fabric A by a melt blow method.

(Manufacturing of non-woven fabric B)
(B) Step of opening the short fibers A2 and B to obtain a mixed fiber web of the short fibers A2 and the short fiber B (c) The mixed fiber web passes through the water jet punch nozzle three times or more, and the non-woven fabric is used. The process of obtaining B.

(Manufacturing of non-woven fabric for sound absorbing material)
(D) A step of laminating the nonwoven fabric A and the nonwoven fabric B to obtain a nonwoven fabric for a sound absorbing material.

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

(Manufacturing of non-woven fabric A)
First, a step of (a) obtaining a nonwoven fabric A by the melt blow method will be described.

In the melt blow process, the thermoplastic resin is supplied to the heated extruder, melt extruded, and the molten resin is discharged from the nozzle using the melt blow mouthpiece, and heated air is blown onto the discharged molten resin. It is possible to obtain a nonwoven fabric A containing 80% by mass or more of fibers A1 having a fineness of 0.002 to 0.3 dtex with respect to the entire nonwoven fabric A.

Regarding the non-woven fabric A, by roll-pressing the non-woven fabric A using a calendar processing machine or the like, the non-woven fabric A can be densified to reduce the air permeability of the non-woven fabric for sound absorbing material and improve the sound absorbing property in the low frequency region. can.

(Manufacturing of non-woven fabric B)
Next, (b) a step of obtaining a mixed fiber web will be described. First, a step (opener step) for opening the staple fibers A2 and the staple fibers B included in the above steps will be described.

In the opener step, the short fibers A2 and the short fibers B (hereinafter, also referred to as each short fiber) are weighed so that the content of the short fibers A2 and the content of the short fibers B in the non-woven fabric for sound absorbing material are desired. , Air, etc. are used to sufficiently open each staple fiber and mix it.

Next, a step (card step) of forming a web-like mixture of the staple fibers A2 and the staple fibers B 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.

Next, a step (c) of entwining the short fibers A2 and the short fibers B contained in the mixed fiber web with a needle or a water stream to obtain a nonwoven fabric B will be described (entanglement step).

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. This method is preferably adopted because the nonwoven fabric B can be densified as compared with the chemical bond method or the like, and a nonwoven fabric for a sound absorbing material having a preferable thickness and density can be easily obtained.

When each short fiber is entangled by the needle punch method, it is preferable that the staple density is 200 fibers / 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 nonwoven fabric B can be densified, and the sound absorbing performance when the nonwoven fabric for sound absorbing material containing the nonwoven fabric B is used as the sound absorbing material 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 B can be densified, and the sound-absorbing performance when the non-woven fabric for a sound-absorbing material containing the non-woven fabric B can be used as the sound-absorbing material is preferable. Further, it is preferable to pass the nonwoven fabric B three times or more because the nonwoven fabric B can be densified in the same manner as described above and the sound absorbing performance when the nonwoven fabric for a sound absorbing material containing the nonwoven fabric B is used as the sound absorbing material can be improved. 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 punching method can efficiently entangle short fibers having a fine fineness without thread breakage in the entanglement step, and the nonwoven fabric B of the present invention containing the staple fibers A2 having a fineness of 0.4 to 0.9 dtex. Can be suitably used for manufacturing.

Finally, (d) a step of laminating the nonwoven fabric A and the nonwoven fabric B to obtain a nonwoven fabric for a sound absorbing material will be described. As a method of laminating and integrating the nonwoven fabric A and the nonwoven fabric B, a low melting point copolymer resin such as polyolefin, polyamide or polyester is used, and the powder made of the low melting point copolymer resin is sprayed between the nonwoven fabric A and the nonwoven fabric B. Then, a method of melting the resin with a heating roll and adhering the resin can be used.

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 above-mentioned 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 nonwoven fabric for sound absorbing material 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. Further, with the above configuration, the air contained in the fibrous porous body, foam, or air layer resonates with the non-woven fabric for sound absorbing material, and the film vibration effect of the non-woven fabric for sound absorbing material causes a particularly low frequency. Sound absorption is improved. The thickness of the layered material can be measured by using a metal ruler to measure the length of the side surface of the layered material in the thickness direction.

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

(Measuring method)
(1) Fibers and content of each fiber constituting the non-woven fabric for sound absorbing material Non-woven fabric A and non-woven fabric B are separated, and JIS L 1030-1: 2006 "Mixing rate test method for textile products-Part 1: Fibers" is used for each non-woven fabric. Based on "Identification" and JIS L 1030-2: 2005 "Test method for mixing ratio of textile products-Part 2: Fiber mixing ratio", the positive amount mixing ratio (mass ratio of each fiber in the standard state) was measured. This was defined as the content (% by mass) of the fibers constituting the non-woven fabric for sound absorbing material. Thereby, the fiber material constituting the nonwoven fabric for sound absorbing material (woven fabric A and nonwoven fabric B) and its content (mass%) were specified.

(2) Fineness and content of 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 each of the residual non-woven fabrics of the non-woven fabric A and the non-woven fabric B 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. Then, a cross-sectional photograph with a magnification of 1,000 times 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 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 × fiber specific density / 100 (2)
Regarding the non-woven fabric A, for fibers having a fineness of 0.002 to 0.3 dtex, the content of the fibers having a fineness of 0.002 to 0.3 dtex based on the fineness of each section, the number of fibers in each section, and the specific gravity of the fiber material. (Mass%) was calculated by the following formula (3).

Content (% by mass) of fibers having a fineness of 0.002 to 0.3 dtex = ((Fibers of fibers having a fineness of 0.002 to 0.3 dtex (dtex) x number of fibers per section (lines)) ) / (Fiberity (dtex) for each section of fiber other than 0.002 to 0.3 dtex x number of fibers (line) for each section) x 100 (3)
Regarding the non-woven fabric B, for fibers having a fineness of 0.4 to 0.9 dtex, the content of the fibers having a fineness of 0.4 to 0.9 dtex based on the fineness of each section, the number of fibers in each section, and the specific gravity of the fiber material. (Mass%) was calculated by the following formula (4).

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 (4)
For the nonwoven fabric B, the content (% by mass) of the fibers having a fineness of 1.1 to 20.0 dtex was determined in the same manner.

When there are a plurality of fiber materials of the non-woven fabric A or the non-woven fabric B constituting the non-woven fabric for sound absorbing material, the above-mentioned fineness and content are measured for each non-woven fabric using the residual nonwoven fabric in the dissolving method. , The fineness and content of the fibers constituting the non-woven fabric for sound absorbing material were determined.

(3) Fiber length of short fibers constituting the non-woven fabric B 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 B Based on JIS L 1015 (1999) 8.7.1, both ends are loosely stretched one by one with a space distance of 20 mm and a staple. Adhere to a piece of paper with an adhesive and fix it, and make one sample for each category. 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 staple fibers constituting non-woven fabric B Number of crimps of fibers constituting non-woven fabric according to the method of JIS L 1015-8-12-1, 2 (2010 revised edition) Was measured.

(6) Degree of crimp of short fibers constituting non-woven fabric B Measure the crimping rate (%) of fibers constituting non-woven fabric according to the method of JIS L 1015-8-12-1, 2 (2010 revised edition). This was defined as the degree of crimping (%) of the fiber.

(7) Card process pass rate (productivity and quality) of non-woven fabric B
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 passing rate, the better the card process passing rate.

Card process pass rate (%) = web mass (g) / input amount (g) x 100
Moreover, the appearance of the obtained nonwoven fabric B was visually observed. Three 300 mm × 300 mm test pieces were collected from the sample of the non-woven fabric B using a steel ruler and a razor blade, the number of fiber lumps was counted, and the number was 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. Regarding the basis weights of the nonwoven fabric A and the nonwoven fabric B, the nonwoven fabric A and the nonwoven fabric B were separated and the basis weight was measured in the same manner.
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 (m ² ) of the test piece of the non-woven fabric for sound absorbing material.

(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 calculated by the following formula.

Density of non-woven fabric for sound absorbing material (g / cm ³ ) = Metsuke 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 frequency 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 (%) was more than 0 and less than 5 μm, and 5 μm or more and less than 10 μm.

(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 (%).

(Example 1)
(Nonwoven fabric A)
Polypropylene (PP) resin was supplied to an extruder, melted at a temperature of 260 ° C., and extruded from a melt blow mouthpiece. At this time, heated air at 300 ° C. and 0.09 MPa was blown toward the discharged resin fluid and laminated on a wire mesh depositing device at a distance of 20 cm from the base, and the fineness was 0.002 to 0.3 dtex section. A non-woven fabric A having an average fineness of 0.017 dtex, a content of fiber A1 of 99% by mass, and a basis weight of 20 g / m ² was obtained.

(Nonwoven fabric B)
As a staple fiber A2, 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. 50% by mass of polyethylene terephthalate (PET) staples, 50% by mass of polyethylene terephthalate (PET) staples having a fineness of 1.60 dtex as short fibers B and a fiber length of 5.1 cm were used, and each short fiber was subjected to an opener process. After that, it was subjected to a card process (cylinder rotation speed 300 rpm, doffer speed 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. The stapled fabric B was dried at 120 ° C. to obtain a non-woven fabric B having a fineness ratio of 0.35 between the staple fibers A2 and the staple fibers B and a grain size of 200 g / m ² .

(Non-woven fabric for sound absorbing material)
5 g / m ² of low melting point powder made of ethylene-vinyl acetate copolymer resin having a melting point of 83 ° C. is sprayed on the upper surface of the nonwoven fabric B, and the nonwoven fabric A is laminated on the upper surface of the nonwoven fabric B and bonded with a heating roll at 120 ° C. A nonwoven fabric for a sound absorbing material having a grain size of 225 g / m ² , a thickness of 1.1 mm, and a nonwoven fabric density of 0.205 g / cm ³ was obtained.

In the non-woven fabric for sound absorbing material of Example 1, there was no cotton drop or wrapping around the needle cloth due to thread breakage in the card process of the non-woven fabric B, and the card process passability was as good as 97%. In addition, the dispersion of each staple fiber was good, no fiber lumps were generated, and the quality was good.

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

(Example 2)
(Nonwoven fabric A)
The non-woven fabric A of Example 1 was used.

(Nonwoven fabric B)
Same as Example 1 except that the short fibers A2 of Example 1 were used as the short fibers A2 and the short fibers B of Example 1 were used as the short fibers B, and the contents were changed to 35% by mass and 65% by mass, respectively. The non-woven fabric B having a fineness ratio of 0.35 between the staple fibers A2 and the staple fibers B and a grain size of 200 g / m ² was obtained.

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 1.2 mm, and a nonwoven fabric density of 0.188 g / cm ³ .

In the non-woven fabric for sound absorbing material of Example 2, there was no cotton drop or wrapping around the needle cloth due to thread breakage in the card process of the non-woven fabric B, and the card process passability was as good as 97%. In addition, the dispersion of each staple fiber was good, no fiber lumps were generated, and the quality was good.

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

(Example 3)
(Nonwoven fabric A)
The non-woven fabric A of Example 1 was used.

(Nonwoven fabric B)
Same as Example 1 except that the short fibers A2 of Example 1 were used as the short fibers A2 and the short fibers B of Example 1 were used as the short fibers B, and the contents were changed to 65% by mass and 35% by mass, respectively. The non-woven fabric B having a fineness ratio of 0.35 between the staple fibers A2 and the staple fibers B and a grain size of 200 g / m ² was obtained.

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 1.1 mm, and a nonwoven fabric density of 0.205 g / cm ³ .

The non-woven fabric for sound absorbing material of Example 3 had less cotton drop due to thread breakage in the card process of the non-woven fabric B and wrapping around the needle cloth, and the card process passability was relatively good at 94%. 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 of the obtained laminated nonwoven fabric for sound absorbing material was high.

(Example 4)
(Nonwoven fabric A)
The non-woven fabric A of Example 1 was used.

(Nonwoven fabric B)
Same as Example 1 except that the short fibers A2 of Example 1 were used as the short fibers A2 and the short fibers B of Example 1 were used as the short fibers B, and the contents were changed to 75% by mass and 25% by mass, respectively. The non-woven fabric B having a fineness ratio of 0.35 between the staple fibers A2 and the staple fibers B and a grain size of 200 g / m ² was obtained.

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 1.1 mm, and a nonwoven fabric density of 0.205 g / cm ³ .

The non-woven fabric for sound absorbing material of Example 4 had less cotton drop due to thread breakage in the card process of the non-woven fabric B and wrapping around the needle cloth, and the card process passability was relatively good at 92%. 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 of the obtained laminated nonwoven fabric for sound absorbing material was high.

(Example 5)
(Nonwoven fabric A)
Polypropylene (PP) resin was supplied to an extruder, melted at a temperature of 240 ° C., and extruded from a melt blow mouthpiece. At this time, heated air at 300 ° C. and 0.06 MPa was blown toward the discharged resin fluid and laminated on a wire mesh depositing device at a distance of 20 cm from the base, and the fineness was 0.002 to 0.3 dtex section. A non-woven fabric A having an average fineness of 0.142 dtex, a content of fiber A1 of 90% by mass, and a basis weight of 20 g / m ² was obtained.

(Nonwoven fabric B)
The non-woven fabric B of Example 1 was used.

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 1.2 mm, and a nonwoven fabric density of 0.188 g / cm ³ .

In the non-woven fabric for sound absorbing material of Example 5, there was no cotton drop or wrapping around the needle cloth due to thread breakage in the card process of the non-woven fabric B, and the card process passability was as good as 97%. In addition, the dispersion of each staple fiber was good, no fiber lumps were generated, and the quality was good.

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

(Example 6)
(Nonwoven fabric A)
Using the nonwoven fabric A of Example 1, using a calender processing machine having a metal roll and a paper roll, the metal roll is under the conditions of a metal roll temperature of 90 ° C., a paper roll temperature of 60 ° C., a linear pressure of 600 N / cm, and a speed of 2 m / min. / Roll-pressed between paper rolls to obtain a non-woven fabric A having an average fineness of 0.018 dtex in the fineness section of 0.002 to 0.3 dtex, a fiber A1 content of 99% by mass, and a grain size of 20 g / m ² .

(Nonwoven fabric B)
The non-woven fabric B of Example 1 was used.

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 1.0 mm, and a nonwoven fabric density of 0.225 g / cm ³ .

In the non-woven fabric for sound absorbing material of Example 6, there was no cotton drop or wrapping around the needle cloth due to thread breakage in the card process of the non-woven fabric B, and the card process passability was as good as 97%. In addition, the dispersion of each staple fiber was good, no fiber lumps were generated, and the quality was good.

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

(Example 7)
(Nonwoven fabric A)
The non-woven fabric A of Example 1 was used.

(Nonwoven fabric B)
As a staple fiber A2, 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) staple fibers and 50% by mass of the short fibers B of Example 1 were used as the short fibers B, and the short fibers were shorter than the short fibers A2. A non-woven fabric B having a fiber B fineness ratio of 0.35 and a texture of 200 g / m ² was obtained.

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 1.2 mm, and a nonwoven fabric density of 0.188 g / cm ³ .

The non-woven fabric for sound absorbing material of Example 7 had less cotton drop due to thread breakage in the card process of the non-woven fabric B 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 of the obtained laminated nonwoven fabric for sound absorbing material was high.

(Example 8)
(Nonwoven fabric A)
The non-woven fabric A of Example 1 was used.

(Nonwoven fabric B)
As a staple fiber A2, 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) staple fibers and 50% by mass of the short fibers B of Example 1 were used as the short fibers B, and the short fibers were shorter than the short fibers A2. A non-woven fabric B having a fiber B fineness ratio of 0.35 and a texture of 200 g / m ² was obtained.

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 1.2 mm, and a nonwoven fabric density of 0.188 g / cm ³ .

The non-woven fabric for sound absorbing material of Example 8 had less cotton drop due to thread breakage in the card process of the non-woven fabric B and wrapping around the needle cloth, and the card process passability was relatively good at 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 laminated nonwoven fabric for sound absorbing material was high.

(Example 9)
(Nonwoven fabric A)
The non-woven fabric A of Example 1 was used.

(Nonwoven fabric B)
As a staple fiber A2, 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) staple fibers and 50% by mass of the short fibers B of Example 1 were used as the short fibers B, and the short fibers were shorter than the short fibers A2. A non-woven fabric B having a fiber B fineness ratio of 0.36 and a texture of 200 g / m ² was obtained.

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 1.1 mm, and a nonwoven fabric density of 0.205 g / cm ³ .

In the non-woven fabric for sound absorbing material of Example 9, there was no cotton drop or wrapping around the needle cloth due to thread breakage in the card process of the non-woven fabric B, and the card process passability was as good as 98%. In addition, the dispersion of each staple fiber was good, no fiber lumps were generated, and the quality was also good.

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

(Example 10)
(Nonwoven fabric A)
The non-woven fabric A of Example 1 was used.

(Nonwoven fabric B)
Examples except that 50% by mass of the short fiber A2 of Example 1 was used as the short fiber A2 and 50% by mass of polyethylene terephthalate (PET) short fibers having a fineness of 2.20 dtex and a fiber length of 5.1 cm were used as the short fiber B. The treatment was carried out under the same steps and conditions as in No. 1, to obtain a nonwoven fabric B having a fineness ratio of 0.25 between the staple fibers A2 and the staple fibers B and a grain size of 200 g / m ² .

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 1.1 mm, and a nonwoven fabric density of 0.205 g / cm ³ .

In the non-woven fabric for sound absorbing material of Example 10, there was no cotton drop or wrapping around the needle cloth due to thread breakage in the card process of the non-woven fabric B, and the card process passability was as good as 98%. In addition, the dispersion of each staple fiber was good, no fiber lumps were generated, and the quality was also good.

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

(Example 11)
(Nonwoven fabric A)
The non-woven fabric A of Example 1 was used.

(Nonwoven fabric B)
As a staple fiber A2, the fineness is 0.85 dtex, the fiber length is 5.1 cm, the strength is 5.3 cN / dtex, the elongation is 25%, the number of crimps is 13.3 peaks / 25 mm, the crimp degree is 15.4%, and the passage coefficient is 63. Same as Example 1 except that 50% by mass of polyethylene terephthalate (PET) staple fibers and 50% by mass of polyethylene terephthalate (PET) staple fibers having a fineness of 1.21 dtex and a fiber length of 5.1 cm were used as short fibers B. Treatment was performed according to the process and conditions to obtain a non-woven fabric B having a fineness ratio of 0.70 between the staple fibers A2 and the staple fibers B and a grain size of 200 g / m ² .

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 1.1 mm, and a nonwoven fabric density of 0.205 g / cm ³ .

The non-woven fabric for sound absorbing material of Example 11 had less cotton drop due to thread breakage in the card process of the non-woven fabric B and wrapping around the needle cloth, and the card process passability was relatively good at 94%. 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 of the obtained laminated nonwoven fabric for sound absorbing material was high.

(Example 12)
(Nonwoven fabric A)
The non-woven fabric A of Example 1 was used.

(Nonwoven fabric B)
50% by mass of the short fiber A2 of Example 1 was used as the short fiber A2, and 50% by mass of the short fiber B of Example 1 was used as the short fiber B. The treatment was carried out under the same conditions as in Example 1 to obtain a non-woven fabric B having a fineness ratio of 0.35 between the staple fibers A2 and the staple fibers B and a grain size of 140 g / m ² .

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 165 g / m ² , a thickness of 0.9 mm, and a nonwoven fabric density of 0.183 g / cm ³ .

In the non-woven fabric for sound absorbing material of Example 12, there was no cotton drop or wrapping around the needle cloth due to thread breakage in the card process of the non-woven fabric B, and the card process passability was as good as 97%. In addition, the dispersion of each staple fiber was good, no fiber lumps were generated, and the quality was also good.

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

(Example 13)
(Nonwoven fabric A)
The non-woven fabric A of Example 1 was used.

(Nonwoven fabric B)
50% by mass of the short fiber A2 of Example 1 was used as the short fiber A2, and 50% by mass of the short fiber B of Example 1 was used as the short fiber B. The upper surface was changed to 8.0 MPa, the upper surface was 10.0 MPa, the lower surface was 11.0 MPa, the upper surface was 11.0 MPa, and the lower surface was 11.0 MPa. A non-woven fabric B having a fiber B fineness ratio of 0.35 and a texture of 200 g / m ² was obtained.

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 4.1 mm, and a nonwoven fabric density of 0.055 g / cm ³ .

In the non-woven fabric for sound absorbing material of Example 13, there was no cotton drop or wrapping around the needle cloth due to thread breakage in the card process of the non-woven fabric B, and the card process passability was as good as 97%. In addition, the dispersion of each staple fiber was good, no fiber lumps were generated, and the quality was also good.

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

(Example 14)
(Nonwoven fabric A)
The non-woven fabric A of Example 1 was used.

(Nonwoven fabric B)
As a staple fiber A2, 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 short fibers B of Example 1 were used as the short fibers B, and the fineness of the short fibers A2 and the short fibers B was increased. A non-woven fiber B having a ratio of 0.36 and a texture of 200 g / m ² was obtained.

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 1.1 mm, and a nonwoven fabric density of 0.205 g / cm ³ .

In the non-woven fabric for sound absorbing material of Example 14, there was no cotton drop or wrapping around the needle cloth due to thread breakage in the card process of the non-woven fabric B, and the card process passability was as good as 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 of the obtained laminated nonwoven fabric for sound absorbing material was relatively high.

(Comparative Example 1)
(Nonwoven fabric A)
The non-woven fabric A of Example 1 was used.

(Nonwoven fabric B)
Same as Example 1 except that the short fibers A2 of Example 1 were used as the short fibers A2 and the short fibers B of Example 1 were used as the short fibers B, and the contents were changed to 20% by mass and 80% by mass, respectively. The non-woven fabric B having a fineness ratio of 0.35 between the staple fibers A2 and the staple fibers B and a grain size of 200 g / m ² was obtained.

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 1.2 mm, and a nonwoven fabric density of 0.188 g / cm ³ .

The non-woven fabric for sound absorbing material of Comparative Example 1 had no cotton drop due to thread breakage in the card process of the non-woven fabric B or wrapping around the needle cloth, and the card process passability was as good as 98%. In addition, the dispersion of each staple fiber was good, no fiber lumps were generated, and the quality was also good.

The low frequency sound absorption coefficient of the obtained laminated nonwoven fabric for sound absorbing material was low.

(Comparative Example 2)
(Nonwoven fabric A)
The non-woven fabric A of Example 1 was used.

(Nonwoven fabric B)
Same as Example 1 except that the short fibers A of Example 1 were used as the short fibers A2 and the short fibers B of Example 1 were used as the short fibers B, and the contents were changed to 90% by mass and 10% by mass, respectively. The non-woven fabric B having a fineness ratio of 0.35 between the staple fibers A and the staple fibers B and a grain size of 200 g / m ² was obtained.

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 1.1 mm, and a nonwoven fabric density of 0.205 g / cm ³ .

In the non-woven fabric for sound absorbing material of Comparative Example 2, the non-woven fabric B was often dropped due to thread breakage in the card process and wrapped around the needle cloth, and the card process passability was inferior to 70%. 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 of the obtained laminated nonwoven fabric for sound absorbing material was low.

(Comparative Example 3)
(Nonwoven fabric A)
Polypropylene (PP) resin was supplied to an extruder, melted at a temperature of 220 ° C., and extruded from a melt blow cap. At this time, heated air at 300 ° C. and 0.04 MPa was blown toward the discharged resin fluid and laminated on a wire mesh depositing device at a distance of 20 cm from the base, and the fineness was 0.002 to 0.3 dtex section. A non-woven fabric A having an average fineness of 0.307 dtex, a content of fiber A1 of 46% by mass, and a basis weight of 20 g / m ² was obtained.

(Nonwoven fabric B)
The non-woven fabric B of Example 1 was used.

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 1.2 mm, and a nonwoven fabric density of 0.188 g / cm ³ .

The non-woven fabric for sound absorbing material of Comparative Example 3 had no cotton drop or wrapping around the needle cloth due to thread breakage in the card process of the non-woven fabric B, and the card process passability was as good as 97%. In addition, the dispersion of each staple fiber was good, no fiber lumps were generated, and the quality was good.

The low frequency sound absorption coefficient of the obtained laminated nonwoven fabric for sound absorbing material was low.

(Comparative Example 4)
(Nonwoven fabric A)
The non-woven fabric A of Example 1 was used.

(Nonwoven fabric B)
As a staple fiber A2, 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 33. Treatment was performed under the same steps and conditions as in Example 1 except that 50% by mass of polyethylene terephthalate (PET) staple fibers and 50% by mass of the short fibers B of Example 1 were used as the short fibers B, and the short fibers were shorter than the short fibers A2. A non-woven fabric B having a fiber B fineness ratio of 0.21 and a texture of 200 g / m ² was obtained.

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 1.2 mm, and a nonwoven fabric density of 0.188 g / cm ³ .

In the non-woven fabric for sound absorbing material of Comparative Example 4, the non-woven fabric B was often dropped due to thread breakage in the card process and wrapped around the needle cloth, and the card process passability was as poor as 75%. 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 of the obtained laminated nonwoven fabric for sound absorbing material was low.

(Comparative Example 5)
(Nonwoven fabric A)
The non-woven fabric A of Example 1 was used.

(Nonwoven fabric B)
As a staple fiber A2, 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 is 15.4%, and the passage coefficient is 97. Treatment was performed under the same steps and conditions as in Example 1 except that 50% by mass of polyethylene terephthalate (PET) staple fibers and 50% by mass of the short fibers B of Example 1 were used as the short fibers B, and the short fibers were shorter than the short fibers A2. A non-woven fabric B having a fiber B fineness ratio of 0.61 and a texture of 200 g / m ² was obtained.

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 1.2 mm, and a nonwoven fabric density of 0.188 g / cm ³ .

The non-woven fabric for sound absorbing material of Comparative Example 5 had no cotton drop or wrapping around the needle cloth due to thread breakage in the card process of the non-woven fabric B, and the card process passability was as good as 97%. In addition, the dispersion of each staple fiber was good, no fiber lumps were generated, and the quality was good.

The low frequency sound absorption coefficient of the obtained laminated nonwoven fabric for sound absorbing material was low.

(Comparative Example 6)
(Nonwoven fabric A)
The non-woven fabric A of Example 1 was used.

(Nonwoven fabric B)
As a staple fiber A2, 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. Treatment was performed under the same steps and conditions as in Example 1 except that 50% by mass of polyethylene terephthalate (PET) staple fibers and 50% by mass of the short fibers B of Example 1 were used as the short fibers B, and the short fibers were shorter than the short fibers A2. A non-woven fabric B having a fiber B fineness ratio of 0.34 and a texture of 200 g / m ² was obtained.

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 1.2 mm, and a nonwoven fabric density of 0.188 g / cm ³ .

In the non-woven fabric for sound absorbing material of Comparative Example 6, the non-woven fabric B was often dropped due to thread breakage in the card process and wrapped around the needle cloth, and the card process passability was as poor as 72%. 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 of the obtained laminated nonwoven fabric for sound absorbing material was low.

(Comparative Example 7)
(Nonwoven fabric A)
The non-woven fabric A of Example 1 was used.

(Nonwoven fabric B)
As a staple fiber A2, 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 ridges / 25 mm, the crimp degree is 4.5%, and the passage coefficient is 14. Treatment was performed under the same steps and conditions as in Example 1 except that 50% by mass of polyethylene terephthalate (PET) staple fibers and 50% by mass of the short fibers B of Example 1 were used as the short fibers B, and the short fibers were shorter than the short fibers A2. A non-woven fabric B having a fiber B fineness ratio of 0.35 and a texture of 200 g / m ² was obtained.

(Non-woven fabric for sound absorbing material)
The nonwoven fabric A and the nonwoven fabric B were bonded together by the same method as in Example 1 to obtain a nonwoven fabric for sound absorbing material having a basis weight of 225 g / m ² , a thickness of 1.2 mm, and a nonwoven fabric density of 0.188 g / cm ³ .

In the non-woven fabric for sound absorbing material of Comparative Example 6, the non-woven fabric B was often dropped due to thread breakage in the card process and wrapped around the needle cloth, and the card process passability was as poor as 76%. 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 of the obtained laminated nonwoven fabric for sound absorbing material was 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 sound absorbing material of the present invention is particularly suitable as a sound absorbing material for automobiles and the like because it is excellent in sound absorbing performance in a low frequency region, excellent in productivity, and excellent in quality.

Claims (8)

It has a laminated structure of non-woven fabric A and non-woven fabric B, and has a laminated structure.
The nonwoven fabric A contains fibers A1 having a fineness of 0.002 to 0.3 dtex in an amount of 80% by mass or more with respect to the entire nonwoven fabric A.
The nonwoven fabric B contains 30 to 80% by mass of short fibers A2 having a fineness of 0.4 to 0.9 dtex with respect to the entire nonwoven fabric B.
The nonwoven fabric B contains 20 to 70% by mass of short fibers B having a fineness of 1.1 to 20.0 dtex with respect to the entire nonwoven fabric B.
A non-woven fabric for a sound absorbing material, wherein the passing coefficient of the staple fiber A2 represented by 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 700 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 A2 is a polyester-based staple fiber. The nonwoven fabric for a sound absorbing material according to any one of claims 1 to 4, wherein the staple fiber A2 has a tensile strength of 5 cN / dtex or more and the staple fiber A2 has a tensile elongation of 20 to 35%. The fineness of the short fiber A2 is 0.4 to 0.9 dtex, the fineness of the short fiber B is 1.1 to 1.8 dtex, and the ratio of the fineness of the short fiber A2 to the short fiber B (short). The nonwoven fabric for a sound absorbing material according to any one of claims 1 to 5, wherein the fineness of the fiber A2 / the fineness of the staple fiber B) is 0.30 to 0.60. The nonwoven fabric for sound absorbing material according to any one of claims 1 to 6.
It has a fibrous porous body, a foam, or a layered material composed of an air layer.
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 obtaining a nonwoven fabric A containing 80% by mass or more of fibers A1 having a fineness of 0.002 to 0.3 dtex with respect to the entire nonwoven fabric A by a melt blow method.
A step of subjecting the short fibers A2 and the short fibers B to a fiber opening treatment to obtain a mixed fiber web of the short fibers A2 and the short fibers B,
The step of obtaining the nonwoven fabric B by passing the mixed fiber web through the water jet punch nozzle three times or more.
It has a step of laminating the nonwoven fabric A and the nonwoven fabric B.
The fineness of the staple fiber A2 is 0.4 to 0.9 dtex, and the staple fiber A2 has a fineness of 0.4 to 0.9 dtex.
The passage coefficient of the staple fiber A2 represented by the following formula (1) is in the range of 15 to 260.
The fineness of the staple fiber B is 1.1 to 20.0 dtex, and the staple fiber B has a fineness of 1.1 to 20.0 dtex.
The content of the staple fiber A2 with respect to the entire mixed fiber web is 30 to 80% by mass.
A method for producing a nonwoven fabric for a sound absorbing material, wherein the content of the staple fibers B in the entire mixed fiber web is 20 to 70% by mass.
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)>