JP2012243993A - Noise absorption cloth - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noise absorption cloth having excellent noise absorption capacity on which electromagnetic waves are hardly reflected.SOLUTION: In the noise absorption cloth 1 where a conductive polymer 3 is adhering to the fibers of a cloth 2, the common logarithm of the surface resistivity on at least one surface of the noise absorption cloth 1 is set in the range of 0-4.

Description

  The present invention relates to a noise-absorbing fabric having a specific surface resistivity with a conductive polymer attached to the fabric fibers.

  With the full-scale spread of electronic devices such as personal computers and large-screen TVs, wireless communication devices such as mobile phones and wireless LANs, the amount of information handled has increased significantly. For this reason, these electronic devices and wireless communication devices have higher capacity, higher integration, and higher speed communication, and there is an increasing demand for processing an increasing amount of information faster and transmitting more efficiently. . In order to satisfy these requirements, the clock frequency of the LSI and the transmission frequency used in the electronic device are shifted to a higher frequency side, and the use frequency of the communication device is also higher.

Higher usage frequency makes it easier for other devices to malfunction due to noise generated from electronic devices, and interference with radio waves used by communication devices tends to cause problems with electronic devices and communications. It has been reported.
For this reason, there is an increasing need for a noise absorber that absorbs noise generated from electronic equipment as a so-called EMC countermeasure for the purpose of preventing electromagnetic interference against electronic components, transmission lines, etc., and communication systems. Yes.

  In addition, the shift to a ubiquitous society has led to an increase in mobile personal computers, and mobile phones have become smaller and higher in performance. Therefore, devices and materials that can be reduced in size and weight are desired.

  Patent Documents 1 and 2 disclose a noise absorbing sheet in which a soft magnetic material is dispersed in a resin and is put into practical use. The principle of the performance of the noise absorbing sheet is that the soft magnetic material dispersed in the resin captures the electromagnetic wave and magnetically polarizes, and the electromagnetic loss is converted into heat energy by the magnetic loss at that time. is there. Since the soft magnetic material is a powder, it is necessary to knead and disperse in the resin, but since the soft magnetic material is a powder with high hardness, it is possible to uniformly disperse it in the resin at a higher concentration. difficult. Moreover, since the manufactured sheet | seat is difficult to wind up on a roll, it was not suitable for continuous production, such as an electronic device.

  Furthermore, since the noise absorbing sheet is a sheet in which a soft magnetic powder having a high specific gravity is dispersed, the thickness thereof is thick and it is difficult to incorporate it in a narrow place. The matrix resin of the noise absorbing sheet is selected from a rubbery material in consideration of ease of use, but it is difficult to incorporate it into a place with a high curvature and to use it by bending.

  Furthermore, it is known that a powder having a complicated composition and structure of a soft magnetic material is used for a noise absorbing sheet in order to cope with a higher frequency. For example, although attempts have been made to control magnetism by using rare metals and / or microelements as raw materials for soft magnetic materials and making them more complex compounds, there may be a cost problem. Although attempts have been made to increase the polarization of soft magnetic materials using soft magnetic materials such as needles and scales, it is very difficult to increase the concentration of soft magnetic materials to make uniform sheets, and the cost And there was a problem in handling.

  Further, the noise absorbing sheet in which the soft magnetic material is dispersed in the resin absorbs noise of a specific frequency, but it is difficult to absorb broadband noise. For this reason, studies have been made to mix and produce particles that are effective for various frequencies. However, there is a limit to the amount of particles that can be added to form a sheet, and noise absorption over a wide band. It was difficult to demonstrate the ability.

  Patent Documents 3 and 4 disclose noise absorbing sheets in which a soft magnetic material or metal is processed on the surface of a resin sheet. However, since the above-mentioned noise absorbing sheet has a soft magnetic material or metal deposited on a resin sheet or film-like material, the surface is smooth and it is difficult to achieve higher performance. Therefore, in order to improve the performance, it has been attempted to divide the function into multiple layers and stack them, but it is difficult to improve the performance, and it is thick and difficult to use.

Patent Documents 5 and 6 disclose a sheet-like composite magnetic body and a noise absorber, respectively. However, since the articles described in Patent Documents 5 and 6 both have a smooth surface, the conductivity of the metal itself increases the reflection of electromagnetic waves and inhibits the absorption of electromagnetic waves. .
As shown in Patent Documents 3 to 6, when a magnetic material or metal material layer is formed on a smooth surface such as a film or sheet, the magnetic material or metal material layer becomes smooth, and the magnetic material or metal material originally has Conductivity becomes obvious, and electromagnetic waves are reflected by its large conductivity. These amplify noise by resonance of electromagnetic waves rather than absorbing noise.

  Patent Document 7 discloses a noise absorbing sheet in which a layer containing conductive fibers and a layer containing a magnetic material are laminated. However, in the noise absorbing sheet of Patent Document 7, the noise absorbing ability is mainly caused by the magnetic material, and it has not been clear whether the conductive fiber has the noise absorbing ability. Furthermore, in a region where the proportion of conductive fibers is large and the conductivity is excessively large, there is a problem that the reflection of electromagnetic waves becomes strong and the absorptivity is hindered.

  Patent Document 8 describes a noise suppression sheet in which conductive fibers are dispersed in a resin instead of the soft magnetic material disclosed in Patent Document 1 or 2. However, the conductive fiber used in Patent Document 8 is a general material and does not have noise absorbing ability. That is, since the conductive fibers are dispersed in the resin as if to replace the needle-like soft magnetic material, the noise absorbing ability is not as good as that of the resin dispersion sheet product of the soft magnetic material as disclosed in Patent Document 1. It was. Further, the principle of operation has not been elucidated, and the sheet does not have practicality as a noise absorbing sheet, such as one that does not exhibit noise absorbing ability at all, or one that has excessively strong reflection of electromagnetic waves.

  Further, Patent Document 9 proposes a radio wave absorber in which a fiber sheet is coated with polypyrrole or polythiophene, but electromagnetic wave return loss (S11) by stacking a plurality of sheets or laminating metal foils. The absorption capacity was insufficient.

JP-A-9-93034 JP-A-2005-251918 JP 2005-101474 A JP 2006-93414 A JP 2006-60008 JP 2006-295101 A JP 2008-186997 A JP 2008-118116 A JP 2010-80911

As described above, the conventional noise absorbing articles have problems in usability, noise absorbing ability, and the like.
Accordingly, it is an object of the present invention to provide a noise absorbing fabric that is less likely to reflect electromagnetic waves and has excellent noise absorbing ability. Another object of the noise absorbing effect is to provide a noise absorbing fabric that is effective in a wider band.
Another object of the present invention is to provide a noise-absorbing fabric that is soft, flexible, thin, and can be incorporated into an intricate portion such as an electronic component or a case by bending or folding.
Furthermore, an object of the present invention is to provide a noise-absorbing fabric that can be produced easily and stably without using an expensive soft magnetic material, and that is inexpensive and has high performance.

As a result of intensive studies to solve the above-mentioned problems, the present inventor is a noise-absorbing fabric in which a conductive polymer is attached to the fibers of the fabric, and the surface resistance of at least one surface of the noise-absorbing fabric is as follows. It has been found that the above problems can be solved by a noise absorbing fabric characterized in that the common logarithm of the rate is in the range of 0 to 4, and the present invention has been completed.
Specifically, the present invention relates to the following aspects.

[Aspect 1]
A noise absorbing fabric in which a conductive polymer is attached to the fabric fibers,
The common logarithm of the surface resistivity of at least one surface of the noise absorbing fabric is in the range of 0 to 4,
The noise absorbing fabric.

[Aspect 2]
The noise-absorbing fabric according to aspect 1, formed by coating a fabric with a conductive polymer solution, or coating the fabric with a conductive polymer precursor and polymerizing the precursor.
[Aspect 3]
The noise absorbing fabric according to aspect 1 or 2, wherein the fabric is a nonwoven fabric made of synthetic long fibers.

[Aspect 4]
The noise absorbing fabric according to any one of aspects 1 to 3, wherein the fabric includes fibers having a fiber diameter of 7.0 μm or less.
[Aspect 5]
The fabric is a laminated fabric having at least two layers of a first layer and a second layer, the first layer is a nonwoven fabric layer made of fibers having a fiber diameter of 10 to 50 μm, and the second layer The noise-absorbing fabric according to any one of aspects 1 to 4, wherein the layer is a nonwoven fabric layer composed of fibers having a fiber diameter of 0.01 to 7.0 µm.

[Aspect 6]
The cloth is a laminated cloth having at least three layers of a first layer, a second layer, and a third layer in that order, and the first layer and the third layer have a fiber diameter of 10 to 50 μm. The noise absorption according to any one of aspects 1 to 5, wherein the second layer is a non-woven layer made of fibers having a fiber diameter of 0.01 to 7.0 μm. Fabric.

[Aspect 7]
The noise according to any one of aspects 1 to 4, wherein the fabric is a fabric in which fibers having a fiber diameter of 10 to 50 µm and fibers having a fiber diameter of 0.01 to 7.0 µm are mixed. Absorbent fabric.
[Aspect 8]
The noise-absorbing fabric according to any one of aspects 1 to 7, wherein the fabric has a thickness of 10 to 200 µm and a basis weight of 7 to 150 g / m ² .

[Aspect 9]
The noise-absorbing fabric according to any one of aspects 1 to 8, which is calendered.
[Aspect 10]
The noise absorbing fabric according to any one of aspects 1 to 9, wherein the return loss (S11) at 1 GHz is 0.2 or less.

[Aspect 11]
The noise-absorbing fabric according to any one of aspects 1 to 10, wherein the average aperture diameter is 0.5 μm to 5.0 mm.
[Aspect 12]
The noise absorbing fabric according to any one of aspects 1 to 11, wherein the conductive polymer is selected from the group consisting of an aniline polymer, a thiophene polymer, and a pyrrole polymer.

The noise absorbing fabric of the present invention is less likely to reflect electromagnetic waves and is excellent in noise absorbing ability. It is also effective for broadband noise.
The noise absorbing fabric of the present invention is also soft, flexible and thin, and can be incorporated into an intricate part such as an electronic component or a case by bending or folding.
Furthermore, the noise absorbing fabric of the present invention can be produced easily and stably without using an expensive soft magnetic material, and is inexpensive and has high performance.

FIG. 1 is a schematic view of a cross section of the noise absorbing fabric of the present invention. FIG. 2 is an enlarged schematic view of one cross section of an embodiment of the noise absorbing fabric of the present invention. FIG. 3 is a diagram for explaining the gradient in the thickness direction of the conductivity of the noise absorbing fabric of the present invention. FIG. 4 is a cross-sectional view of a noise absorbing fabric for explaining a cluster of conductive polymer. FIG. 5 is a schematic view showing a conductive polymer on a fiber formed by a gravure printing method. FIG. 6 is a diagram for explaining the microstrip line method. FIG. 7 is a diagram showing the measurement results of the noise absorbing fabric 1 obtained in Example 1 by the microstrip line method. FIG. 8 is a diagram showing the measurement result of the noise absorbing fabric 18 obtained in Example 18 by the microstrip line method. FIG. 9 is a diagram showing the measurement results of the noise absorbing fabric 25 obtained in Example 25 by the microstrip line method. FIG. 10 is a diagram showing measurement results of the comparative sheet 1 obtained in Comparative Example 1 by the microstrip line method.

Hereinafter, the noise absorbing fabric of the present invention will be specifically described.
In the noise absorbing fabric of the present invention, a conductive polymer is attached to the fabric fibers.
FIG. 1 is a schematic view of a cross section of the noise absorbing fabric of the present invention. A noise absorbing fabric 1 shown in FIG. 1 includes a fabric 2 and a conductive polymer 3 attached to the fabric.

FIG. 2 is an enlarged schematic view of one cross section of an embodiment of the noise absorbing fabric of the present invention. A noise absorbing fabric 1 shown in FIG. 2 includes a fabric 2 and a conductive polymer 3, and the conductive polymer 3 is attached to the fibers 4 constituting the fabric 2.
In FIG. 2, in order to help understanding, all the fibers are described so as to be oriented from the front of the paper to the back, and all the cross sections of the fibers are represented by a perfect circle.

In the noise absorbing fabric of the present invention, the common logarithm of the surface resistivity (Ω / □) of at least one surface of the noise absorbing fabric is in the range of 0-4. The common logarithm of surface resistivity means the value of log ₁₀ X where the surface resistivity is X (Ω / □). If the common logarithmic value of the surface resistivity is less than 0, the conductivity is too high, and most of the electromagnetic wave is reflected at the surface, and the noise absorption may be inferior. When the conductivity is small and the reflection of electromagnetic waves is large, interference between electromagnetic waves occurs, and noise absorption is inhibited.

  On the other hand, when the common logarithm value of the surface resistivity is more than 4, the electromagnetic wave may pass through the noise absorbing cloth and the electromagnetic wave absorption ability (capturing ability) may be inferior. When the common logarithm of the surface resistivity is in the range of 0 to 4, the electromagnetic wave appropriately enters the inside of the noise absorbing fabric of the present invention, and the electromagnetic wave that has entered the conductive material attached to the fiber. Since it is trapped by the conductive polymer, converted into electricity, and further converted into thermal energy by the electrical resistance of the conductive polymer, the noise absorbing ability is increased. The common logarithm of the surface resistivity of the noise absorbing fabric is preferably in the range of 0.1-3.

In the noise absorbing fabric of the present invention, the surface having a common logarithmic value of the surface resistivity in the range of 0 to 4 varies depending on the method of forming the conductive polymer, for example, as shown in FIG. 1 and FIG. In the embodiment, the upper surface of the noise absorbing fabric 1 can have the surface resistivity.
The surface resistivity can be measured by a four-terminal method using a low resistance meter Loresta-GP, model MCP-T600 manufactured by Mitsubishi Chemical Corporation.

The noise absorbing fabric preferably has a lower electrical conductivity inside the thickness direction than the surface of the noise absorbing fabric. As an example for making the internal conductivity in the thickness direction smaller than the electrical conductivity of the surface, the ratio of the conductive polymer in the thickness direction of the noise-absorbing fabric of the present invention to the fabric is calculated as follows. For example, the ratio may be lower than the ratio of the polymer to the fabric.
In the present specification, the term “fabric” refers to a fabric itself that does not include a conductive polymer, but the term “noise absorbing fabric” refers to a combination of the fabric itself and the conductive polymer. Means including both.

FIG. 3 is a diagram for explaining the gradient in the thickness direction of the conductivity of the noise absorbing cloth of the present invention, and is a schematic diagram in which the cross section of the noise absorbing cloth is enlarged. In FIG. 3, the vertical direction corresponds to the thickness direction of the noise absorbing fabric, and the lower portion in the thickness direction of the noise absorbing fabric is omitted.
A noise absorbing fabric 1 shown in FIG. 3 includes a fabric 2 formed from fibers 4 and a conductive polymer 3. In the noise absorbing fabric 1 shown in FIG. 3, the ratio of the conductive polymer in the interior (lower) to the fabric is lower than the ratio of the conductive polymer in the surface (upper) to the fabric. Therefore, in the noise absorbing fabric 1 of FIG. 3, the conductivity in the inside in the thickness direction is smaller than the surface thereof.

In FIG. 3, in order to help understanding, all the fibers are described so as to be oriented from the front to the back of the page, and the cross sections of the fibers are all represented by perfect circles.
Due to the moderate gradient of conductivity, electromagnetic waves that enter from the outside are captured and converted into current by the portion with high conductivity, but the electrical conductivity is particularly small in the interior, that is, the electrical resistance value is large. It becomes easy to be converted into thermal energy by resistance. Thereby, electromagnetic waves can be efficiently absorbed and noise can be absorbed.
The conductivity gradient can be achieved, for example, by printing a conductive polymer on one surface of the fabric by a gravure printing method described later.

In the noise absorbing fabric of the present invention, it is preferable that the conductivity in the thickness direction is smaller than the conductivity on the surface on at least one surface of the noise absorbing fabric, and the conductivity on the surface on both surfaces of the noise absorbing fabric. It is more preferable that the conductivity inside the thickness direction is smaller.
That the conductivity in the thickness direction is smaller than the conductivity on the surface on both sides of the noise absorbing fabric is achieved by, for example, printing a conductive polymer on both sides of the fabric by gravure printing. Can do.

  In the noise absorbing fabric of the present invention, a fabric that is an aggregate of fibers is employed as a base material. By adopting a fabric as a base material, it is more flexible and flexible, and can be formed into a more complex shape when incorporated in an electronic device, and has a high degree of integration in the housing of the electronic device. It can arrange | position in the location where the noise of an electronic component generate | occur | produces.

  Further, by employing a fabric that is an aggregate of fibers as a base material, the noise absorbing fabric can include a plurality of clusters of conductive polymers. FIG. 4 is a cross-sectional view of a noise absorbing fabric for explaining a cluster of conductive polymer. The noise absorbing fabric 1 shown in FIG. 4 includes a fabric 2 and a conductive polymer 3, and the conductive polymer 3 is composed of a plurality of conductive polymer clusters 5. Each of the conductive polymer clusters 5 is electrically connected to other clusters at a place other than the cross section, that is, at any place different in the height direction with respect to the paper surface to form a huge network, Because it has a switch effect, it has a high noise absorption capability. Reference numeral 5 'in FIG. 4 indicates an electrical contact of each cluster.

  In addition, since the surface of the fabric is not smooth, when a conductive polymer is coated on the surface of the fabric by a gravure printing method or the like, a gradient is generated in the amount of the coated conductive polymer, and when viewed microscopically, depending on the location, The resistance value will be different. Therefore, electromagnetic waves that enter from the outside are captured by a conductive polymer having a certain conductivity and electrical resistance value, converted into an electric current, and then converted into thermal energy by an electrical resistance, thereby exhibiting its noise absorption. Is done. This point is greatly different from those having a smooth surface such as a conventional film or sheet.

That is, when a smooth surface such as a film or sheet is coated with a conductive polymer by a gravure printing method or the like, a smooth conductive polymer layer is formed, and the large conductivity of the conductive polymer is exerted. The common logarithm of resistivity is likely to be less than 0, and electromagnetic waves are likely to be reflected.
In addition, it is difficult to process the surface of films, sheets, etc. in a non-uniform manner.

  The fabric used in the present invention is an aggregate of fibers, has many entanglement points between fibers, and its surface is non-uniform (having a curvature when viewed from one direction). For example, gravure printing When the conductive polymer is coated on the cloth by a method such as the above, a more electrically non-uniform conductive polymer layer is formed, and once captured electromagnetic waves are more efficiently consumed by the electric resistance. Therefore, the noise absorbing cloth of the present invention Can have a very high noise absorption capability.

The fabric used in the present invention is preferably a non-woven fabric, and the fibers forming the fabric are preferably synthetic long fibers.
In general, in a woven fabric, a knitted fabric, and the like, since the ratio of fibers oriented in the thickness direction and / or the planar direction of the fabric is high, a noise absorbing fabric formed from a fabric such as a woven fabric, a knitted fabric is electrically conductive. The polymer is oriented in the same direction as the fiber and has directionality in noise absorption. Therefore, a noise absorbing fabric formed from a fabric such as a woven fabric or a knitted fabric is useful when absorbing noise having a specific direction.

On the other hand, in the nonwoven fabric, since the fibers are often not oriented in the thickness direction and the plane direction of the nonwoven fabric, the noise-absorbing fabric formed from the nonwoven fabric does not have the orientation as the fibers and absorbs noise. It is difficult to have directionality. In general electronic devices, noise is generated from various places and the directionality of the noise is often small. Therefore, for general electronic devices, a noise absorbing fabric using a non-woven fabric as a fabric is preferable.
In addition, the smaller the orientation of the conductive polymer, the lower the ratio of reflecting the noise that has reached the noise absorbing fabric in a specific direction, so that higher noise absorption can be exhibited. Therefore, from the above viewpoint, a noise absorbing fabric employing a nonwoven fabric as the fabric is preferable.

  The fabric used for the noise absorbing fabric of the present invention is preferably a fabric formed by heat. This is because in the case of a fabric formed by adding a binder, the binder may shift to an electronic device and cause the device to malfunction. Moreover, it is preferable that it is the fabric formed with the heat | fever from a viewpoint of cost.

  The fabric used for the noise absorbing fabric of the present invention is more preferably a fabric made of synthetic long fibers formed by heat. When used in electronic equipment, the noise absorbing fabric of the present invention is punched into a complicated shape depending on the shape of an electronic component, the shape of a circuit line, etc., and is affixed to an electronic component, a transmission line, or the like. It can be used by being cut to size and affixed to the casing of electronic components, etc., in order to prevent the fiber pieces with the conductive polymer attached from short-circuiting and malfunctioning the electronic device. It is.

In the present invention, the fibers constituting the fabric are preferably synthetic fibers capable of forming the fabric by heat. Chemical fibers such as highly hydrophilic pulp and rayon fiber are not preferable because they tend to contain moisture and cause malfunction of electronic devices.
Specific examples of fibers constituting the fabric used in the present invention include polyolefins such as polypropylene and polyethylene, polyalkylene terephthalate resins (PET, PBT, PTT, etc.) and derivatives thereof, polyamide resins such as N6, N66, and N612, and Examples thereof include fibers formed from derivatives thereof, polyoxymethylene ether resins (such as POM), PEN, PPS, PPO, polyketone resins and polyketone resins such as PEEK, thermoplastic polyimide resins such as TPI, and combinations thereof. It is done.

Although the said fiber can be suitably selected according to the environment where the noise absorption fabric of this invention is applied, it can be selected as follows, for example.
Since polyamide resins such as N6, N66, and N612 and their derivatives are resins having a high water absorption rate, it is desirable to avoid application to electronic components that are extremely hated of moisture compared to other resins. When solder heat resistance is required or when there is a possibility of malfunction due to heat from electronic parts, for example, in electronic devices that require heat resistance, PET resin, PPS resin, PEEK resin, etc. It is preferred to use fibers formed from On the other hand, judging from electrical characteristics such as dielectric constant and tan δ, polyolefin resin, PET resin, PPS resin, PPO resin, PEEK resin and fluorine resin are preferable.

The fiber is preferably a flame retardant fiber. This is because, from the viewpoint of safety of electronic components, fibers that are difficult to burn due to ignition should be adopted.
Although the fiber diameter of the said fiber changes with the environment where the noise absorption fabric of this invention is applied, generally it is preferable that a fiber diameter is 50 micrometers or less. This is because a fabric having a uniform inter-fiber distance can be obtained, and leakage of electromagnetic waves, for example, transmission can be reduced. Further, if the fiber diameter is 50 μm or less, the fiber has high strength and can be stably processed and used without breaking the fabric or noise absorbing fabric in the process of attaching the conductive polymer, the environment in which it is used, etc. Etc.

  In the noise absorbing fabric of the present invention, it is preferable that the fabric includes a fiber having a fiber diameter of 7.0 μm or less (hereinafter, sometimes referred to as “extra fine fiber”). By including ultrafine fibers, the number of fabric fibers per fixed volume is increased, and when the specific surface area of the fibers is increased, the specific surface area of the conductive polymer is also increased and the noise absorbing ability is further increased. In addition, since the noise absorbing fabric can be made thin by including ultrafine fibers, it is suitable for electronic devices that aim to be light and thin. In addition, since the noise absorbing fabric can be flexibly bent by being thin, it is easy to be attached to an electronic device and the noise absorbing ability is more easily exhibited. The ultrafine fiber preferably has a fiber diameter of 4.0 μm or less. The fiber diameter of the ultrafine fiber is preferably 0.01 μm or more, and more preferably 0.05 μm or more.

  Since the cloth containing the above-mentioned ultrafine fibers tends to decrease in strength, it is preferably used in combination with fibers having a fiber diameter larger than that of the ultrafine fibers. Examples of the combined use include a laminated fabric in which layers of fabrics having different fiber diameters are laminated, a single type fabric in which a plurality of fibers having different fiber diameters are mixed, a combination thereof, and the like.

  The laminated fabric is a laminated fabric having at least two layers of a first layer and a second layer, and the first layer is a fiber having a fiber diameter of 10 to 50 μm (hereinafter referred to as “general fiber”). And the second layer is a non-woven layer made of fibers having a fiber diameter of 0.01 to 7.0 μm. In addition, the laminated fabric is a laminated fabric having at least three layers of the first layer, the second layer, and the third layer in the order of the first layer, the second layer, and the third layer, The first layer and the third layer are nonwoven fabric layers made of fibers having a fiber diameter of 10 to 50 μm, and the second layer is a fabric layer made of fibers having a fiber diameter of 0.01 to 7.0 μm. Some are listed as preferred embodiments.

  Examples of the laminated fabric include four or more layers. A nonwoven fabric layer composed of fibers having a fiber diameter of 10 to 50 μm is designated as “S”, and a fiber having a fiber diameter of 0.01 to 7.0 μm. When the non-woven fabric layer is “M”, SMMS, SMMMS, etc., the first layer and the lowermost layer are S, and a plurality of M are stacked between them.

The method for producing the ultrafine fiber is not particularly limited, but a melt blown method and an electrospinning method are preferable, and a melt blown method is more preferable.
The cross-sectional shape of the fiber including the ultrafine fiber is not particularly limited, but it is preferable to employ an atypical yarn, a split yarn, or the like in order to form a more uneven surface. For the same purpose, crimp yarn, twisted yarn or the like can be employed.

The fabric used in the present invention preferably has a tensile strength of about 10 N / 3 cm or more and about 20 N / 3 cm or more in consideration of the process of attaching the conductive polymer, the strength necessary for the noise absorbing fabric at the time of use, and the like. More preferably, it has a tensile strength. When the tensile strength is less than about 10 N / 3 cm, there are cases where the fabric breaks or wrinkles when coating the conductive polymer by gravure printing or the like, and breaks during use. There is a case.
In the above tensile strength, “/ 3 cm” means that the width of the test piece is 3 cm, and “5.3” in JIS L1906: 2000, except that the size of the sample is 3 cm × about 30 cm. It can be measured according to “5.3.1 Standard time” of “Tensile strength and elongation”.

The thickness of the fabric used in the present invention is preferably in the range of about 10 to about 200 μm, and more preferably in the range of about 15 μm to about 150 μm. When the thickness of the fabric is less than about 10 μm, for example, when coating the conductive polymer on the fabric, there is a case where the coating does not have an appropriate strength and waist and may be difficult to coat. And the strength of the formed noise absorbing fabric may be weak. Further, when the thickness of the fabric exceeds about 200 μm, for example, when the conductive polymer is coated on the fabric, the waist may become excessively strong, and the formed noise absorbing fabric is too thick, and the narrow portion May be difficult to insert, bend, fold, and difficult to attach to electronic components.
The thickness of the fabric can be measured according to the method defined in “5.1 Thickness” of “5. Method” of JIS L-1906: 2000.

The basis weight of the fabric used in the present invention is preferably in the range of about 7 to about 150 g / m ² , and more preferably in the range of about 15 to about 100 g / m ² . When the basis weight is less than about 7 g / m ² , for example, when the conductive polymer is coated on the fabric, the conductive polymer may penetrate through and contaminate the device. Furthermore, the noise-absorbing fabric of the present invention is weak and may break during processes such as processing and punching. When the basis weight is more than about 150 g / m ² , the noise-absorbing fabric of the present invention may be excessively heavy. When the basis weight is in the range of about 7 to about 150 g / m ² , the noise-absorbing fabric of the present invention can maintain its shape and handleability is also good.
The basis weight can be measured according to the method defined in “5.2 Mass per unit area” of “5. Method” of JIS L-1906: 2000.

  The fabric used in the present invention preferably has an average pore diameter of about 0.5 μm to about 5.0 mm, more preferably an average pore diameter of about 0.5 μm to about 3.0 μm. More preferably, it has an average aperture size of 5 μm to about 1.0 mm, even more preferably an average aperture size of about 0.5 μm to about 500 μm, and an average aperture size of about 0.5 μm to about 200 μm. Most preferred.

If the average pore diameter is less than about 0.5 μm, the gap is too small, the distance between the conductive polymer layers is not adequately separated, and current flow is not hindered. Further, the fibers are not separated appropriately, that is, the entanglement points between the fibers are not increased, and the noise absorption is not increased by the switching effect. On the other hand, when the average pore diameter is more than about 5.0 mm, the gap is too large. For example, when the conductive polymer is coated on the fabric, the conductive polymer cannot be uniformly coated, and the desired electric resistance is not obtained. It becomes difficult to obtain a value. In addition, when the conductive polymer is coated on the fabric, the equipment may be defective. Moreover, when an average hole diameter is about 1.0 mm or less, the entanglement point of fibers will increase and the noise absorptivity can be made higher by the switching effect.
The average pore diameter can be measured by the method described in the examples.

  In the fabric used for this invention, the manufacturing method in particular is not restrict | limited, It can manufacture by various manufacturing methods. Moreover, it is preferable that the fabric is calendered so that the fabric has an appropriate surface structure. By calendering, the fabric has moderate irregularities on the surface, and therefore, after the conductive polymer is adhered, good conductivity can be obtained, and an appropriate surface resistance value can be easily obtained.

  In the noise absorbing fabric of the present invention, “the conductive polymer is attached to the fiber of the fabric” means that the conductive polymer is present on the surface and / or inside of the fabric fiber. Coating method, for example, gravure printing using a conductive polymer solution, for example, a conductive polymer dispersion aqueous solution in which fine particles of a polymer in which a polymer and a dopant are bonded, or a conductive polymer solution is used. Method, screen printing method, bar coating method, Dip-Nip method, or polymerization method, for example, impregnating a fabric with a monomer that is a precursor of a conductive polymer together with an oxidizing agent, an oxidation polymerization catalyst, etc., and performing polymerization. Examples thereof include a polymerization method.

  As the physical coating method, a gravure printing method and a screen printing method are preferable. This is because it is easy to form a conductivity gradient between the surface and the inside by coating the fabric with the conductive polymer while controlling the basis weight of the conductive polymer from one side of the fabric. In addition, since the cross section of the fiber is circular, coating the conductive polymer on the fabric by gravure printing or screen printing causes a distribution in the thickness of the conductive polymer on the individual fibers. Is preferable.

  FIG. 5 is a schematic view showing a conductive polymer on a fiber formed by a gravure printing method. In FIG. 5, when gravure printing is performed from above, the conductive polymer 3 is formed on the fiber 4, but the thickness of the conductive polymer 3 varies depending on the location. In this case, the coated conductive polymer 3 was trapped because the thick portion and the thin portion had different electromagnetic wave capturing properties and had spots when observed from the viewpoint of electrical resistance. When electromagnetic waves become current and flow through the above portion, they are expected to change to thermal energy due to electrical resistance and to increase noise absorption ability.

  In the present invention, the conductive polymer attached to the fiber of the fabric is not particularly limited as long as it has conductivity. For example, an aniline polymer, a thiophene polymer, a pyrrole polymer, a phenylene vinylene polymer, Examples thereof include phenylene sulfide-based polymers.

  Specific examples of the conductive polymer include aniline polymers such as polyaniline, poly (2-methylaniline), poly (3-isobutylaniline), poly (2-anilinesulfonic acid), and poly (3-anilinesulfonic acid). ), Etc., such as polythiophene, poly (3-methylthiophene), poly (3-ethylthiophene), poly (3-propylthiophene), poly (3-butylthiophene), poly (3-hexylthiophene) , Poly (3-heptylthiophene), poly (3-octylthiophene), poly (3-decylthiophene), poly (3-dodecylthiophene), poly (3-octadecylthiophene), poly (3-bromothiophene), poly (3-chlorothiophene), poly (3-iodothiophene), poly (3- Anothiophene), poly (3-phenylthiophene), poly (3,4-dimethylthiophene), poly (3,4-dibutylthiophene), poly (3-hydroxythiophene), poly (3-methoxythiophene), poly ( 3-ethoxythiophene), poly (3-butoxythiophene), poly (3-hexyloxythiophene), poly (3-heptyloxythiophene), poly (3-octyloxythiophene), poly (3-decyloxythiophene), Poly (3-dodecyloxythiophene), poly (3-octadecyloxythiophene), poly (3-methyl-4-methoxythiophene), poly (3,4-ethylenedioxythiophene), poly (3-methyl-4- Ethoxythiophene), poly (3-carboxythiophene), poly (3-methyl 4-carboxythiophene), poly (3-methyl-4-carboxyethylthiophene), poly (3-methyl-4-carboxybutylthiophene), etc., pyrrole polymers such as polypyrrole, poly (N-methylpyrrole), poly (3-methylpyrrole), poly (3-ethylpyrrole), poly (3-n-propylpyrrole), poly (3-butylpyrrole), poly (3-octylpyrrole), poly (3-decylpyrrole), poly (3-dodecylpyrrole), poly (3,4-dimethylpyrrole), poly (3,4-dibutylpyrrole), poly (3-carboxypyrrole), poly (3-methyl-4-carboxypyrrole), poly (3 -Methyl-4-carboxyethylpyrrole), poly (3-methyl-4-carboxybutylpyrrole), poly (3-hydroxy Droxypyrrole), poly (3-methoxypyrrole), poly (3-ethoxypyrrole), poly (3-butoxypyrrole), poly (3-methyl-4-hexyloxypyrrole), etc., phenylene vinylene-based polymers, for example, Poly (p-phenylene vinylene), poly (2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylene vinylene, and the like, as well as phenylene sulfide polymers such as poly (p-phenylene sulfide), and polyaniline Polythiophene and poly (3,4-dioxythiophene) polypyrrole are preferable from the viewpoint of easy control of conductivity because of their high conductivity.

  The fabric used in the present invention is not particularly limited, and general woven fabrics, knitted fabrics, nonwoven fabrics and the like can be employed. Examples of the fabric used in the present invention include a nonwoven fabric composed of synthetic long fibers, a nonwoven fabric composed of short fibers formed by a papermaking method, a dry method, etc., formed by a spunbond method, a melt blown method, a flash spinning method, or the like. Can be mentioned. Nonwoven fabrics formed from synthetic fibers are preferred because of their high strength, excellent processability, and excellent handling of noise absorbing fabrics.

  Further, as the fabric used in the present invention, a laminated nonwoven fabric formed by laminating a nonwoven fabric layer made of ultrafine fibers and a nonwoven fabric layer made of general fibers is preferable. The ultrafine fibers and the general fibers are preferably made of a thermoplastic resin, and the non-woven fabric layer made of ultrafine fibers and the non-woven fabric layer made of general fibers are integrated with heat embossing to obtain a tensile strength of the laminated non-woven fabric. And bending flexibility can be maintained, and heat stability can be maintained. Examples of the laminated nonwoven fabric include those produced by laminating a layer of a spunbond nonwoven fabric, a layer of a meltblown nonwoven fabric, and a layer of a spunbond nonwoven fabric in that order, and then pressing with an embossing roll or a hot press roll.

As the laminated nonwoven fabric, at least one spunbond nonwoven fabric layer is spun on a conveyor using a thermoplastic synthetic resin, and then a nonwoven fabric of ultrafine fibers by a melt blown method using the thermoplastic synthetic resin thereon. At least one layer is sprayed. Then, the laminated nonwoven fabric manufactured by integrating by crimping using an embossing roll or a flat roll is preferable.
Further, at least one thermoplastic synthetic long fiber nonwoven fabric using a thermoplastic synthetic resin is laminated on the meltblown nonwoven fabric before thermocompression bonding, and then integrated by crimping using an emboss roll or flat roll. The laminated nonwoven fabric manufactured by this is more preferable.

  In the above laminated nonwoven fabric, the layer of the ultrafine fiber nonwoven fabric by the melt blown method is directly sprayed on the layer of the thermoplastic synthetic long fiber nonwoven fabric. It can be penetrated into the non-woven fabric layer, and the fiber gap of the non-woven fabric layer of thermoplastic synthetic long fibers can be filled. In this way, since the ultrafine fibers penetrate into the nonwoven fabric of the thermoplastic synthetic long fiber and are fixed by the melt-blown method, not only the strength of the laminated nonwoven fabric structure itself is improved, but also the layer of the ultrafine fiber nonwoven fabric. Since the movement due to the external force is less likely to occur, delamination is difficult. The manufacturing method of the said laminated nonwoven fabric is disclosed by international publication 2004/94136 pamphlet, international publication 2010/126109, etc.

In the case of a laminated nonwoven fabric in which a spunbond nonwoven fabric layer and a meltblown nonwoven fabric layer are laminated, the basis weight of the spunbond nonwoven fabric layer is aligned vertically for both the 3 layers laminated nonwoven fabric and the 2 layers laminated nonwoven fabric. About 1.0 to about 270 g / m ² , the basis weight of the meltblown nonwoven layer is about 0.3 to about 270 g / m ² , and the total basis weight is about 7 to about 300 g / m ² Preferably there is. The basis weight of the spunbond nonwoven fabric layer is about 3.0 to about 100 g / m ² , the basis weight of the meltblown nonwoven fabric layer is about 0.5 to about 120 g / m ² , and the total basis weight Is more preferably about 15 to about 150 g / m ² .

  The noise absorbing capacity of the noise absorbing fabric of the present invention is clearly different from the above-described conventional technology, and the noise absorbing fabric of the present invention has a high magnetic permeability. Even if it has almost no value, it can exhibit high noise absorption ability. The noise absorbing fabric of the present invention exhibits noise absorbing ability due to the gradient of conductivity. As described above, by attaching the conductive polymer to the fiber of the fabric including the ultrafine fibers, the surface area of the conductive polymer is increased, and the noise absorption capability is increased.

  In the noise absorbing fabric of the present invention, the following matters can be mentioned as advantages of using a conductive polymer having no magnetism. For example, magnetic sensors, electronic compasses, CDs, DVDs, and the like are examples of devices used in recent years for electronic devices, but magnetic sensors and electronic compass cannot be used together. In addition, in devices (pickup devices) that read and write information from magnetic storage media such as CDs and DVDs, storage is performed depending on the presence or absence of magnetism, and most of the pickup devices that read this perform magnetic reading. In this apparatus, if there is an object having magnetism in the vicinity, reading failure is likely to occur. For this reason, the noise absorbing sheet containing soft magnetic particles, magnetic particles, etc., which has been used in recent years, could not be used in these devices, but the noise absorbing fabric containing a conductive polymer having no magnetism. Can be used in the above apparatus.

  The noise-absorbing fabric of the present invention can be subjected to the following treatment on one side or both sides in order to put it to practical use in an electronic device or the like. For example, an insulation process can be performed in order to prevent a short circuit. Specifically, resin coating, resin lamination, insulating film lamination, and the like can be performed. In addition, it is possible to perform processing for imparting adhesiveness so as to stick to the electronic device, installation of screws, screw holes, and the like for setting in the casing of the electronic device. A treatment for imparting adhesiveness for bonding to an electronic device is preferable because fixing to the electronic device becomes easier.

  The noise absorbing fabric of the present invention can be applied to electronic devices and the like as described below to absorb noise. For example, it can be affixed to electronic components such as LSI, and can be affixed to a circuit such as a glass epoxy substrate, FPC, or the back surface thereof, on a transmission line on the circuit, on a part where the electronic component is mounted on the circuit, etc. Can be affixed, and can be affixed to the connector part, a cable that connects to other devices, parts, etc. from the connector, or can be affixed to the case, the back of the holding body, or the front of the electronic component / device It can be wound around a power line, a transmission line cable, or the like.

  In consideration of ease of use, if desired, an adhesive layer (hot melt adhesive, general adhesive, etc.) can be provided on the front or back for bonding to the above electronic equipment, etc. When an electrical insulation layer is required, an electrical insulation layer (a film laminate, a polymer laminate layer can be provided on the front or back of the electronic device, etc., and an electrical insulation layer is formed by combining with other insulating materials, etc. Can be provided).

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further, this invention is not limited to these Examples at all.
The measurement method and evaluation method are as follows.

[(1) Microstrip line (MSL) method]
The measurement was performed by the microstrip line method in accordance with IEC standard 62333-2. As shown in FIG. 6, the measurement was performed by the S-parameter method using a microstrip line fixture 6 (manufactured by Microweb Factory) having an impedance of 50Ω and a network analyzer 8 (model N5230C manufactured by Agilent Technologies). The size of the sample 7 of the noise absorbing fabric was 5 cm × 5 cm, and this was placed on the microstrip line fixture 6 and measured. In FIG. 6, reference numeral 9 denotes a microstrip line.
The S parameter reflection attenuation (S11) and transmission attenuation (S21) were measured at each frequency, and the loss rate was calculated from the following equation (1).
Loss rate (Ploss / Pin) = 1− (S11 ² + S21 ² ) / 1 Formula (1)

[(2) Surface resistivity]
Using a low resistance meter Loresta-GP, model MCP-T600 manufactured by Mitsubishi Chemical Corporation, the measurement was performed by a four-terminal method. In the measurement, n = 3 and the average value was adopted.

[(3) Average pore diameter (μm)]
PMI palm porometer (model: CFP-1200AEX) was used. Using Sylwick manufactured by PMI as the immersion liquid, the sample was immersed in the immersion liquid and sufficiently deaerated, and measurement was performed.
In this measuring device, the filter is immersed in a liquid with a known surface tension in advance, and pressure is applied to the filter from a state in which all pores of the filter are covered with a liquid film. The pore diameter calculated from the tension is measured. The following formula (2) was used for calculation of the average pore diameter.
d = C × r / P Formula (2)
(Where d (unit: μm) is the pore diameter of the filter, r (unit: N / m) is the surface tension of the liquid, and P (unit: Pa) is the liquid film with the pore diameter destroyed. Pressure, and C is a constant.)

  When the flow rate (wetting flow rate) when the pressure P applied to the filter immersed in the liquid is continuously changed from low pressure to high pressure is measured, the liquid film with the largest pores is not destroyed at the initial pressure, so the flow rate is 0. As the pressure is increased, the liquid film with the largest pores is destroyed and a flow rate is generated (bubble point). When the pressure is further increased, the flow rate increases in accordance with each pressure, and the liquid film with the smallest pores is destroyed, which coincides with the dry flow rate (dry flow rate).

In this measuring apparatus, a value obtained by dividing the wetting flow rate at a certain pressure by the dry flow rate at the same pressure is referred to as a cumulative filter flow rate (unit:%). Moreover, the pore diameter of the liquid film destroyed at a pressure at which the cumulative filter flow rate becomes 50% was referred to as the average flow pore size, and this was used as the average pore size of the fabric used in the present invention.
In the present specification, the maximum pore diameter is the range of −2σ in which the cumulative filter flow rate is 50%, that is, the cumulative filter flow rate is 2.3%. did.

[(4) Basis weight of fabric]
The basis weight of the fabric was determined in accordance with the method specified in “5.2 Mass per unit area” of “5. Method” of JIS L-1906: 2000. Samples were collected and measured for mass, and the average value was calculated by converting to mass per unit area.

[(5) Fabric thickness]
According to the method specified in “5.1 Thickness” of “5. Method” of JIS L-1906: 2000, the thicknesses at 10 locations per 1 m width were measured, and the average value was used as the thickness of the fabric. The load was 9.8 kPa.

[(6) Diameter of fiber]
Average fiber diameter (μm): Obtained by arbitrarily picking up fibers from an electron micrograph and reading their diameter from the photograph. An arithmetic average value of n = 50 is adopted as the average fiber diameter.

[(7) Basis weight of conductive polymer]
The basis weight BW ₀ of the fabric before the conductive polymer adheres is measured according to the method described in “(4) Basis weight of fabric”. Next, the basis weight BW ₁ of the noise-absorbing fabric adhered to the fibers of the fabric is measured according to the method described in “(4) Basis weight of fabric”. The basis weight of the conductive polymer is calculated by subtracting BW ₀ from BW ₁ .

[(8) Bonding model test]
A double-sided tape is applied to the entire surface of one side of a 5 cm × 5 cm sample. Next, the remaining surface of the double-sided tape was affixed to a hemisphere of a ping-pong ball used in table tennis, and the state and ease of affixing were determined as follows.
A: Easy to apply and no defects were observed in the applied state.
○: Easy to apply, but some sample protrusions, wrinkles, sheet tears, etc. were observed.
Δ: Can be affixed, but as a whole, protrusions, wrinkles, and tearing of the sample were observed
X: It was very difficult to apply, and protrusions, wrinkles, and tearing of the sample were observed as a whole.

[Example 1]
The noise absorbing fabrics of Examples 1 to 19 were manufactured by the following method, and the noise absorbing ability was measured.
[Manufacture of conductive polymer]
144 g of aerosol OT (sodium diisooctylsulfosuccinate, purity 75% or more) manufactured by Wako Pure Chemical Industries, Ltd. was added to 4 L of toluene and stirred to dissolve the aerosol OT, and the aerosol OT was placed in a 30 L stirrer under a nitrogen stream. Then, 150 g of aniline was added to the solution, and the aniline was dissolved by stirring. The stirrer was cooled with a refrigerant, and 12 L of 1N hydrochloric acid was added to the stirrer.

  Next, in a state where the temperature of the solution in the stirrer was cooled to −3 ° C., a solution in which 214 g of ammonium persulfate was dissolved in 4 L of 1N hydrochloric acid was added dropwise to the stirrer with a dropping funnel over 3 hours and 10 minutes. From the start of dropping, the temperature of the solution in the stirrer was maintained at 0 ° C. ± 1 ° C. for 18 hours and 30 minutes with stirring. Next, 8 L of toluene was added to the stirrer, the solution temperature was raised to 19 ° C., and the mixture was allowed to stand. The aqueous phase (lower phase) of the solution separated into two phases by standing was withdrawn from the lower part of the stirrer to obtain a polyaniline-containing toluene solution.

  Next, 4 L of ion-exchanged water was added to the toluene solution, stirred, and allowed to stand to separate the aqueous phase. After performing this operation again, the toluene solution was similarly washed with 4 L of 1N hydrochloric acid aqueous solution, allowed to stand, the acidic aqueous solution was separated, and the toluene solution of polyaniline was recovered. Some insoluble matter contained in the toluene solution was removed with # 5C filter paper. Subsequently, the toluene solution was transferred to an evaporator, heated in a 60 ° C. hot water bath, and reduced in pressure to evaporate and remove volatile matter, whereby 208 g of polyaniline was obtained.

1 g of the above polyaniline was dissolved again in 18 mL of toluene, and then 2 mL of m-cresol was added to obtain a stock solution of the polyaniline solution. 99 mL of toluene was added to 1 mL of the stock solution of the polyaniline solution to prepare a polyaniline solution having a concentration of 0.5 g / L (see Patent Document: Japanese Patent Application Laid-Open No. 2007-73498).
Polyaniline was attached to E05050, a PET spunbond nonwoven fabric manufactured by Asahi Kasei Fibers using a gravure printing method. The gravure plate was adjusted so that the coating amount of the conductive polymer solution was 100 g / m ² . After gravure printing, the fabric was dried at 80 ° C. for 5 minutes to obtain a noise absorbing fabric 1. As a base material, Asahi Kasei Fibers PET spunbond nonwoven fabric, E05050 was used. The characteristics of the noise absorbing fabric 1 are shown in Table 1. Moreover, the measurement result by the microstrip line method of the noise absorption fabric 1 is shown in FIG.

[Examples 2 to 5]
In Examples 2 to 5, noise absorbing fabrics 2 to 5 were obtained by changing Example 1 and the gravure plate and changing the coating amount of the conductive polymer. Table 1 shows the characteristics of the noise absorbing fabrics 2 to 5.

[Examples 6 to 17]
In Examples 6 to 17, noise absorbing fabrics 6 to 17 were obtained according to Example 1 except that the fabrics were changed as shown below. The characteristics of the noise absorbing fabrics 6 to 17 are shown in Table 1.
Example 6: PU5040 (Material: Polypropylene, manufactured by Asahi Kasei Fiber)
Example 7: N05050 (Material: nylon 6, manufactured by Asahi Kasei Fiber)
Example 8: Precise AS030 (Material: PET, manufactured by Asahi Kasei Fibers)
Example 9: Precise AS080 (Material: PET, manufactured by Asahi Kasei Fibers)
Example 10: E05020 (Material: PET, manufactured by Asahi Kasei Fibers)
Example 11: E05030 (Material: PET, manufactured by Asahi Kasei Fibers)
Example 12: E05120 (Material: PET, manufactured by Asahi Kasei Fibers)
Example 13: Short fiber nonwoven fabric (wet nonwoven fabric: Pure Ali 040BC Material: PET, manufactured by Awa Paper Co., Ltd.)
Example 14: A short fiber nonwoven fabric (spun lace nonwoven fabric Sontara 8005 material: PET DuPont) was calendered and used.
Example 15: Meltblown nonwoven fabric E3008 (material: PET, manufactured by Asahi Kasei Fiber) was calendered and used.
Examples 16 and 17: Taffeta with ester yarn was used.

[Example 18]
A noise absorbing fabric 18 was produced according to the method described in Example 1, except that the fabric was changed to Presise AS030 (material: PET, manufactured by Asahi Kasei Fibers), the gravure plate was changed, and the coating amount was changed. The characteristics of the noise absorbing fabric 18 are shown in Table 1. Moreover, the measurement result by the microstrip line method of the noise absorption fabric 18 is shown in FIG.

[Example 19]
A conductive polymer was formed on the fabric by the chemical polymerization method described below. First, a solution containing 3,4-ethylenedioxythiophene as a monomer (1 part), ferric p-toluenesulfonate (2 parts) as an oxidizing agent, and normal butanol (4 parts) as a solvent In addition, Asahi Kasei Fiber PET spunbond nonwoven fabric, E05050 was dipped and pulled up, and then kept at 100 ° C. to promote polymerization and impregnate a conductive polymer of polyethylenedioxythiophene, a noise absorbing fabric 19 was obtained. The characteristics of the noise absorbing fabric 19 are shown in Table 1.

[Example 20]
A noise absorbing fabric 20 was obtained according to the method described in Example 19 except that the fabric was changed to Presise AS030 (material: PET, manufactured by Asahi Kasei Fibers). The characteristics of the noise absorbing fabric 20 are shown in Table 1.

[Example 21]
A noise absorbing fabric 21 was obtained according to Example 1 except that polyaniline was deposited by screen printing using a 200 mesh screen and the fabric was dried at 80 ° C. for 10 minutes. The characteristics of the noise absorbing fabric 21 are shown in Table 1.

[Examples 22 and 23]
For Examples 22 to 23, noise absorbing fabrics 22 and 23 were obtained according to the method described in Example 21 except that the screen mesh was changed to 150 and 100. The characteristics of the noise absorbing fabrics 22 and 23 are shown in Table 1.

[Examples 24-28]
In Examples 24-28, noise-absorbing fabrics 24-28 were obtained according to the method described in Example 21, except that the fabric was changed to the following. Table 1 shows the characteristics of the noise absorbing fabrics 24-28. Moreover, the measurement result by the microstrip line method of the noise absorption fabric 25 obtained in Example 25 is shown in FIG.
Example 24: Precise AS030 (Material: PET, manufactured by Asahi Kasei Fibers)
Example 25: Precise AS080 (material: PET, manufactured by Asahi Kasei Fibers)
Example 26: E05020 (Material: PET, manufactured by Asahi Kasei Fibers)
Example 27: Short fiber nonwoven fabric (spun lace nonwoven fabric Sontara 8005 material: PET DuPont) was calendered and used.
Example 28: Melt blown nonwoven fabric: E3008 (material: PET, manufactured by Asahi Kasei Fibers Co., Ltd.) was calendered and used.

[Example 29]
General-purpose polyethylene terephthalate is extruded by the spunbond method at a spinning temperature of 300 ° C so that the filament long fiber group faces the moving collection surface, and is spun at a spinning speed of 3500 m / min. The unbonded continuous fiber web (hereinafter, sometimes referred to as “web layer A”) having a uniformity of 5 cm fluctuation rate of 15% or less, consisting of filaments having an average fiber diameter of 12 μm, is sufficiently opened. Amount: about 7.5 g / m ² , formed on the collection net surface.

Next, polyethylene terephthalate (melt viscosity ηsp / c 0.50) was spun by a melt blown method under the conditions of a spinning temperature of 300 ° C., a heating air temperature of 320 ° C., and a discharge air of 1000 Nm ³ / hr / m, Ultrafine fibers having an average fiber diameter of 1.7 μm are directly ejected toward a long-fiber web formed as a random web (hereinafter sometimes referred to as “web layer B”) having a basis weight of about 5 g / m ^2. It was. The distance from the meltblown nozzle to the upper surface of the web layer A was 100 mm, and the suction on the collecting surface immediately below the meltblown nozzle was set to 0.2 kPa and the wind speed was about 7 m / sec.

On the surface of the web layer B opposite to the web layer A, a continuous fiber web of polyethylene terephthalate is opened in the same manner as the web layer A prepared first, and the web layer A / web layer B / web layer A A three layer laminated web was prepared.
Next, the three-layer laminated web was thermocompression-bonded between two flat rolls to obtain a three-layer laminated nonwoven fabric of nonwoven fabric layer A / nonwoven fabric layer B / nonwoven fabric layer A, and was formed first. Polyaniline was deposited on the nonwoven fabric layer A derived from the web layer A by a screen printing method using a 200 mesh screen, and the fabric was dried at 80 ° C. for 10 minutes to form a noise absorbing fabric 29. The characteristics of the noise absorbing fabric 29 are shown in Table 1.

[Examples 30 and 31]
In Examples 30 and 31, the noise absorbing fabrics 30 and 31 were respectively changed in the same manner as in Example 29 except that the extrusion amount of polyethylene terephthalate was changed and the fiber diameters of the nonwoven fabric layer A and the nonwoven fabric layer B were changed. Formed. The characteristics of the noise absorbing fabrics 30 and 31 are shown in Table 1.

[Examples 32-34]
In the same manner as in Example 29, after forming a two-layer laminated web of the web layer A and the web layer B, the two-layer laminated web was thermocompression-bonded between two flat rolls, and the web layer A A two-layer laminated nonwoven fabric having a nonwoven fabric layer A derived from the web and a nonwoven fabric layer B derived from the web layer B, and a polyaniline on the nonwoven fabric layer B and a screen printing method using a 200 mesh screen And the fabric was dried at 80 ° C. for 10 minutes to form noise absorbing fabrics 32-34. The characteristics of the noise absorbing fabrics 32-34 are shown in Table 1.

[Examples 35 to 37]
In Example 29, after forming a single layer web only of the web layer B without forming the web layer A, the single layer web was thermocompression-bonded between two flat rolls to form a single layer nonwoven fabric. Obtained. Further, a single-layer nonwoven fabric in which the fiber diameter was changed by changing the extrusion amount was prepared, and polyaniline was adhered on each single-layer nonwoven fabric by a screen printing method using a 200-mesh screen. It was made to dry at 80 degreeC for 10 minute (s), and the noise absorption fabric 35-37 was formed. The characteristics of the noise absorbing fabrics 35 to 37 are shown in Table 1.

[Examples 38 and 39]
In Example 29, after forming the single layer web of only the web layer A without forming the web layer B, the single layer web was thermocompression-bonded between two flat rolls to obtain a single layer nonwoven fabric. It was. Further, a single-layer nonwoven fabric in which the fiber diameter was changed by changing the extrusion amount was prepared, and polyaniline was adhered on each single-layer nonwoven fabric by a screen printing method using a 200-mesh screen. The properties of the noise absorbing fabrics 38 and 39 are shown in Table 1 after being dried at 80 ° C. for 10 minutes.

[Examples 40 to 43]
A non-woven fabric made of ultrafine fibers formed by the electrospinning method (ELSP) manufactured by Finetex Technology Global Limited was superposed on Presise AS030 (material: PET, manufactured by Asahi Kasei Fiber) to form a laminated non-woven fabric. Then, polyaniline was adhered to the side of the nonwoven fabric made of ultrafine fibers by a screen printing method using a 200 mesh screen, and the fabric was dried at 80 ° C. for 10 minutes to form noise absorbing fabrics 40 to 43. The characteristics of the noise absorbing fabrics 40 to 43 are shown in Table 1.
The processing amount of ELSP was 2 g / m ² or 1 g / m ² . The ultrafine fiber material was nylon 6 in Examples 40 and 41 and PVDF in Examples 42 and 43.

[Example 44]
A noise absorbing fabric 44 was formed according to the method described in Example 21, except that the conductive polymer was changed to Shin-Etsu polymer PEDOT (Serupzieta). The characteristics of the noise absorbing fabric 44 are shown in Table 1.
[Example 45]
A noise absorbing fabric 45 was formed according to the method described in Example 44, except that the fabric was changed to Presise AS030. The characteristics of the noise absorbing fabric 44 are shown in Table 1.

[Example 46]
The method of attaching the conductive polymer was changed from the gravure printing method to the Dip-Nip method, and the drying method was changed to 75 ° C. for 7 minutes. Formed. The characteristics of the noise absorbing fabric 46 are shown in Table 1.
[Example 47]
A noise absorbing fabric 47 was formed according to the method described in Example 46, except that the fabric was changed to Precise AS030. The characteristics of the noise absorbing fabric 47 are shown in Table 1.

[Comparative Example 1]
A comparative sheet 1 was formed in accordance with Example 1 except that the gravure plate was changed and the coating amount of the conductive polymer was changed. Table 2 shows the characteristics of the comparative sheet 1. Moreover, the measurement result by the microstrip line method of the comparative sheet 1 is shown in FIG.
[Comparative Examples 2 to 4]
Comparative sheets 2 to 4 were formed according to Example 22 except that the number of times of printing by the screen printing method was changed. Table 2 shows the characteristics of the comparative sheets 2 to 4.

[Comparative Examples 5 to 7]
In Comparative Examples 5 to 7, Comparative Sheets 5 to 7 were formed in accordance with the methods described in Examples 1, 22 and 46, respectively, except that the fabric was changed to a PET film. Table 2 shows the characteristics of the comparative sheets 5 to 7.
The PET film is a Teijin Tetron film (model G2: 16 μm, model S: 188 μm).

[Comparative Example 8]
A comparative sheet 8 was formed according to Example 22 except that the PET film was changed to a polyimide film (Toray DuPont, model H type: 25 μm). The characteristics of the comparative sheet 8 are shown in Table 2.
[Comparative Example 9]
A commercially available product (Busterade type R4N) was used as the comparative sheet 9. Table 2 shows the characteristics of the comparative sheet 9.

[Comparative Example 10]
In accordance with Japanese Patent Application Laid-Open No. 2010-80911, the following radio wave absorber was produced. 12% by mass of ammonium persulfate on a wiper WO-ME150 non-woven fabric (basis weight: 150 g / m ² , thickness: 0.45 mm, polyester ultrafine fiber 100%, width: 50 cm, and length: 300 cm) manufactured by Mitsubishi Paper Industries, Ltd. Then, it was immersed in an aqueous solution (pH 0.2) of 14% by mass of naphthalenesulfonic acid, and excess solution was removed with a mangle.

  Thereafter, the soaked WO-ME150 non-woven fabric was put in a reaction chamber in a state of being flattened, filled with pyrrole vapor from an evaporator installed in a draft, and allowed to stand for 10 minutes for vapor phase polymerization of pyrrole. . After completion of the reaction, the WO-ME150 non-woven fabric obtained by vapor-phase polymerization of pyrrole was taken out of the reaction chamber, washed with 10 L of distilled water three times, drained with mangles, and dried at 105 ° C. for 1 hour. The obtained nonwoven fabric was cut into a size of 30 × 30 cm, and 10 obtained nonwoven fabrics were bonded together with a double-sided adhesive tape (No. 5000NS) manufactured by Nitto Denko Corporation to form a comparative sheet 10. Table 2 shows the characteristics of the comparative sheet 10.

DESCRIPTION OF SYMBOLS 1 Noise absorption fabric 2 Fabric 3 Conductive polymer 4 Fiber 5 Conductive polymer cluster 5 'Electrical contact of each cluster 6 Microstrip line fixture 7 Sample 8 Network analyzer 9 Microstrip line

Claims (12)

A noise absorbing fabric in which a conductive polymer is attached to the fabric fibers,
The common logarithm of the surface resistivity of at least one surface of the noise absorbing fabric is in the range of 0 to 4,
The noise absorbing fabric.   The noise-absorbing fabric according to claim 1, wherein the fabric is formed by coating a conductive polymer solution on the fabric, or coating the fabric with a conductive polymer precursor and polymerizing the precursor.   The noise-absorbing fabric according to claim 1 or 2, wherein the fabric is a nonwoven fabric made of synthetic long fibers.   The noise-absorbing fabric according to any one of claims 1 to 3, wherein the fabric includes fibers having a fiber diameter of 7.0 µm or less.   The fabric is a laminated fabric having at least two layers of a first layer and a second layer, the first layer is a non-woven fabric layer made of fibers having a fiber diameter of 10 to 50 μm, and the second layer The noise-absorbing fabric according to any one of claims 1 to 4, wherein the layer is a non-woven fabric layer made of fibers having a fiber diameter of 0.01 to 7.0 µm.   The cloth is a laminated cloth having at least three layers of a first layer, a second layer, and a third layer in that order, and the first layer and the third layer have a fiber diameter of 10 to 50 μm. The noise according to any one of claims 1 to 5, wherein the second layer is a nonwoven fabric layer made of fibers having a fiber diameter of 0.01 to 7.0 µm. Absorbent fabric.   5. The fabric according to claim 1, wherein the fabric is a fabric in which fibers having a fiber diameter of 10 to 50 μm and fibers having a fiber diameter of 0.01 to 7.0 μm are mixed. Noise absorbing fabric. The noise-absorbing fabric according to any one of claims 1 to 7, wherein the fabric has a thickness of 10 to 200 µm and a basis weight of 7 to 150 g / m ² .   The noise absorbing fabric according to any one of claims 1 to 8, which is calendered.   The noise-absorbing fabric according to any one of claims 1 to 9, wherein a reflection attenuation amount (S11) at 1 GHz is 0.2 or less.   The noise-absorbing fabric according to any one of claims 1 to 10, wherein an average pore diameter is 0.5 µm to 5.0 mm.   The noise-absorbing fabric according to any one of claims 1 to 11, wherein the conductive polymer is selected from the group consisting of an aniline polymer, a thiophene polymer, and a pyrrole polymer.

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