JP5284855B2 - Damping materials and damping composites - Google Patents

Description

  The present invention relates to a vibration damping material, and further relates to a material applied to an acoustic member, a structural member or the like that needs to dampen vibrations, and more particularly to a vibration damping material suitably applied to a speaker damper. is there.

  At the same time, a damping material that suppresses vibrations is widely required for devices and members that easily transmit vibrations or are damaged by vibrations. It is applied in a wide range of fields such as measuring equipment and audio equipment. The damping material converts vibration energy into thermal energy and reduces the vibration of the solid surface. As a result, the vibration radiated from the solid surface is attenuated, particularly in the vibration attenuation near the resonance point of the vibration surface. It is valid.

It has been reported that a melt blown nonwoven fabric having a cross-sectional diameter of 6 μm or less is used as a material having excellent vibration damping characteristics (Patent Document 1).
However, in the polypropylene fiber having an average cross-sectional diameter of 3 μm described in the example of the above cited reference 1, there is a limit to application in hot-pressure processing such as resin molding processing when processing the damping member. . Further, since the fiber has a cross-sectional diameter of the order of micrometer, it cannot be said that the vibration damping property is sufficient, and further, sufficient performance cannot be obtained even when used for an acoustic member.

JP 2001-279570 A

  An object of the present invention is to provide a vibration damping material and a vibration damping composite material having an improved loss factor and improved vibration damping properties.

As a result of intensive studies by the present inventors, it has been found that the above problems can be solved by adopting the configuration described below.
That is, the present invention comprises a wholly aromatic polyamide nanofiber having a cross-sectional diameter of 10 to 500 nm perpendicular to the fiber axis direction, and the wholly aromatic polyamide nanofiber includes a repeating structural unit represented by the following formula (1). In the aromatic polyamide skeleton, an aromatic diamine component or an aromatic dicarboxylic acid halide component different from the main structural unit of the repeating structure is 1 to 10 mol% with respect to the total amount of the repeating structural unit of the aromatic polyamide as the third component. The vibration damping material is made of wholly aromatic polyamide copolymerized .
-(NH-Ar1-NH-CO-Ar1-CO) -... Formula (1)
Here, Ar1 is a divalent aromatic group having a bonding group other than in the meta-coordination or parallel axis direction.

Further, the present invention provides a fiber shaft on a substrate made of at least one of a woven fabric, a knitted fabric, a dry nonwoven fabric, a wet nonwoven fabric, or a film made of fibers having a cross-sectional diameter of 0.5 to 30 μm perpendicular to the fiber axis direction. In the aromatic polyamide skeleton, which is formed by laminating wholly aromatic polyamide nanofibers having a cross-sectional diameter of 10 to 500 nm perpendicular to the direction, and the aromatic polyamide nanofiber includes a repeating structural unit represented by the following formula (1) In addition, an aromatic diamine component or an aromatic dicarboxylic acid halide component different from the main structural unit of the repeating structure is copolymerized so as to be 1 to 10 mol% based on the total amount of the repeating structural unit of the aromatic polyamide as the third component. A vibration-damping composite material made of wholly aromatic polyamide .
-(NH-Ar1-NH-CO-Ar1-CO) -... Formula (1)
Here, Ar1 is a divalent aromatic group having a bonding group other than in the meta-coordination or parallel axis direction.

  The vibration damping material of the present invention is composed of aromatic polyamide nanofibers and exhibits excellent vibration damping properties. Further, the vibration damping material is excellent in terms of strength and heat resistance, and a vibration damping material excellent in various workability is provided.

The vibration damping material of the present invention is characterized by comprising a wholly aromatic polyamide nanofiber having a cross-sectional diameter of 10 to 500 nm perpendicular to the fiber axis direction. By using such a damping material, the wide specific surface area of the nanofibers can efficiently transmit vibration energy to the entire nanofiber or to the substrate when it is laminated on the substrate. And exhibits high vibration control. Further, since the vibration damping material is lightweight, it is possible to increase the efficiency.

  The cross-sectional diameter of the wholly aromatic polyamide nanofiber needs to be 10 to 500 nm as described above, and preferably 30 to 300 nm. Here, the cross-sectional diameter means an average value of cross-sectional diameters of 100 nanofibers arbitrarily sampled. In the present invention, the cross-sectional diameter is concentrated at 10 to 500 nm, and it is preferable that the cross-sectional diameter is 85% or more within the range of the cross-sectional diameter. If the cross-sectional diameter is less than 10 nm, the fiber is likely to be broken, so that the ability to transmit vibration is inferior, and the fiber is liable to break during processing or use. Is not preferable because the contact point between the nanofibers and the contact point between the nanofibers and the substrate are reduced. Therefore, when nanofibers outside the above range are present in excess of 15%, it tends to be difficult to obtain the desired vibration damping properties.

  The vibration damping material may be a vibration damping material obtained by laminating the wholly aromatic polyamide nanofibers on a fiber structure composed of at least one of woven fabric, knitted fabric, dry nonwoven fabric, and wet nonwoven fabric. . The fiber preferably has a cross-sectional diameter of 0.5 to 10 μm.

In the present invention, an aromatic diamine component in which the wholly aromatic polyamide nanofiber is different from the main structural unit of the repeating structure in the aromatic polyamide skeleton containing the repeating structural unit represented by the following formula (1) , or the aromatic dicarboxylic acid halide component, consisting of 1 to 10 mol% and so as aromatic polyamides obtained by copolymerizing with respect to the total amount of the repeating structural units of aromatic polyamide as a third component.
-(NH-Ar1-NH-CO-Ar1-CO) -... Formula (1)
Here, Ar1 is a divalent aromatic group having a bonding group other than in the meta-coordination or parallel axis direction.

Moreover, in this invention, it is preferable that the aromatic diamine used as said 3rd component is Formula (2) or (3), and an aromatic dicarboxylic acid halide is Formula (4) or (5).
H ₂ N—Ar 2 —NH ₂ Formula (2)
_{H 2 N-Ar 2 -Y-} Ar 2 -NH 2 ··· formula (3)
XOC-Ar 3 -COX ··· formula (4)
XOC-Ar 3 -Y-Ar 3 -COX ··· formula (5)
Here, Ar2 is a divalent aromatic group different from Ar1, Ar3 is a divalent aromatic group different from Ar1, Y is at least one atom selected from the group consisting of an oxygen atom, a sulfur atom, and an alkylene group Or it is a functional group and X represents a halogen atom.

  By copolymerizing the third component as described above, the stability of the spinning solution is improved, it is difficult to break the yarn, and the formed nanofibers have little expression of nodular polymer mass called beads, It becomes easy to obtain nanofibers of long fibers having a large cross-sectional diameter. For this reason, vibration energy can be efficiently transmitted, and the vibration damping tends to be improved, which is more preferable. In addition, there is a method of adding an alkali metal salt or the like to stabilize the spinning solution. However, it may not be preferable that the salt remains in the nanofiber. It is more effective to use nanofibers that are polymerized and have no yarn breakage.

  If the content of the third component is less than 1 mol%, gelation occurs in the spinning solution, which is not preferable. If the content exceeds 10 mol%, the viscosity of the spinning solution increases, and nanofibers having a target cross-sectional diameter are not obtained. It is difficult to obtain and is not preferable.

  The aggregate form of the nanofibers is preferably a nonwoven fabric. Thus, since the nanofiber does not produce directionality by adopting a nonwoven fabric form in which the fiber axis direction is not aligned, such as a woven fabric, it is suitable as a vibration damping material.

Basis weight of the damping material, preferably ^{0.5~10.0g / m 2, 0.8~3.0g / m} 2 is more preferable. If the weight per unit area is less than 0.5 g / m ² , sufficient vibration damping performance cannot be obtained, and handling becomes difficult. On the other hand, even if it exceeds 10.0 g / m ² , the effect of improving the vibration damping performance is large. Not preferable.

In the present invention, the total fragrance is formed on a substrate made of at least one of a woven fabric, a knitted fabric, a dry nonwoven fabric, a wet nonwoven fabric, or a film made of fibers having a cross-sectional diameter of 0.5 to 30 μm perpendicular to the fiber axis direction. It is good also as a damping composite material formed by laminating group polyamide nanofibers. The base material can be selected according to the damping application to be used. For example, a woven fabric such as wholly aromatic polyamide fiber, acrylic fiber, and cotton fiber can be preferably used for the speaker damper. In addition to the above, polymers constituting fibers used for fabrics and the like, and polymers constituting films include polyethylene terephthalate, polyethylene naphthalate, polyesters such as polylactic acid, polyamides such as nylon, polypropylene, polyethylene, etc. Polyolefin type can also be used.

Basis weight of the substrate is preferably from ^{50~400g / m 2, 100~300g / m} 2 is more preferable. If the weight per unit area is less than 50 g / m ² , the strength decreases, whereas if it exceeds 200 g / m ² , vibration damping tends to decrease.

  In the present invention, the weight of the nanofiber is preferably 0.1 to 5% by weight, more preferably 0.3 to 5% by weight, based on the weight of the base material in the above-described vibration-damping composite material. By setting the ratio, a good acoustic effect (loss factor) can be obtained using this as an acoustic member, particularly a speaker damper.

  In the vibration damping composite material, a part of the wholly aromatic polyamide nanofiber may be melted or softened to form a film and bonded to the substrate. The damping composite material having such a form is obtained by laminating an aromatic polyamide nanofiber on a base material, and then subjecting this to a heating and pressurizing treatment. And the base material are more closely adhered to each other.

  The damping material and damping composite material of the present invention described above can be manufactured, for example, by the following method. One method is to spray a wholly aromatic polyamide solution on a paper, film, fabric, etc. in the case of a damping material or on a substrate in the case of a damping composite by applying a high voltage. Thus, a method for forming nanofibers can be preferably exemplified. Further, the cross-sectional diameter of the obtained nanofiber depends on the applied voltage, the solution concentration, the spray scattering distance, and the like, and can be set to an arbitrary cross-sectional diameter by adjusting these conditions. As the solvent, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide and the like can be used.

  Specifically, a polymer solution in which a wholly aromatic polyamide polymer and a solvent are dissolved at a weight ratio of 1:99 to 16:84 is prepared, and the spinning distance is 5.0 to 50 cm under a voltage of 5 to 70 kV. Then, when converted into a voltage per unit distance, a wholly aromatic polyamide nanofiber having the aforementioned cross-sectional diameter can be produced by performing electrospinning at 0.5 to 7.0 kv / cm.

  Examples of the spinning solution supply include a method of extruding from a nozzle and a base, and a method of supplying the spinning solution by attaching it to a disk or drum immersed in the spinning solution so that it becomes a required amount and continuously rotating it.

  Similarly, nylon, polyvinyl alcohol, etc. are known as polymers capable of forming nanofibers by electrospinning. However, these conventional nanofibers are insufficient in practical use or processed at high temperatures. In this case, there is a problem that it is easy to melt, and it is not suitable for use as a damping material. However, these problems can be solved by using wholly aromatic nanofibers.

  In addition, in the electrospinning, by using the wholly aromatic polyamide copolymerized with the specific third component described above, a wholly aromatic polyamide nanofiber that is uniform and has no yarn breakage is obtained, and has excellent damping characteristics. Damping material can be used.

  Furthermore, a vibration-damping composite material in which a part of the above-mentioned aromatic polyamide nanofiber is melted or softened to form a film and is joined to the substrate includes, for example, an aromatic polyamide nanofiber on the substrate. After being laminated, it can be produced by subjecting it to heat and pressure treatment at a temperature of 30 to 350 ° C. and a linear pressure of 50 to 300 kgf / cm using a calendaring device, an embossing device or the like.

Damping material and vibration-damping composite material of the present invention is suitable for the acoustic member, in particular vibration-damping composite material of the present invention is suitable for the speaker damper. As a specific effect, the vibration damping composite material in which aromatic polyamide nanofibers are laminated can improve the loss coefficient measured by JIS G0602-1993 by 10% or more with respect to the base material alone.

When using a vibration-damping composite material speaker damper, the substrate, or the substrate and nanofibers resin may be impregnated. As the resin, phenol resin, melamine resin, epoxy resin, urethane resin, or the like can be used.

  The vibration damping material and the vibration damping composite material of the present invention may be used by laminating two or more layers, preferably 2 to 10 layers, depending on the application. At that time, the resin is impregnated and subjected to heat and pressure treatment as described above. These are preferably formed into an integrated molded body.

  Hereinafter, the present invention will be described specifically by way of examples. In the examples, the following methods were used.

(1) Cross-sectional diameter Arbitrarily 100 nanofibers were sampled and measured with a scanning electron microscope JSM6330F (manufactured by JEOL), and the average cross-sectional diameter was determined. The measurement was performed at a magnification of 30,000 times.

(2) Number of beads The surface of the nanofiber was sampled arbitrarily at 10 locations, measured with a scanning electron microscope JSM6330F (manufactured by JEOL), the number of beads exceeding 1 μm was counted in the long axis direction of the beads, and the average value was calculated. . The measurement was performed at a magnification of 1,000 times and a field of view of about 90 × 120 μm.

(3) Loss factor and rate of increase in loss factor The loss factor and the rate of increase in the loss factor were implemented in accordance with JIS G0602-1993 one-end fixed impact excitation method. The test piece was cut into 10 mm × 45 mm, and 5 measurement samples were arbitrarily selected. One end of the sample was fixed to the sample stage, and the amplitude generated by the impact given to the open one end was taken into a CCD laser mutation meter and FFT analyzer and analyzed. The loss coefficient η was calculated by the following formula.
Λ = log _e (X ₀ / X ₁ ) = 1 / nlog _e (X ₀ / X _n )
Λ: logarithmic decay rate, X ₀ : amplitude distortion, X _n : nth amplitude distortion η = Λ / π
The loss factor was measured only for the damping composite material sample and the base material, and the rate of increase relative to the loss coefficient of the base material only (Comparative Example 1) was calculated from the following equation.
Loss coefficient increase rate [%] = (loss coefficient of sample / loss coefficient of base material only) × 100

[ Reference example ]
Basis weight consisting of Teijin Techno Products Co. Conex spun yarn 20 fastest (single fiber cross-sectional diameter 15 [mu] m) is phenol resin impregnated into the fabric of 163 g / ^{m 2,} a basis weight creates a substrate of 175 g / ^{m 2.}
On the other hand, an aromatic polyamide polymer was produced as follows by an interfacial polymerization method according to the method described in Japanese Patent Publication No. 47-10863.
25.25 g (100 mol%) of isophthalic acid dichloride was dissolved in 125 ml of tetrahydrofuran having a water content of 2 mg / 100 ml and cooled to −25 ° C. While stirring this, 13.52 g (100 mol%) of metaphenylenediamine was added over about 15 minutes as a trickle of a solution obtained by dissolving 125 ml of the above tetrahydrofuran to prepare a white emulsion (A). Separately, 13.25 g of anhydrous sodium carbonate was dissolved in 250 ml of water at room temperature, and this was cooled to 5 ° C. with stirring to precipitate sodium carbonate hydrate crystals to prepare a dispersion (B). The emulsion (A) and dispersion (B) were mixed vigorously. After further mixing for 2 minutes, 200 ml of water was added for dilution, and the resulting polymer was precipitated as a white powder. Filtration, washing with water and drying were carried out from the polymerization completed system to obtain the desired polymer. The intrinsic viscosity IV measured for the obtained polymer was 1.68.

Electrospinning produced nanofibers according to the method described in JP-A-2006-336173. The obtained polymer was dissolved in N, N-dimethylacetamide so as to be 10% by weight, electrospun was performed by applying an electric field so as to be 1 kV / cm, and nanofibers were laminated on the substrate. To obtain a laminate. Five obtained laminates were stacked and subjected to heat and pressure treatment at 250 ° C. and 150 kgf / cm ² with a press machine to obtain a vibration-damping composite material. The basis weight of the nanofiber was 1.0 g / m ² (0.57% by weight based on the weight of the substrate). The results are shown in Table 1.
Further, only one piece of the above laminate is not used and heat-pressing treatment is performed under the same conditions to form a damping composite material, and a speaker damper having a diameter of 80 mm is cut out from the obtained damping composite material. The sound quality was clearer than that of Comparative Example 1.

[ Example 1 ]
A vibration-damping composite material in the same manner as described in Reference Example , except that 25.13 g (99 mol%) of isophthalic acid dichloride and 0.25 g (1 mol%) of terephthalic acid dichloride were used instead of 100 mol% of isophthalic acid dichloride. Got. The results are shown in Table 1. In addition, a speaker was created and auditioned as in the reference example , but the sound quality was clearer than in Comparative Example 1.

[ Example 2 ]
A vibration-damping composite material was obtained in the same manner as described in Example 1 except that the wholly aromatic polyamide nanofibers were laminated on both surfaces of the substrate and subjected to heat and pressure treatment. The basis weight of the nanofibers per one laminate was 2.0 g / m ² (1.14% by weight based on the weight of the base material). The results are shown in Table 1. In addition, a speaker was created and auditioned as in the reference example , but the sound quality was clearer than in Comparative Example 1.

[ Example 3 ]
A damping composite material was obtained in the same manner as in Example 1 except that a wholly aromatic polyamide powder and a polymer solution in which the solvent N, N-dimethylacetamide was dissolved at a weight ratio of 7:93 were used. The results are shown in Table 1. In addition, a speaker was created and auditioned as in the reference example , but the sound quality was clearer than in Comparative Example 1.

[ Example 4 ]
A damping composite material was obtained in the same manner as in Example 1 except that a wholly aromatic polyamide powder and a polymer solution in which the solvent N, N-dimethylacetamide was dissolved at a weight ratio of 12:88 were used. The results are shown in Table 1. In addition, a speaker was created and auditioned as in the reference example , but the sound quality was clearer than in Comparative Example 1.

[Comparative Example 1]
A damping material was obtained in the same manner as in the Reference Example except that the wholly aromatic polyamide nanofibers were not laminated and only the base material was used. The results are shown in Table 1. Moreover, and creating audition speaker in the same manner as in Reference Example were compared Reference Examples and quality of Examples 1 to 4 and as a reference.

[Comparative Example 2]
A polymer solution was prepared by dissolving polyvinyl alcohol manufactured by Kuraray Co., Ltd. in water at a weight ratio of 17:85 and used instead of the wholly aromatic polyamide polymer solution. After the heat and pressure treatment, the nanofibers could not be confirmed when observed with an operation electron microscope, and thus the evaluation was not performed.

The vibration damping material and the vibration damping composite material of the present invention have a significantly improved loss factor and improved vibration damping properties, and can be applied in a wide range of fields such as precision measurement equipment and audio equipment. Moreover, vibration-damping composite material of the present invention, the acoustic member may be suitably used especially speaker damper.

Claims (5)

In the aromatic polyamide skeleton comprising a wholly aromatic polyamide nanofiber having a cross-sectional diameter of 10 to 500 nm perpendicular to the fiber axis direction, the wholly aromatic polyamide nanofiber comprising a repeating structural unit represented by the following formula (1) In addition, an aromatic diamine component or an aromatic dicarboxylic acid halide component different from the main structural unit of the repeating structure is copolymerized so as to be 1 to 10 mol% based on the total amount of the repeating structural unit of the aromatic polyamide as the third component. Damping material made of wholly aromatic polyamide .
-(NH-Ar1-NH-CO-Ar1-CO) -... Formula (1)
Here, Ar1 is a divalent aromatic group having a bonding group other than in the meta-coordination or parallel axis direction. The damping material according to claim 1, wherein the aromatic diamine as the third component is represented by formula (2) or (3), and the aromatic dicarboxylic acid halide is represented by formula (4) or (5).
H ₂ N—Ar 2 —NH ₂ Formula (2)
_{H 2 N-Ar 2 -Y-} Ar 2 -NH 2 ··· formula (3)
XOC-Ar 3 -COX ··· formula (4)
XOC-Ar 3 -Y-Ar 3 -COX ··· formula (5)
Here, Ar2 is a divalent aromatic group different from Ar1, Ar3 is a divalent aromatic group different from Ar1, Y is at least one atom selected from the group consisting of an oxygen atom, a sulfur atom, and an alkylene group Or it is a functional group and X represents a halogen atom. Fabric cross-sectional diameter perpendicular to the fiber axis direction is made of fibers of 0.5 to 30 m, knitted, dry nonwoven fabric, wet-laid nonwoven fabric or onto a substrate made of at least one of the film, the cross-sectional diameter perpendicular to the fiber axis Is formed by laminating wholly aromatic polyamide nanofibers of 10 to 500 nm, and the wholly aromatic polyamide nanofibers have a repeating structure in an aromatic polyamide skeleton containing repeating structural units represented by the following formula (1). A wholly aromatic copolymerized aromatic diamine component or aromatic dicarboxylic acid halide component different from the main structural unit so as to be 1 to 10 mol% based on the total amount of repeating structural units of the aromatic polyamide as the third component Damping composite material made of polyamide .
-(NH-Ar1-NH-CO-Ar1-CO) -... Formula (1)
Here, Ar1 is a divalent aromatic group having a bonding group other than in the meta-coordination or parallel axis direction. The vibration-damping composite material according to claim 3 , wherein the weight of the wholly aromatic polyamide nanofiber is 0.1 to 5% by weight with respect to the weight of the substrate. A speaker damper comprising the vibration-damping composite material according to claim 3 .