JP6353715B2 - Non-woven sound absorbing material - Google Patents

Description

  The present invention relates to a nonwoven fabric sound absorbing material. More specifically, the present invention relates to a nonwoven fabric sound absorbing material composed of long fibers.

Sound absorbing materials (also called soundproofing materials) are used in various fields such as building materials, vehicle materials, and acoustic materials. Conventionally, sound absorbing materials using polyester fibers, polypropylene fibers, and the like are known. For example, Patent Document 1 proposes a soundproof material made of aliphatic polyester, aromatic polyester, and polypropylene fiber. Patent Document 2 proposes a soundproof sheet material using a melt blown ultrafine fiber nonwoven fabric having a density of 0.013 to 0.05 g / cm ³ . Patent Document 3 proposes a nonwoven web in which melt blown ultrafine fibers and opened short fibers are combined.

Special table 2012-522147 gazette JP 53-41577 A JP 2006-506551 A

  The conventional products proposed in Patent Documents 1 to 3 are fibrous webs made of ultrafine fibers and staple fibers having crimps made by spinning by a melt blown method. In general, the nonwoven fabric for sound absorbing material is cut into a predetermined size and used. However, in order to increase productivity, two or more sheets are overlapped and cut and cut at a time. However, since the cut portions of the sound absorbing materials described in Patent Documents 1 to 3 have been pressed, there has been a problem that they must be punched one by one. In addition, there is a problem in sound absorption, the cost is high, and these improvements have been demanded.

  In order to solve the above-mentioned conventional problems, the present invention provides a sound-absorbing material that has a high sound-absorbing property, that does not cause the cut portion to be pressure-bonded when cut repeatedly, and that is inexpensive.

The present invention relates to a nonwoven acoustical material composed of long fibers, the long fibers are mixed Nde contains fine fibers having a relatively fineness and thick relatively fineness fibers, fineness of the thick fibers the distribution center, the Ri fine fiber Ah least twice the fineness distribution center, said a thin fiber and the thick fraction of the fiber weight ratio, thin fibers: thick fibers = 80 to 30: 20 to 70, wherein the non-woven fabric A nonwoven fabric sound-absorbing material , characterized in that a spunbonded nonwoven fabric is laminated on at least one of the main surfaces, and is integrated with melt holes in the thickness direction by pin sonic processing .

  The present invention is composed of long fibers, the long fibers include relatively thick fibers and relatively thin fibers, and the fine fiber distribution center is 2 of the fine fiber distribution centers. By being twice or more, the sound absorbing property is high, and the cut portion is not crimped when cut in layers, and a sound absorbing material can be provided at a low cost. In other words, thin fibers have a large surface area, so they have high sound absorption, and thick fibers can be prevented from becoming a skeleton, forming a bulky and highly shape-retaining sheet, and the intersections of thick fibers and thin fibers can be bonded together. Strength, bulkiness, and high sound absorption can be exhibited by entanglement.

FIG. 1 is a photograph of a scanning electron microscope (SEM Hitachi scanning microscope S-2600N, magnification 3000 times) of the long-fiber nonwoven fabric obtained in one example of the present invention. FIG. 2A is a schematic cross-sectional view of a long-fiber nonwoven fabric obtained in one example of the present invention, and FIG. 2B is a schematic cross-sectional view of a long-fiber nonwoven fabric of another example of the present invention. FIG. 3A is a schematic explanatory view of a spinning machine used in one embodiment of the present invention, and FIGS. 3B-D are schematic explanatory views of a spinneret portion of the spinning machine. FIG. 4 is a graph showing normal incidence sound absorption coefficients of Example 1 and Comparative Example 1 of the present invention. FIG. 5 is a graph of normal incidence sound absorption coefficient of Example 2 and Comparative Example 2 of the present invention. FIG. 6 is a graph showing normal incidence sound absorption coefficients of Examples 3 to 5 and Comparative Example 3 of the present invention. FIG. 7 is a side photograph of the first embodiment of the present invention before punching. FIG. 8 is a side photograph after punching of Example 1 of the present invention. FIG. 9 is a side view of the comparative example 1 before the punching process. FIG. 10 is a side view of the comparative example 1 after the punching process.

  The present invention is a nonwoven fabric composed of long fibers. The long fiber nonwoven fabric can be produced by a melt blow method. The production cost of the long fiber nonwoven fabric by the melt blow method is low. An electrospinning method may be used in combination with the meltblowing method. The long fibers include relatively thick fibers and relatively thin fibers, and the fineness distribution center of the thick fibers is at least twice the fineness distribution center of the thin fibers, more preferably at least four times. . The fibers produced by the melt blowing method and / or the electrospinning method have non-uniform fineness but preferably have a fineness distribution center of 3.0 μm or less, more preferably 1.0 μm or less. The fineness distribution center is a central value obtained by measuring 50 measurements with a scanning electron microscope (SEM) at a magnification of 3000 times. By increasing the difference between the latitudinal distribution center of relatively thick fibers and the fineness distribution center of relatively thin fibers, it has high sound absorption and bulkiness. Crimping becomes a low-cost sound-absorbing material.

  Both thick and thin fibers are preferably undivided fibers. That is, it is a fiber that is produced by the melt-blowing method and / or the electrospinning method, and is a fiber that is not subjected to a splitting process or the like. There is a problem that the cost increases when the division processing is performed.

  Thick fibers and thin fibers have different melting points, and thick fibers preferably have a relatively high melting point. This is because the thick fibers in the nonwoven fabric become a skeleton to prevent sag and form a bulky and highly shape-retaining sheet.

  If the material of the fiber which comprises a nonwoven fabric is thermoplastic, there will be no restriction | limiting in particular, General resin will be used. For example, a thermoplastic resin such as polyester or a copolymer thereof or a mixture thereof, specifically, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTMT), isophthalic acid or phthalic acid The polymer may be a polymer such as polyamide or a copolymer thereof or a mixture thereof, or may be a polyolefin or a copolymer thereof or a mixture thereof. For example, a polypropylene obtained by random copolymerization of polyethylene (PE), polypropylene (PP), α-olefin, ethylene, or the like may be used. Further, it may be made of a resin in which a polyester resin, a polyamide resin, or an olefin resin is mixed. In particular, the material of relatively fine fibers is preferably polypropylene, in which fine fibers can be easily spun, and other components may be copolymerized as long as the properties of the polymer are not impaired. In order to enhance heat resistance and flame retardancy, various polymers such as polycarbonate, polyphenylene sulfide, polyamide, and thermoplastic polyimide may be used. As long as it has fiber-forming properties, it may be a mixture of two or more thermoplastic resins.

  The thick fiber is not particularly limited as long as it is thermoplastic, and a general resin is used. For example, it may be a polyolefin or a copolymer thereof or a mixture thereof. For example, polypropylene obtained by random copolymerization of polyethylene, polypropylene, α-olefin, ethylene, or the like may be used. Further, it may be made of a resin in which a polyester resin, a polyamide resin, or an olefin resin is mixed. In order to enhance heat resistance and flame retardancy, various polymers such as polycarbonate, polyphenylene sulfide, polyamide, and thermoplastic polyimide may be used. As long as it has fiber-forming properties, it may be a mixture of two or more thermoplastic resins. A thermoplastic resin such as polyester, a copolymer thereof, or a mixture thereof, in which thick and highly synthetic fibers are easily spun, is preferable. Specific examples include polyethylene terephthalate (PET), polytrimethylene terephthalate (PTMT), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN). Polymers such as isophthalic acid and phthalic acid, polyamides or copolymers thereof, or a mixture thereof are preferable, and other components may be copolymerized as long as the properties of the polymer are not impaired. Among these, PET and PBT are preferable.

It is preferable that a fuzz preventing layer is laminated on at least one surface of the nonwoven fabric. In this way, surface fibers can be prevented from fuzzing and caught, and the handleability is improved. The fuzz preventing layer may be any layer such as a woven fabric, a knitted fabric, a spunbonded nonwoven fabric, a fried layer, or a resin layer. The integration of the non-woven fabric and the fuzz-preventing layer includes melt holes in the thickness direction, thermal lamination, processing with an adhesive, hydroentanglement, and the like. When using a spunbonded nonwoven fabric, it is preferable to integrate with a melt hole in the thickness direction. The weight (unit weight) per unit area of the spunbonded nonwoven fabric is preferably 5 to 100 g / m ² , more preferably 10 to 50 g / m ² . The melt hole in the thickness direction can be formed by pin sonic processing using a high frequency roller.

The basis weight of the long-fiber nonwoven fabric of the present invention is preferably 10 to 10,000 g / m ² , more preferably 100 to 1000 g / m ² . The apparent density is preferably 0.005 to 0.30 g / cm ³ , more preferably 0.01 to 0.10 g / cm ³ .

  Next, the manufacturing method of a long-fiber nonwoven fabric is demonstrated. The long-fiber nonwoven fabric of the present invention is obtained by melt-extruding at least two types of polymers having different melting points from a spinneret, blowing off the extruded fibers with a pressure fluid, and forming the blown-off fibers into a sheet shape. . A method of blowing a fiber extruded by a pressure fluid to form a sheet is called a melt blow method. An electrode may be disposed in the vicinity of the sheet forming portion or the spinneret, and a voltage may be applied between the electrode and the spinneret. The method of applying voltage is called electrospinning. When a voltage is applied, the molten polymer extruded from the spinneret is charged and spun in the corresponding electrode direction. At this time, the long fiber of the present invention can be obtained by spinning at high speed with compressed air.

  In melt spinning, at least two kinds of polymers having different melting points and incompatible with each other may be melt-extruded from the same spinneret. As a result, a polymer having a high melting point becomes a thick fiber, and a polymer having a low melting point becomes a thin fiber. At least two types of polymers having different melting points may be melt extruded from different spinnerets. Similarly, a polymer having a high melting point becomes a thick fiber and a polymer having a low melting point becomes a thin fiber. However, since the amount of extrusion can be controlled, the ratio between the thin fiber and the thick fiber can be controlled. The ratio of fine fibers to thick fibers is preferably 90 to 20:10 to 80, more preferably 80 to 30:20 to 70, and even more preferably 70 to 50:30 to 50 in terms of mass ratio.

  Next, it demonstrates using drawing. FIG. 2A is a schematic cross-sectional view of the long fiber nonwoven fabric 15 obtained in one example of the present invention. This long-fiber nonwoven fabric 15 has a long-fiber layer 12 including thick and fine fibers, and a fusion hole 14 in the thickness direction by pin sonic processing using at least one surface of a spunbond nonwoven fabric layer 13 and a high-frequency roller. FIG. 2B is a schematic cross-sectional view of a long fiber nonwoven fabric 17 of another example. This long fiber nonwoven fabric 17 is obtained by subjecting at least one surface of a long fiber layer 12 containing thick fibers and fine fibers to a fried yarn, and 16 is a fried yarn layer. When the spunbond nonwoven fabric layer 13 or the fried layer 16 is provided, the surface fibers can be prevented from fuzzing and caught, and the handleability is improved.

  FIG. 3A is a schematic explanatory view of a spinning machine 11 used in an embodiment of the present invention, and FIGS. 3B-D are schematic explanatory views of a spinneret portion of the spinning machine. A melt extruder 2 is installed on the base 1, and polymer chips are supplied from the hopper 3 in the direction of arrow 4. The polymer melt-extruded by the extruder 2 is extruded from a die nose (spinneret) 5 and blown forward by compressed air discharged radially from a gas slot 6 formed in the vicinity of the dienose (spinneret) 5. Fibers are entangled in a Karman vortex by air resistance to form a fiber bundle, thereby forming a fiber assembly 8. An arrow 7 in FIG. 3A indicates the direction of pressure air supply from the roots blower. The fiber assembly 8 blown forward is turned into a sheet on the take-up roller 9 and taken up. Reference numeral 10 denotes a wound long fiber nonwoven fabric. A metal net may be disposed in place of the take-up roller 9. A voltage of about 10 to 100 kV may be applied to the dynose (spinneret) 5 and the take-up roller 9 or the metal net. The pressure supply direction is set not only to the front of the die nozzle but also to an optimum angle for spinning such as straight and 45 degrees obliquely forward depending on the properties of the polymer. As an example, as shown in FIGS. 3B-D, one or a plurality of gas slots 6a, 6b, 6c, 6d may be arranged.

Hereinafter, more specific description will be made using examples. In addition, this invention is not limited to the following Example.
<Measurement method>
1. Thickness Ten points were measured with a large snap gauge K-7 manufactured by Ozaki Seisakusho, a probe diameter of 100 mm, and a weight of 2.5 g / cm ² , and the display range was obtained.
2. Sound absorption test Using a Brüel & Kjær type 4206T, the normal incident sound absorption coefficient specified in JIS A1405-2 was measured. The normal incident sound absorption coefficient defined in JIS A1405-2 is defined as the ratio of the acoustic power that enters (does not return to) the specimen surface with respect to the incident acoustic power for a plane wave that enters perpendicularly.

(Example 1, Comparative Example 1)
Blended polypropylene (Nippon Polypro Corporation, trade name “Novatech”, PP) and polybutylene terephthalate (Mitsubishi Engineering Plastics, trade name “Novaduran”, PBT). = 70: 30), and supplied from the hopper 4 of the melt spinning apparatus shown in FIG. 3, melt extruded from the melt extruder 2, and spun. The spinning temperature is 320 ° C., the extrusion rate of the polymer from the die nose (spinneret) 5 is 5 g / min, 0.5 Mpa of compressed air is sprayed from the pores having a diameter of 1 mm to the die nose, and the long fiber nonwoven fabric 10 is wound by the winding roll 9. Rolled up. The fine fiber distribution center of the thick nonwoven fabric (PBT) obtained was 4.3 μm, and the fine fiber distribution center of the thin fiber (PP) was 0.9 μm.

The obtained long fiber nonwoven fabric is flattened, and a spunbond nonwoven fabric having a basis weight of 15 g / m ² and a thickness of 0.11 mm is laminated on both the front and back surfaces of this nonwoven fabric, and melt holes in the thickness direction are obtained by pin sonic processing using a high frequency roller. The long fiber nonwoven fabric spunbond nonwoven fabric was integrated. The pitch interval of the melt holes in the thickness direction was 25 mm. The obtained long fiber nonwoven fabric had a basis weight of 190 g / m ² and a thickness of 10 mm.

  FIG. 1 is a photograph of a scanning electron microscope (SEM Hitachi scanning microscope S-2600N, magnification 3000 times) of the long-fiber nonwoven fabric obtained in Example 1. The fibers extending in an L shape at the upper right and lower portions are thick fibers (PBT), and the surrounding fibers are thin fibers (PP). FIG. 2A is a schematic cross-sectional view of the obtained long fiber nonwoven fabric 15.

Using the long-fiber nonwoven fabric obtained in Example 1 and one comparative example product (commercially available from 3M, trade name “Synsalate”, TAI-2047, basis weight is 200 g / m ² , thickness 10 mm), a sound absorption test was performed. did. FIG. 4 shows a graph of normal incidence sound absorption coefficient of the product of Example 1 and the product of Comparative Example 1. The product of Example 1 had a higher normal incident sound absorption coefficient than the product of Comparative Example 1, and the superiority of the product of Example 1 was recognized.

(Example 2, comparative example 2)
The experiment was performed in the same manner as in Example 1 except that the basis weight of the long fiber nonwoven fabric was 150 g / m ² and the thickness was 7 mm. A sound absorption test was carried out using two products of Example 2 and two products of Comparative Example (commercially available from 3M, trade name “Synsalate”, TAI-1547, basis weight 150 g / m ² , thickness 7 mm). FIG. 5 shows a graph of normal incidence sound absorption coefficient of the product of Example 2 and the product of Comparative Example 2. The product of Example 2 had a slightly higher normal incidence sound absorption coefficient than the product of Comparative Example 2.

(Examples 3 to 5, Comparative Example 3)
Blended chips of polypropylene (made by Nippon Polypro Co., Ltd., trade name “Novatec”, PP) and polyethylene terephthalate (trade name “Biopellet EMC307”, PET made by Toyobo Co., Ltd.) (PP: PET = 70 by weight) 30), and supplied from the hopper 4 of the melt spinning apparatus shown in FIG. 3, melt extruded from the melt extruder 2, and spun. The spinning temperature is 320 ° C., the extrusion amount of the polymer from the die nose (spinneret) 5 is 5 g / min, 0.5 Mpa of compressed air is sprayed from the pores having a diameter of 1 mm to the die nose, and the long-fiber nonwoven fabric 10 is wound by the winding roller 9. Was taken up as Example 3. The fine fiber distribution center of the thick fibers of the obtained long fiber nonwoven fabric was 4.3 μm, and the fine fiber distribution center of the thin fibers was 0.9 μm. The obtained long fiber nonwoven fabric had a basis weight of 320 g / m ² and a thickness of 11 to 12 mm.

  Except as shown in Table 1, the long fiber nonwoven fabrics of Examples 4 to 5 were prepared in the same manner as in Example 3. However, PET (low viscosity) shown in Table 1 has an intrinsic viscosity of 0.58 when a dilute solution obtained by dissolving a polymer chip in orthochlorophenol at 100 ° C. for 60 minutes at 35 ° C. using an Ubbelohde viscometer is used. PET (high viscosity) indicates a polymer having an intrinsic viscosity of 0.70.

A long fiber nonwoven fabric was prepared in the same manner as in Example 3 using only the polypropylene chip of Example 3, and this was designated as Comparative Example 3. Pinsonic using a high-frequency roller by flattening the long-fiber nonwoven fabrics of Comparative Example 3 and Examples 3 to 5 and laminating a polypropylene spunbond nonwoven fabric having a basis weight of 20 g / m ² and a thickness of 0.18 mm on both front and back surfaces of the nonwoven fabric. The long fiber nonwoven fabric spunbonded nonwoven fabric was integrated with the melt holes in the thickness direction by processing. The pitch interval of the melt holes in the thickness direction was 25 mm. The bulkiness and normal incidence sound absorption coefficient of Comparative Example 3 and Examples 3 to 5 were compared. Table 1 shows the sample preparation conditions and bulkiness results, and FIG. 6 shows the normal incidence sound absorption coefficient.

The following can be seen from Table 1 and FIG.
(1) Compared with Comparative Example 3 in which only fine fibers were used, in Examples 3 to 5 in which thick and fine fibers were mixed, a bulky and highly shape-retaining sheet was obtained. This is because the long fiber nonwoven fabric is thick and bulky because of the thick fibers that form the skeleton.
(2) In Examples 3 to 5, the thickness of the high frequency roller during pin sonic processing is small, and the bulkiness is high.
(3) On the other hand, in the ratio of thin fibers to thick fibers, the thicker the thick fibers, the thicker, the less sag of the thickness due to the high frequency roller during pin sonic processing, and high bulkiness.
(4) The fine fiber distribution center of the thin fibers of Comparative Example 3 and Example 3 is 0.9 μm, and there is almost no difference in the normal incident sound absorption coefficient. However, Comparative Example 3 was formed only with thin fibers, and was bulky and inferior to shape retention Example 3. On the other hand, in Example 3, thick fibers were mixed, the thickness of the high-frequency roller during pin sonic processing was small, and it was an excellent sound-absorbing material that was both bulky and highly shaped.
(5) The fineness distribution center of the thin fiber of Example 4 is 2.1 μm, the fineness distribution center of the thin fiber of Example 5 is 2.3 μm, and the fineness distribution center of the thin fiber of Comparative Example 3 is thinner than 0.9 μm. The fiber fineness distribution center is thick and the sound absorption coefficient is slightly low. However, thick fibers were mixed in Examples 4 to 5, and the thickness of the high frequency roller during pin sonic processing was small. In comparison with Comparative Example 3, Examples 4 to 5 were excellent sound absorbing materials that had a high normal incident sound absorption coefficient and a bulky and high shape retention.

(Cut surface crimping by punching)
Three long fiber nonwoven fabrics of Example 1 and Comparative Example 1 were stacked and punched with a cutting blade (Thomson blade). 7 is a side view before punching of Example 1 of the present invention, FIG. 8 is a side view of after punching of Example 1 of the present invention, FIG. 9 is a side photograph before punching of Comparative Example 1, FIG. These are side photographs after the punching process of Comparative Example 1. The product of Example 1 was divided into three pieces after punching (FIG. 8), and three pieces could be processed simultaneously. On the other hand, the cut portion of the comparative example 1 product was pressed and the three pieces were integrated (FIG. 10), and it was necessary to punch one by one. This is because the product of Example 1 of the present invention is excellent in punching workability, and there is an advantage that the manufacturing cost when manufacturing the punched product can be reduced.

DESCRIPTION OF SYMBOLS 1 Base 2 Melt extruder 3 Hopper 4 Polymer chip supply direction 5 Spinneret 6, 6a-6d Gas slot 7 Pressure air supply direction 8 Fiber assembly 9 Winding roll 10 Winded long fiber nonwoven fabric 11 Spinning machine 12 Long fiber layer 13 Spunbond non-woven fabric layer 14 Melting hole 15, 17 Long fiber non-woven fabric 16

Claims (4)

A non-woven sound absorbing material composed of long fibers,
The long fibers are mixed Nde contains fine fibers having a relatively fineness and thick relatively fineness fibers,
Fineness distribution center of the thick fibers, Ri Oh more than 2 times the fineness of the distribution center of the fine fibers,
The ratio of the thin fiber to the thick fiber is a mass ratio, and the fine fiber: thick fiber = 80-30: 20-70,
A nonwoven fabric sound-absorbing material, characterized in that a spunbond nonwoven fabric is laminated on at least one main surface of the nonwoven fabric, and is integrated with melt holes in the thickness direction by pin sonic processing .   The sound absorbing material made of nonwoven fabric according to claim 1, wherein the thin fibers are polypropylene and the thick fibers are polyester.   The nonwoven fabric sound-absorbing material according to claim 1, wherein a fuzz preventing layer is laminated on at least one surface of the nonwoven fabric.   The nonwoven fabric sound-absorbing material according to any one of claims 1 to 3, wherein at least one main surface of the nonwoven fabric is burnt.