JP5785321B2 - Conductive fiber structure, metal porous structure, battery electrode material, and battery - Google Patents

Description

  The present invention provides a conductive fiber structure in which a metal film is formed on a fiber surface, a metal porous structure obtained by firing the conductive fiber structure, and the conductive fiber structure or metal porous structure. It is related with the battery electrode material used, and the battery using those battery electrode materials.

  Various porous structures have been proposed as conductive porous structures used in various electronic parts such as battery materials such as electrode materials, electromagnetic wave sealing materials, filters, accessories, and grounding materials. Yes.

  As a conductive porous structure, for example, a sponge-like material made of resin such as urethane foam is subjected to a treatment such as plating, vacuum deposition, or chemical vapor deposition, and the surface thereof is nickel, copper, chromium, cobalt, or the like. A conductive porous structure having a metal film formed thereon is known. Furthermore, the porous structure which consists of a metallic fibrous material obtained by baking the electroconductive porous structure which formed the metal membrane | film | coat, and lose | disappearing urethane foam (henceforth "metal porous structure") Is also known as a conductive porous structure. A conductive porous structure in which a metal film is formed on a sponge-like material is uniform in the thickness direction, length direction, and width direction of the sheet, and is therefore suitable for use as a conductor. However, a conductive porous structure using foamed urethane and a metal porous structure obtained by firing foamed urethane have the disadvantages of low sheet strength and poor workability.

  Further, when producing a conductive porous structure and a metal porous structure using urethane foam, it is necessary to cut (slice) the urethane foam to a thickness suitable for the practical use. When the foamed urethane is cut, as shown in FIG. 10, a large number of end portions where the skeleton portion is cut are formed, and a part thereof is a needle-like shape that stands upright in the direction perpendicular to the cut surface as shown in FIG. Protrusions may be formed. For example, the needle-like projections cause dendrite to be formed when a conductive porous structure or a metal porous material is incorporated into a battery as an electrode material. When this dendrite grows, it may penetrate and / or break the separator inside the battery, causing a short circuit.

  Therefore, a fiber structure using a polyolefin fiber, an acrylic fiber, or a carbon fiber instead of urethane foam as a material for forming a conductive porous structure or the like has been proposed. Specifically, a conductive fiber structure (hereinafter also referred to as “conductive fiber structure”), a conductive fiber structure in which a metal film is formed on a fiber structure such as a nonwoven fabric produced using the fiber, and a conductive fiber structure A porous metal structure in which a nonwoven fabric is eliminated by baking and a battery electrode material using them has been proposed. For example, Patent Document 1, Patent Document 2, and Patent Document 3 disclose a conductive fiber structure using a nonwoven fabric using synthetic fibers, a metal porous structure, and a battery electrode material using them. is there. Patent Document 4 is cited as a document disclosing conductive fiber structures and metal porous structures using acrylic fibers, and documents disclosing conductive fiber structures and metal porous structures using carbon fibers. There exists patent document 5.

JP 2006-310261 A JP 2008-66145 A JP 2009-293156 A JP 2005-82895 A JP-A-8-60508

  The conductive fiber structure and the metal porous structure are required to have higher electrical conductivity. Electrical conductivity is affected by various factors. For example, higher electrical conductivity is due to the presence of a conductive metal film having a higher continuity in a conductive fiber structure or a metal porous structure (ie, fewer discontinuities in the conductor). Secured. The continuity of the conductor is affected by the structure of the fiber structure on which the metal film is formed.

  In addition, the conductive fiber structure, the metal porous structure, and the battery electrode material using the same disclosed in the above-mentioned patent documents all use a nonwoven fabric of fibers (including carbon fibers) made of an organic material. Yes. Therefore, they are flexible, and when used as a battery electrode material, their performance does not deteriorate even if they are wound. Therefore, they are excellent in processability as compared with conductive porous structures and metal porous structures using urethane foam, but have the following drawbacks. First, in the conductive fiber structure using carbon fiber disclosed in Patent Document 5, since the carbon fiber used as a raw material does not have thermal adhesiveness, a resin serving as a binder is required when producing the fiber structure. is necessary.

Next, the conductive fiber structure disclosed in Patent Document 4 uses an acrylic fiber and a nonwoven fabric obtained by a hydroentanglement method. This nonwoven fabric is a nonwoven fabric having a high apparent density of 0.2 g / cm ³ or more and few voids between fibers. The conductive fiber structure produced using a non-woven fabric with a high apparent density has a lower air permeability or is easier to handle than a conductive porous structure in which a metal film is formed on a sheet using urethane foam. It is bad and has the subject that post-processability falls. Moreover, when using for the use which fills the inside of the said conductive fiber structure or the said metal porous structure, since the space | gap between fibers is few, the filling property of a filler worsens.

  Moreover, since the nonwoven fabric using the core-sheath-type composite fiber which consists of polyolefin resin currently disclosed by patent documents 1-3 has a small difference between melting | fusing point of the sheath component of the said core-sheath-type composite fiber, and melting | fusing point of a core component. The heat treatment may cause so-called “sagging” in which the bulk of the nonwoven fabric decreases. In the conductive fiber structure, when the constituent fibers are not bonded to each other, various electrical characteristics are deteriorated. Therefore, the constituent fibers are required to be firmly bonded to each other. Therefore, it is required that the temperature of the heat treatment for bonding the fibers is higher. However, as the heat treatment is performed at a higher temperature, the “sagging” of the nonwoven fabric becomes more prominent. Due to the “sagging” of the nonwoven fabric, the bulk of the nonwoven fabric and the inter-fiber gap are reduced, and the nonwoven fabric becomes dense. Therefore, the problem described in relation to Patent Document 4 occurs.

  Moreover, the conductive fiber structure, metal porous structure, and battery electrode material using them described in Patent Documents 1 to 4 are manufactured from a nonwoven fabric using a fiber web, for example, a card web. In a nonwoven fabric produced using a fiber web, particularly a card web, the constituent fibers tend to be oriented in one direction, particularly in the MD direction of the nonwoven fabric (hereinafter also referred to as the longitudinal direction or production direction). Therefore, in the obtained conductive fiber structure, metal porous structure, and battery electrode material using them, the mechanical properties, such as tensile strength, are high in the MD direction of the nonwoven fabric, and the CD direction (hereinafter referred to as the transverse direction). Tend to be low in the direction or width direction). Furthermore, the electrical conductivity of the obtained conductive fiber structure and metal porous structure tends to be high in the MD direction and low in the CD direction.

  The present invention has a conductive fiber structure and a metal porous structure having good electrical characteristics, preferably bulky, and preferably low in direction dependency in mechanical characteristics and electrical conductivity characteristics, and using the same It aims at providing the electrode material for batteries, and the various batteries incorporating them.

  The present inventor has studied to solve the above-mentioned problems, and performs a treatment for imparting electrical conductivity such as plating to a laminate formed by laminating a predetermined long fiber sheet-like material on a short fiber layer. The present inventors have found that a conductive fiber structure that solves the above problems can be obtained.

The present invention is a conductive fiber structure in which a metal film is formed on the fiber surface of the fiber structure,
The fiber structure includes at least one short fiber layer and at least one long fiber sheet.
The long fiber sheet-like material includes long fibers continuously extending in one direction of the sheet, and long fibers continuously extending in a direction crossing the one direction,
In the fiber structure, the fibers constituting the short fiber layer, and the fibers constituting the short fiber layer and the long fibers constituting the long fiber sheet are entangled.
A conductive fiber structure is provided.

The present invention also provides a metal porous structure composed of metal fibers. The metal porous structure of the present invention is a metal porous structure composed of at least one metal fiber selected from hollow metal fibers having a thickness of 1 μm or more and metal fibers having a short side of 2 μm or more in the fiber cross section. A thing,
As metal fibers constituting the metal porous structure, there are short metal fibers and long metal fibers having different fiber lengths,
The metal porous structure includes at least one short metal fiber layer including the short metal fiber, and at least one long metal fiber layer including the long metal fiber,
The long metal fiber layer includes a long metal fiber continuously extending in one direction of the sheet, and a long metal fiber continuously extending in a direction intersecting the one direction,
At least a part of the short metal fiber is a porous metal structure characterized in that the short metal fiber is bonded to the long metal fiber at an intersection with the long metal fiber.

  In the metal porous structure of the present invention, preferably, the heat-dissipative substance is heated by subjecting the conductive fiber structure, in which the short fiber layer and the long fiber sheet are made of a heat-dissipative substance, to a heat treatment. It is removed.

  The present invention also provides a battery electrode material in which the conductive fiber structure or the metal porous structure is filled with an active material mixture.

  The present invention also provides various batteries using the battery electrode material as an electrode material, preferably a positive electrode material.

  The conductive fiber structure, metal porous structure, and battery electrode material of the present invention include a specific long fiber sheet-like material and a short fiber layer, and have a fiber structure in which constituent fibers are entangled with each other. Or manufactured using this fiber structure. With this feature, the conductive fiber structure, metal porous structure, and battery electrode material of the present invention have good electrical conductivity. Further, by using a long fiber sheet-like material, it is possible to obtain a conductive fiber structure, a metal porous structure, and a battery electrode material using them, which are low in direction dependency in mechanical characteristics and electrical conduction characteristics. In particular, when an electrode material is produced using the conductive fiber structure of the present invention as a starting material, not only the direction dependency of the mechanical and electrical conduction characteristics of the conductive fiber structure is low, but also indispensable for the electrode material. Therefore, it is possible to stably produce a high-quality electrode material.

1 is a scanning electron microscope (SEM) photograph (magnification 50) showing the surface of the conductive fiber structure obtained in Example 2. FIG. FIG. 2 is a scanning electron microscope (SEM) photograph (magnification 300) showing a portion where the heat-adhesive conjugate fiber and the long fiber are thermally bonded on the surface of the conductive fiber structure obtained in Example 2. . FIG. 3 is a scanning electron microscope (SEM) photograph (magnification 300) showing a portion where the heat-adhesive conjugate fiber and the long fiber are thermally bonded on the surface of the conductive fiber structure obtained in Example 7. . FIG. 4 is a scanning electron microscope (SEM) photograph (magnification 50) showing the surface of the conductive fiber structure obtained in Comparative Example 2. FIG. 5 shows a portion where long metal fibers and short metal fibers are present on the surface of the metal porous structure obtained by removing the active material from the battery electrode material produced from the conductive fiber structure obtained in Example 7. It is the scanning electron microscope (SEM) photograph (magnification 100) shown. FIG. 6 shows a portion where long metal fibers and fine metal fibers are joined on the surface of the metal porous structure obtained by removing the active material from the battery electrode material produced from the conductive fiber structure obtained in Example 7. It is a scanning electron microscope (SEM) photograph (magnification 300) which shows. FIG. 7 shows a portion where long metal fibers and short metal fibers are present in the cross section of the metal porous structure obtained by removing the active material from the battery electrode material produced from the conductive fiber structure obtained in Example 7. It is a scanning electron microscope (SEM) photograph (magnification 100) which shows. FIG. 8 is a scanning electron microscope (FIG. 8) showing a magnified view of long metal fibers in a cross section of a metal porous structure obtained by removing the active material from the battery electrode material produced from the conductive fiber structure obtained in Example 7. SEM) photograph (magnification 400). FIG. 9 is a scanning electron microscope (SEM) photograph (magnification 100) showing a cross section of a metal porous structure obtained by removing the active material from the battery electrode material produced from the conductive fiber structure obtained in Comparative Example 2. is there. FIG. 10 is a scanning electron microscope (SEM) photograph (magnification 100) showing the surface after removing the active material from the electrode material using a metal porous structure in which a metal film is formed on foamed urethane. FIG. 11 is a scanning electron microscope (SEM) photograph (magnification 100) showing a cross section after removing the active material from the electrode material using a metal porous structure in which a metal film is formed on foamed urethane.

  The conductive fiber structure of the present invention is a conductive fiber structure in which a metal film is formed on the fiber surface of the fiber structure, and the fiber structure includes at least one short fiber layer and at least one short fiber layer. Including a long fiber sheet, the long fiber sheet has long fibers continuously extending in one direction of the sheet, and long fibers continuously extending in a direction intersecting the one direction, and the fiber structure In the product, the fibers constituting the short fiber layer, the fibers constituting the short fiber layer, and the long fibers constituting the long fiber sheet are entangled. In this specification, a fiber structure refers to a structure in which a metal film is not formed, and a conductive fiber structure refers to a structure in which a metal film is formed. In this conductive fiber structure, since the fibers of the short fiber layer are entangled well due to the presence of the long fiber sheet, the metal film forms a network having good continuity, and has excellent electrical properties. Shows conductivity.

  In addition, the long fiber sheet-like material is not large in the proportion of the constituent fibers oriented in a specific direction, for example, the MD direction, compared to the short fiber layer, and in a direction intersecting the specific direction, for example, the CD direction. Also the fibers are oriented. Thereby, in the conductive fiber structure, high conductivity is given not only in the specific one direction but also in a direction intersecting with the one direction. As a result, for example, the difference between the electrical resistance in the MD direction and the electrical resistance in the CD direction can be reduced. Further, the long fiber sheet-like material can give good mechanical properties not only in one specific direction but also in a direction intersecting the one direction in the conductive fiber structure, for example, in the MD direction. The difference between the strength and the tensile strength in the CD direction can be reduced.

Below, the long fiber sheet-like material which comprises the electroconductive fiber structure of this invention is demonstrated. The long fiber sheet-like material constituting the conductive fiber structure of the present invention has long fibers continuously extending in one direction of the sheet and long fibers continuously extending in a direction intersecting with the specific one direction. “Long fiber” refers to a fiber that continuously extends in a predetermined direction in a sheet-like material having a predetermined size when a sheet-like material including the same is used in a predetermined size. The long fiber contained in the long fiber sheet has a sufficient length as long as it has a fiber length of 150 mm or more, but is preferably continuous in the sheet having the predetermined size. That is, it is continuous between both ends in one direction of the sheet. The long fiber is a yarn (for example, spun yarn), a multifilament, a monofilament, or the like in which short fibers are aggregated and continuously extend. Examples of the long fiber sheet-like material include sheet-like materials such as a warp stretched nonwoven fabric, a woven fabric, a knitted fabric, a net-like sheet, and a mesh-like sheet. The thickness of the long fiber sheet is preferably 5 mm or less when measured with a 2.94 cN / cm ² load. A more preferable thickness is 0.03 mm or more and 3 mm or less, and a particularly preferable thickness is 0.05 mm or more and 1 mm or less. When the thickness of the sheet-like material is 5 mm or less, the productivity of the conductive fiber structure can be increased, and the obtained conductive fiber structure is easy to handle.

  As the long fiber sheet, it is preferable to use a net-like sheet (hereinafter also simply referred to as “net-like”). The net-like material refers to a sheet having an opening surrounded by continuous fibers extending continuously in at least two different directions. When the net-like material is used as a long fiber sheet material, the fibers of the short fiber layer are entangled better, the continuity of the metal film is improved, and excellent electrical conductivity is obtained.

  The net-like object will be described. In a net-like material, long fibers regarded as continuous fibers are continuous in one direction and in a direction crossing the one direction in a sheet-like material of that size when cut into a predetermined size at the time of use. Contains fiber. The net-like object is formed by arranging continuous fibers that are oriented in at least two different directions and extend continuously. The continuous fibers may be arranged to be oriented in two different directions, may be arranged to be oriented in three or more different directions, or may be arranged in a completely random state. The net-like material is preferably formed by aligning continuous fibers in four or less different directions, and particularly preferably formed by aligning continuous fibers in two different directions.

  In the net-like object, an opening surrounded by continuous fibers aligned in two or more different directions is formed. When the continuous fibers are arranged in a completely random state, the shape of the opening also becomes a random shape accordingly. As described above, the continuous fibers are preferably aligned in four or less directions, and particularly preferably aligned in two directions. Therefore, the shape of the opening is preferably a triangle, square, rectangle, or rhombus, and is particularly preferably a square, rectangle, or rhombus.

  In the net-like material, the direction in which the continuous fibers continuously extending in one specific direction constituting the sheet is oriented may be any direction. Further, in the net-like object, the continuous fiber extending in one specific direction and the continuous fiber extending continuously in the direction intersecting with the one direction may be joined at any angle or at a crossing point. Good. The continuous fibers extending continuously in two different directions preferably form an acute angle of 30 ° or more and 90 ° or less, more preferably 45 ° or more and 90 ° or less, and particularly preferably 60 ° or more and 90 ° or less. Or join at the crossing point. A net that forms such an acute angle and the continuous fibers are oriented in two directions makes the electrical and / or mechanical properties of the conductive fiber structure less dependent on direction.

  The net-like material is a net-like material in which continuous fibers are aligned in two different directions and a continuous fiber that is continuous in one specific direction and a continuous fiber that intersects the continuous fiber are orthogonal to each other (hereinafter referred to as “orthogonal net”). It is also preferable to be referred to as a “form”. This is because the orthogonal net-like material is easily available and has a high effect of reducing the direction dependency of the electrical properties and / or mechanical properties of the conductive fiber structure.

  In the net-like material, the interval between the continuous fibers constituting the net-like material (hereinafter simply referred to as “mesh”) is not particularly limited, and is preferably 1 mm or more and 20 mm or less, for example. If the mesh size is less than 1 mm, the air permeability of the conductive fiber structure is lowered, and there is a possibility that it is not suitable for applications requiring air permeability. If the mesh is too narrow, depending on the fiber diameter of the continuous fibers constituting the net-like material, it may become hard or difficult to bend. Handling of the net-like material and the conductive fiber structure including the net-like material may be difficult. And post-processability may be deteriorated. Furthermore, when the mesh is too narrow, when the short fiber layer and the net-like material to be described later are entangled, particularly when the net-like material is sandwiched between the two short fiber layers and entangled and integrated, the fibers of the short fiber layer There is a tendency that the entanglement between the fibers and the continuous fibers constituting the net-like object, or the entanglement between the fibers of the two short fiber layers located on both sides of the net-like object is reduced. A decrease in confounding may cause a decrease in electrical conductivity in the obtained conductive structure.

  On the other hand, if the mesh size exceeds 20 mm, not only the effect of reducing the direction dependency of the mechanical and / or electrical conductive properties of the conductive fiber structure may be lowered, but also the handling property of the net-like material itself. May deteriorate and the productivity of the conductive fiber structure may decrease. The mesh size of the net-like material is more preferably 1 mm or more and 15 mm or less, particularly preferably 2 mm or more and 10 mm or less, and most preferably 3 mm or more and 9 mm or less. The mesh formed by continuous fibers extending in one direction (for example, the MD direction) and the mesh formed by continuous fibers extending in the direction intersecting the one direction (for example, the CD direction) both within the above range. It is preferable to satisfy. In addition, continuous fibers may be arranged so that each mesh is within the above range, and different meshes are randomly generated (irregularly). Is preferably arranged so as to be a repetition of 3 mm and 5 mm, and particularly preferably arranged so as to have a uniform scale of a specific value. Further, the mesh formed by the continuous fibers in one direction and the mesh formed by the continuous fibers in the direction intersecting the one direction may be different, but it is particularly preferable that both have the same value.

In the long fiber sheet-like material, the area of the opening formed by the long fibers continuously extending in at least two directions (hereinafter simply referred to as “opening area”) is not particularly limited, but is 1 mm ² or more and 500 mm ^2. The following is preferable. When the opening area is less than 1 mm ² , the air permeability of the conductive fiber structure is lowered, and there is a possibility that it is not suitable for an application requiring air permeability. In addition, if the opening area is too small, depending on the fiber diameter of the long fibers constituting the long fiber sheet-like material, it may become hard or difficult to bend. The handleability and post-processability of the porous fiber structure may be reduced. Furthermore, if the opening area is too small, when the short fiber layer and the long fiber sheet material to be described later are entangled, especially when the long fiber sheet material is sandwiched between the two short fiber layers, The confounding property between the fibers of the short fiber layer and the long fibers constituting the long fiber sheet material, or the confounding property between the fibers of the two short fiber layers located on both sides of the long fiber sheet material tends to decrease. A decrease in confounding may cause a decrease in electrical conductivity in the obtained conductive structure.

On the other hand, if the opening area exceeds 500 mm ² , not only the effect of reducing the direction dependency of the mechanical and / or electrical conduction characteristics of the conductive fiber structure may be deteriorated, but also the long fiber sheet-like material. The handleability itself may deteriorate, and the productivity of the conductive fiber structure may decrease. The opening area of the long fiber sheet is more preferably 4 mm ² or more and 250 mm ² or less, particularly preferably 9 mm ² or more and 100 mm ² or less, and most preferably 12 mm ² or more and 80 mm ² or less. preferable.

  The fiber diameter of the long fibers constituting the long fiber sheet (including the mesh nonwoven fabric, the weft stretched nonwoven fabric, and the net-like material) is not particularly limited, but is preferably 0.5 μm or more and 1000 μm or less. When the fiber diameter of the long fiber is 0.5 μm or more, in the long fiber sheet-like material, it is avoided that the fiber density becomes too dense and the inter-fiber voids become too small, which is good with the fibers of the short fiber layer. Entangled in. Further, when the fiber diameter of the long fiber is 0.5 μm or more, a long fiber sheet-like product having excellent electrical characteristics can be obtained by forming a metal film on the long fiber surface. When the fiber diameter of the long fibers is 1000 μm or less, it is avoided that the long fiber sheet is too hard or difficult to bend. Therefore, in the process of laminating the short fiber layer on the long fiber sheet during the production of the conductive fiber structure, the productivity does not decrease and the handleability of the conductive fiber structure does not decrease.

  When the long fiber sheet is a net-like material having an opening surrounded by continuous fibers extending continuously in at least two different directions, the fiber diameter of the continuous fibers is more preferably 30 μm or more and 500 μm or less. Preferably, it is 50 μm or more and 300 μm or less, and most preferably 80 μm or more and 250 μm or less. The continuous fibers constituting the net-like material may be yarns (for example, spun yarn), multifilaments, monofilaments, etc., in which short fibers are gathered and continuously extended, preferably monofilaments or multifilaments. Particularly preferred are monofilaments. When the long fiber sheet is a non-woven fabric, the fiber diameter of the long fibers is preferably 1 μm or more and 100 μm or less, more preferably 3 μm or more and 50 μm or less, and more preferably 5 μm or more and 30 μm or less. Particularly preferred.

  When the long fiber sheet is a net having an opening surrounded by continuous fibers extending continuously in at least two different directions, the method for producing the net is not particularly limited. The net-like product is preferably an extruded net obtained by extruding a molten thermoplastic resin. The extruded net can be used in an unstretched state, that is, in a state where it is not stretched in any direction such as the longitudinal direction and the transverse direction. A net obtained by stretching an unstretched extruded net in at least one direction of the vertical direction and the horizontal direction is more preferable. It is particularly preferable to use a longitudinal and transverse stretched net obtained by stretching an extruded net in both the longitudinal direction and the transverse direction. Since the longitudinal and transverse stretched nets are stretched in both the longitudinal direction and the transverse direction, the tensile strength is high in any direction and the handleability is excellent. Therefore, the strength of the conductive fiber structure can be increased by using the longitudinal and lateral stretched nets. In addition, a net obtained by stretching an unstretched extruded net in at least one direction in the longitudinal direction and the transverse direction is not only bonded at the intersection of continuous fibers continuous in different directions, but also at the intersection at the time of manufacture. By extending the thermoplastic resin in the vicinity of the intersection, the shape of the intersection expands in the plane direction. When a net having such a shape at the intersection is used for the conductive fiber assembly of the present invention, when the conductivity is given by sputtering or electrolytic plating, the vicinity of the intersection spreads (of the stretched resin) The portion also has conductivity, and the area of the portion having conductivity is increased. As a result, the electrical resistance of the conductive fiber assembly of the present invention and various electrode materials using the same is reduced, and the current collecting property is also improved.

  When the long fiber sheet-like material is a net-like material stretched in at least one direction, a portion where the long fibers constituting the net-like material intersect and are joined (hereinafter simply referred to as an intersection) is raised from the periphery. However, there is a case where a protruding portion having a height is formed. When using the said net-like thing in this invention, it is preferable to use the net-like thing which the intersection of long fibers protrudes and forms the projection part. By using such a net-like material, the net-like material is easily locked to the short fiber layer by the raised protrusions, and not only the productivity is improved, but also the net-like material and the short fiber layer are peeled off. It becomes difficult. Further, the intersection of the long fibers is raised and formed in a protrusion shape, so that the long fiber portion and the opening portion are thinner than the intersection portion and have a shape recessed from the intersection. Thereby, when the fiber web and the net-like object are entangled, the short fibers constituting the short fiber layer are entangled by avoiding the intersection part where the protrusion is formed, so that the fiber web is formed at a part other than the intersection point, for example, the opening part. Therefore, the entire nonwoven fabric including the opening of the net becomes bulky. In addition, because the short fibers constituting the short fiber layer are entangled with the net by avoiding the intersection portion where the protrusions are formed, the short fibers constituting the short fiber layer are easily filled into the opening portion of the net-like material, The short fiber layer and the net-like material are more firmly integrated. In addition, since the short fibers are densely filled in the opening portions, a network of the conductive short fibers is also formed in the openings of the net-like object by imparting conductivity. As a result, a decrease in electrical characteristics at the opening is avoided, and conductive fiber structures with uniform electrical characteristics that can effectively collect current from the active material filled in this part and various types A battery electrode material is obtained.

  In the net-like object, whether or not the intersection part of the long fibers forms a protrusion protruding from the periphery is measured by comparing the fiber diameter of the long fiber and the thickness (height) of the intersection part. it can. In the net-like product, the ratio of the thickness of the intersection of long fibers to the fiber diameter of the long fibers is 1.1 or more, that is, (the thickness of the intersection of long fibers) / (fiber diameter of the long fibers). It is preferable that it is 1.1 or more. When the thickness of the intersection is 1.1 times or more of the fiber diameter of the long fiber, the above-described effect is obtained, and there is no unevenness in the conductive fiber structure suitable for various applications, and electrical characteristics. A laminated fiber structure capable of easily producing a uniform battery electrode material is obtained. The ratio between the thickness of the intersection of long fibers and the fiber diameter of the long fibers is more preferably 1.2 or more, and particularly preferably 1.3 or more. The upper limit of the ratio between the thickness of the intersection between the long fibers and the fiber diameter of the long fibers is not particularly limited. If the ratio is greater than 4, the protrusions are too high, that is, the intersections are too thick, which may cause poor formation of the laminated fiber structure. Moreover, when the ratio is larger than 4, when the conductive fiber structure or various electrode materials are manufactured using the laminated fiber structure, the protrusion may be exposed as a metal protrusion on the surface. The ratio between the thickness of the intersection of the long fibers and the fiber diameter of the long fibers is preferably 4 or less, more preferably 2.5 or less, particularly preferably 2 or less, and most preferably 1.8 or less. In addition, when the fiber diameter of the long fiber which comprises a net-like thing has a difference by long fiber (For example, when the fiber diameter differs in the long fiber of MD direction and the long fiber of CD direction), the one where fiber diameter is larger The ratio of the thickness of the intersection between the long fibers and the fiber diameter of the long fibers is determined using the fiber diameter.

  The material (raw material) for forming the long fiber sheet is not particularly limited. Long fiber sheet materials include, for example, cellulosic natural fibers such as cotton and kenaf fibers, animal-derived natural fibers such as silk and wool, viscose rayon, cupra, and solvent-spun cellulose fibers (for example, lentigryocell). (Registered Trademark) and Tencel (Registered Trademark)) may be formed of one or more fibers selected from recycled fibers, synthetic fibers, and carbon fibers. In the case of producing a metal porous structure made of metal fibers from the conductive fiber structure of the present invention, the fibers constituting the long fiber sheet material need to be made of a heat-dissipating substance. “Heat-dissipating substance” is a substance having the property of decomposing or burning and disappearing when heated at a high temperature (however, the metal constituting the metal film does not deform).

When the long fiber sheet is made of a synthetic fiber, the synthetic fiber is not particularly limited as long as the synthetic fiber is a fiber made of a thermoplastic resin. Specifically, as a thermoplastic resin,
Polyethylene (including high density, low density, linear low density polyethylene), polypropylene, polybutene, polybutylene, polymethylpentene, polybutadiene, ethylene copolymer (for example, ethylene-α olefin copolymer), propylene copolymer Polymers (eg, propylene-ethylene copolymers), ethylene-vinyl alcohol copolymers, ethylene-vinyl acetate copolymers, ethylene- (meth) acrylic acid copolymers, and ethylene-methyl (meth) acrylate copolymers Polyolefin resins such as polymers,
Polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid, polybutylene succinate and copolymers thereof,
Polyamide resins such as nylon 66, nylon 12 and nylon 6,
Acrylic resin,
Engineering plastics such as polycarbonate, polyacetal, polystyrene and cyclic polyolefin,
These mixtures, as well as their elastomeric resins. A single-component long fiber using one kind of the above-mentioned thermoplastic resin or a composite long fiber using two or more kinds of the above-mentioned thermoplastic resins can be used for the long-fiber sheet-like material. As will be described later, when the short fiber layer includes a heat-adhesive fiber, considering the heat adhesion with the heat-adhesive fiber, at least the surface of the long fiber constituting the long-fiber sheet-like material includes a polyolefin-based resin. It is preferably a long fiber composed of components.

  The cross-sectional shape of the long fiber may be any shape. Specifically, in addition to a long fiber having a circular (perfect circle) cross section, a long fiber having a non-circular cross-sectional shape, that is, a so-called irregular cross-section long fiber can be used. As an irregular cross section, a polygonal shape, an elliptical shape, a flat shape, a so-called multileaf shape (specifically, a multileaf shape of 3 to 32 leaves) having a number of branch portions on the fiber surface, Examples are a star shape, a C shape, a Y shape, a W shape, and a well shape. Further, the long fiber may be a solid fiber that does not have a hollow portion that is continuous in the length direction in the fiber cross section, or may be a hollow fiber that has one or more hollow portions that are continuous in the length direction. Good.

Basis weight of the long fiber sheet is not particularly limited, it is preferably 2 g / m ² or more and 100 g / m ² or less. When the basis weight of the long fiber sheet is 2 g / m ² or more, the conductive fiber structure of the present invention including the long fiber sheet is excellent in mechanical properties. When the basis weight of the long fiber sheet is 100 g / m ² or less, the conductive fiber structure of the present invention including the long fiber sheet has an appropriate thickness, and handling properties and post-processability are improved. Can be good. The basis weight of the long fiber sheet is more preferably 3 g / m ² or more and 70 g / m ² or less, particularly preferably 4 g / m ² or more and 50 g / m ² or less, and 5 g / m ² or more. 40 g / m ² or less is most preferable.

When the conductive fiber structure of the present invention is subjected to a heat treatment to form a metal porous structure, and this metal porous structure is filled with an active material mixture to produce a battery electrode material, the long fiber sheet is An orthogonal net-like material composed of continuous fibers having a fiber diameter of 70 μm or more and 300 μm or less, preferably monofilaments, having a mesh size of 2 mm or more and 10 mm or less in any direction, and an opening area of 4 mm ² or more. It is preferably an orthogonal net-like material of 100 mm ² or less. Such an orthogonal net-like material enables the constituent fibers of the short fiber layer and the constituent fibers of the short fiber layer and the monofilaments of the orthogonal sheet-like material to be entangled satisfactorily in the fiber structure.

  As a commercially available mesh nonwoven fabric, there is, for example, Warif (registered trademark) sold by JX Nippon Mining & Metals Anci Co., Ltd. There is Milife (registered trademark) sold by the company. These long fiber sheets are not only excellent in dimensional stability, but also have a wide variety, so that the optimum thickness and basis weight can be selected according to the characteristics required of the conductive fiber structure. .

  Examples of commercially available nets include, for example, Conwed (registered trademark) net sold by JX Nippon Mining & Metals Anci Corporation, and Delnet (registered trademark) sold by DelStar (DelStar Technologies, Inc.). and so on. Conwed (registered trademark) nets are preferred because they are abundant in types and can be selected to have the optimum thickness, basis weight, mesh size, and opening area according to the characteristics required of the conductive fiber structure.

  Next, the short fiber layer which comprises the electroconductive fiber structure of this invention is demonstrated. The short fiber layer refers to a fiber aggregate in which short fibers are opened and accumulated, and is a concept that includes a fiber bonded to each other. The type of fiber constituting the short fiber layer, the fiber diameter, the fineness, the cross-sectional shape of the fiber, and the fiber length are not particularly limited, and various fiber webs such as the basis weight, thickness, porosity, and air permeability of the short fiber layer The physical properties are not particularly limited.

  The short fiber layer is made of known fibers, for example, cellulose-based natural fibers such as cotton and kenaf fibers, animal-derived natural fibers such as silk and wool, viscose rayon, cupra, and solvent-spun cellulose fibers (for example, It may be formed of one or a plurality of fibers selected from regenerated fibers such as lentigo lyocell (registered trademark) and tencel (registered trademark), synthetic fibers, and carbon fibers. When producing a metal porous structure made of metal fibers from the conductive fiber structure of the present invention, it is necessary that the fibers constituting the short fiber sheet are made of a heat-dissipating substance.

When the short fiber layer is made of a synthetic fiber, the synthetic fiber is not particularly limited as long as it is a fiber made of a thermoplastic resin. Specifically, as a thermoplastic resin,
Polyethylene (including high density, low density, linear low density polyethylene), polypropylene, polybutene, polybutylene, polymethylpentene, polybutadiene, ethylene copolymer (for example, ethylene-α olefin copolymer), propylene copolymer Polymers (eg, propylene-ethylene copolymers), ethylene-vinyl alcohol copolymers, ethylene-vinyl acetate copolymers, ethylene- (meth) acrylic acid copolymers, and ethylene-methyl (meth) acrylate copolymers Polyolefin resins such as polymers,
Polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid, polybutylene succinate and copolymers thereof,
Polyamide resins such as nylon 66, nylon 12 and nylon 6,
Acrylic resin,
Engineering plastics such as polycarbonate, polyacetal, polystyrene and cyclic polyolefin,
These mixtures, as well as their elastomeric resins. A single fiber using one kind of the above thermoplastic resin or a composite fiber using two or more kinds of the above thermoplastic resins can be used for the short fiber layer.

  The short fiber may have any cross-sectional shape. Specifically, short fibers having a non-circular cross section, that is, short fibers having a so-called irregular cross section can be used in addition to short fibers having a circular (perfect circle) cross section. The irregular cross section includes a polygonal shape, an elliptical shape, a flat shape, a multi-leaf shape having a large number of branches on the fiber surface (specifically, a multi-leaf shape having 3 to 32 leaves), a star shape Examples include a shape, a C shape, a Y shape, a W shape, and a well shape. Further, the short fiber may be a solid fiber that does not have a hollow portion that is continuous in the length direction in the fiber cross section, or may be a hollow fiber that has one or more hollow portions that are continuous in the length direction. Good.

  The short fiber layer includes a heat-adhesive fiber, and the fibers constituting the short fiber layer are bonded to each other by the heat-adhesive fiber, and / or the fiber constituting the short fiber layer and the long fiber sheet are formed. It is preferable that the long fibers to be bonded are bonded. The intersection where the fibers are bonded to each other by the heat bonding fiber increases the strength of the entire conductive fiber structure. In addition, the metal film formed on the surface of the intersection is integrated, and the conductive fiber structure (and the metal porous structure obtained by removing the heat-dissipating substance therefrom) has good electrical conductivity. To ensure that. The thermoadhesive fiber may be a single fiber or a composite fiber composed of two or more resin components.

  In consideration of the workability during the heat bonding treatment, the heat bonding fiber preferably contains a low melting point synthetic resin exhibiting heat bonding properties at a low temperature in at least a part of the fiber surface. Specifically, the heat-adhesive fiber includes a low-melting synthetic resin and a high-melting synthetic resin having a melting point of 10 ° C. or more higher than the melting point of the low-melting synthetic resin (that is, the melting point (° C.) of the low-melting synthetic resin ≦ high The composite fiber is preferably a composite fiber in which the low-melting-point synthetic resin is exposed on at least a part of the fiber surface.

  As the composite form of the heat-adhesive conjugate fiber, the core-sheath type conjugate fiber (including the eccentric core-sheath type conjugate fiber in which the center of gravity of the high melting point core component is shifted from the center of gravity of the fiber), the parallel type conjugate fiber (“ Side-by-side type composite fiber), sea-island type composite fiber composed of a sea component composed of low-melting synthetic resin and island component composed of high-melting synthetic resin, and high-melting synthetic resin and low-melting synthetic resin in the fiber cross section Examples include split-type composite fibers arranged alternately (for example, split-type composite fibers in which citrus tufted resin components are alternately arranged in the fiber cross section). In this invention, the composite form of the heat bondable conjugate fiber used for a short fiber layer is not limited, The heat bondable conjugate fiber of any composite form can be used. In consideration of thermal adhesiveness between fibers, it is preferable to use a core-sheath type composite fiber.

  When the core-sheath type composite fiber is used as the heat-bonding fiber, the sheath component is composed of a low-melting synthetic resin as described above, and the core component is a high-melting-point synthetic material having a melting point of 10 ° C. or more higher than the melting point of the low-melting synthetic resin. Consists of resin. The combination of the low melting point synthetic resin of the sheath component and the high melting point synthetic resin of the core component is not particularly limited. Hereinafter, the sheath component and the core component of the thermoadhesive conjugate fiber will be described.

  As the sheath component of the core-sheath type composite fiber, polyolefin resin and low melting point synthetic resin such as copolymer polyester, polybutylene succinate, and polybutylene succinate adipate (also referred to as “polybutylene succinate agitate”) are used. can do. In the heat-bonding conjugate fiber used in the present invention, the sheath component is preferably made of a resin containing a polyolefin resin. Polyolefin resins include various polyolefin resins such as polyethylene, polypropylene, polybutene, polybutylene, polymethylpentene, and polybutadiene, ethylene copolymers such as ethylene-α olefin copolymers, and propylene-ethylene copolymers. , Propylene copolymers such as ethylene-propylene-butene terpolymer, ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meta ) Methyl acrylate copolymer and the like, as well as various copolymers composed of ethylene, propylene, or butene and other monomers. Examples of polyethylene include high density polyethylene, low density polyethylene, and linear low density polyethylene.

  When the sheath component of the heat-adhesive conjugate fiber is a polyolefin resin, a fiber structure excellent in chemical resistance such as acid resistance, alkali resistance, and organic solvent resistance can be obtained. In addition, since many of the polyolefin resins have a relatively low melting point, the constituent fibers are strongly heat-bonded by heat-processing the short fiber layer containing the heat-adhesive conjugate fiber of the polyolefin resin as the sheath component. Fibrous structures can be obtained at relatively low thermal processing temperatures. In the heat-adhesive conjugate fiber used in the present invention, the sheath component is polyethylene, ethylene copolymer, ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer. It is preferable that it contains at least one polyolefin resin selected from a coalescence and ethylene- (meth) acrylic acid methyl copolymer, more preferably the sheath component contains polyethylene, and particularly preferably the sheath component. Is made only of polyethylene.

  In the heat-adhesive conjugate fiber, the high melting point synthetic resin contained in the core component is 10 ° C. or higher than the melting point of the sheath component (when the sheath component is composed of a plurality of resins, the melting point of the resin having the highest melting point). If it is resin with high melting | fusing point, it will not specifically limit. When the core component is composed of two or more kinds of resins, the two or more kinds of resins are selected so that the melting point of the resin having the lowest melting point is higher by 10 ° C. or more than the melting point of the sheath component. Examples of the thermoplastic resin preferably used for the core component of the heat-adhesive conjugate fiber include relatively high melting point polyolefin resins such as polypropylene and polymethylpentene, polyethylene terephthalate, polybutylene terephthalate, and polytrimethylene terephthalate. Polyester resins such as nylon 66, nylon 12, and nylon 6 can be exemplified as the high melting point synthetic resin.

  As resin combinations (core / sheath) in the core-sheath type composite fiber (thermal adhesive composite fiber), polypropylene / high density polyethylene, polypropylene / low density polyethylene, polypropylene / linear low density polyethylene, polyethylene terephthalate / high density polyethylene Polyethylene terephthalate / low density polyethylene, polyethylene terephthalate / linear low density polyethylene, polyethylene terephthalate / copolyester, polypropylene / ethylene-propylene copolymer, polyethylene terephthalate / ethylene-propylene copolymer, polyamide / high density polyethylene, Polyamide / low density polyethylene, polyamide / linear low density polyethylene, polyamide / polypropylene, polylactic acid / polyethylene, polylactic acid / polybutylene Succinate, and combinations of the thermoplastic resin exemplified in polylactic acid / polybutylene succinate adipate.

  When the sheath component contains a polyolefin resin, the high melting point synthetic resin used for the core component is a thermoplastic resin having a melting point of 60 ° C. or higher than the melting point of the polyolefin resin contained in the sheath component, or a melting point of 180 ° C. or higher. The thermoplastic resin is preferably used. More preferably, the core component is made of a thermoplastic resin having a melting point higher by 80 ° C. or more than the melting point of the polyolefin resin, or a thermoplastic resin having a melting point of 200 ° C. or more. Examples of such high melting point synthetic resins include polyester resins and polyamide resins. The high melting point synthetic resin is preferably a polyester resin, more preferably at least one polyester resin selected from polyethylene terephthalate, polybutylene terephthalate, and polytrimethylene terephthalate, particularly preferably polyethylene terephthalate. is there.

  The core-sheath type composite fiber in which the core component includes a polyester-based resin and the sheath component includes a polyolefin-based resin is the temperature of the polyester-based resin that is the core component at a temperature at which the polyolefin-based resin is melted to bond the fibers together. Less likely to soften, deform or melt. Therefore, such a heat-adhesive conjugate fiber has high heat resistance as compared with a heat-adhesive conjugate fiber using a polyolefin resin as a core component, and even if a heat-bonding treatment described later is performed, the fiber structure This is advantageous in that the structure is well maintained. Further, such a heat-adhesive conjugate fiber can increase the bulk of the fiber structure. A heat-adhesive conjugate fiber in which the core component contains or consists of polyethylene terephthalate, and the sheath component contains or consists of polyethylene (one or more selected from high-density polyethylene, low-density polyethylene, and linear low-density polyethylene) Is particularly preferably used.

  In the heat-adhesive conjugate fiber preferably used for the short fiber layer, when heat resistance is important, the core component preferably contains a polyester resin as described above. However, the resin that constitutes the core component is not limited to the polyester-based resin, and it goes without saying that the resin that constitutes the core component may be selected from other synthetic resins depending on the performance that is important. For example, when the conductive fiber structure of the present invention or the fiber structure before forming the metal film is brought into contact with an alkaline solution or an organic solvent such as dimethylformamide and m-cresol, chemical resistance is required. In that case, the core component of the heat-adhesive conjugate fiber is preferably composed of polypropylene or polymethylpentene.

  In the heat-adhesive conjugate fiber, the composite ratio (core component / sheath component volume ratio) of the core component and the sheath component is not particularly limited. Considering the spinnability of the heat-adhesive conjugate fiber, easy heat adhesion during heat processing, durability against heat during heat processing, and the like, the composite ratio is preferably 2/8 or more and 8/2 or less. When the composite ratio is 2/8 or more, the fiber itself is stiff and can be a heat-adhesive fiber having excellent durability during heat processing. When the composite ratio is 8/2 or less, adhesion between fibers becomes strong when the constituent fibers are thermally bonded. The composite ratio of the heat-adhesive conjugate fiber is more preferably 2.5 / 7.5 or more and 7.5 / 2.5 or less, particularly preferably 3/7 or more and 7/3 or less, Most preferably, it is 3.5 / 6.5 or more and 6.5 / 3.5 or less.

  The fiber diameter of the heat-adhesive fibers (including single fibers and composite fibers) is not particularly limited, but is preferably 5 μm or more and 80 μm or less. When the fiber diameter of the heat-adhesive conjugate fiber is 5 μm or more, a gap between fibers is secured, and a short fiber layer that is less likely to be deformed and contracted by heat is obtained even when heat processing is performed, and a metal film is formed on the fiber surface. Sometimes, a fiber structure having excellent electrical characteristics can be obtained. When the fiber diameter of the heat-adhesive fiber is 80 μm or less, the productivity of the short fiber layer does not decrease, and the obtained short fiber layer is too hard. The handling property of the conductive fiber structure is not lowered. The fiber diameter of the heat-adhesive fiber contained in the short fiber layer is more preferably 8 μm or more and 50 μm or less, and particularly preferably 10 μm or more and 35 μm or less.

  The fiber length of the heat-adhesive fibers (including single fibers and composite fibers) is not particularly limited as long as the effect of the conductive fiber structure of the present invention and the productivity of the short fiber layer are not impaired. The fiber length of the heat-adhesive fiber is preferably 20 mm or more and 110 mm or less. When the fiber length of the heat-adhesive fiber is within this range, the productivity of the short fiber layer containing the heat-adhesive fiber is increased, and the effect of the conductive fiber structure of the present invention is not impaired. The fiber length of the heat-adhesive fiber is more preferably 25 mm or more and 85 mm or less, particularly preferably 30 mm or more and 80 mm or less, and most preferably 42 mm or more and 64 mm or less.

  The manufacturing method of the short fiber layer which comprises the electroconductive fiber structure of this invention is not specifically limited, It can obtain by a well-known method. For example, a parallel web, a semi-random web, a random web, a cross lay web, or a Chris cross web can be produced using a card machine, and this can be made into a short fiber layer. In this case, the fiber length of the heat-adhesive fiber is preferably 30 mm or more and 110 mm or less. The web produced using a card machine is particularly preferably used when the short fiber layer and the long fiber sheet are integrated by interlacing of fibers. Alternatively, the short fiber layer may be an air array web using an air array method, and in that case, the fiber length of the heat-adhesive fiber is preferably 20 mm or more and 30 mm or less.

  It is not necessary for the heat-bondable fibers contained in the short fiber layer to be only one type. Two or more types of thermal adhesiveness with different fiber cross-sectional shapes, composite forms of resin components, types of synthetic resin to be combined, fiber diameter, fiber length, core-sheath ratio, fineness, and / or manufacturing conditions for thermal adhesive fibers A combination of fibers may be used. For example, if at least one of the heat-adhesive fibers is a heat-adhesive conjugate fiber containing a hydrophilic resin in the sheath component, the formed metal film is fixed when the metal film is formed on the fiber structure. It becomes easy, and it becomes difficult for a metal membrane | film | coat to peel or drop | omit from a heat bondable composite fiber, and the electrical property of the conductive fiber structure of this invention can improve. Examples of the hydrophilic resin include ethylene-vinyl alcohol copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid alkyl copolymer, ethylene- (anhydrous) maleic acid copolymer, And a hydrophilic polyolefin-based resin such as an ethylene-acrylic acid-maleic anhydride copolymer.

  The ratio of the heat bondable fiber contained in the short fiber layer is not particularly limited. Preferably, 20 mass% or more of heat bondable fibers are contained with respect to the mass of the short fiber layer. When the short fiber layer contains 20% by mass or more of the heat-adhesive conjugate fiber, the constituent fibers of the short fiber layer and / or the fibers constituting the short fiber layer and the long fibers constituting the long fiber sheet are obtained. Can be well bonded. The proportion of the heat-bondable fibers contained in the short fiber layer is more preferably 50% by mass or more, particularly preferably 80% by mass or more, and 100% by mass with respect to the mass of the short fiber layer. Most preferred.

  The short fiber layer may contain fibers other than the heat-adhesive fibers or provide heat-adhesive properties as long as it provides desired electrical characteristics when a metal film is formed on the fiber surface of the fiber structure containing the short-fiber layer. You may comprise only fibers other than a fiber. Hereinafter, fibers other than the heat-adhesive fibers are also referred to as “non-heat-adhesive fibers”. Non-thermoadhesive fibers are, for example, fibers that are selected from the natural fibers, the regenerated fibers, and the synthetic fibers and that do not exhibit thermal adhesiveness in the process of manufacturing a conductive fiber structure, and carbon fibers. When synthetic fibers are used as non-thermoadhesive fibers, the fiber cross-sectional shape, the type and number of synthetic resins, and the composite fibers composed of multiple resin components, the combination of synthetic resins and the composite form of the constituent resins are There is no particular limitation.

  The fiber diameter and fiber length of the non-thermoadhesive fiber and the composite ratio in the case of a composite fiber are not particularly limited. However, if the fiber diameter and fiber length of the non-thermoadhesive fiber are significantly different from those of the thermoadhesive fiber, the productivity of the short fiber layer may be lowered, and the effect of the present invention may be impaired. is there. Therefore, the fiber diameter of the non-thermoadhesive fiber is also preferably 5 μm or more and 80 μm or less, more preferably 8 μm or more and 50 μm or less, particularly preferably 10 μm or more and 35 μm, and more preferably 15 μm or more and 25 μm or less. Most preferably.

  The fiber length of the non-thermoadhesive fiber is preferably 20 mm or more and 110 mm or less, more preferably 25 mm or more and 85 mm or less, particularly preferably 30 mm or more and 80 mm or less, 42 mm or more and 64 mm or less. Most preferably: The range of the fiber length of the preferable non-heat-bondable fiber by the manufacturing method of the short fiber layer is the same as that of the heat-bondable fiber.

The basis weight of the short fiber layer is not particularly limited, but the basis weight of the short fiber layer is preferably 3 g / m ² or more and 100 g / m ² . When the basis weight of the short fiber layer is 3 g / m ² or more, the resulting conductive fiber structure is bulky and excellent in mechanical properties. When the basis weight of the fiber web is 100 g / m ² or less, the resulting conductive fiber structure can have an appropriate thickness, and the handleability and post-processability can be good. Basis weight of the short fiber layer is 5 g / m ² or more, more preferably 80 g / m ² or less, 10 g / m ² or more, particularly preferably at 70 g / m ² or less, 10 g / m ² or more, 50 g / Most preferably m ² or less.

  When the conductive fiber structure of the present invention is subjected to heat treatment to form a metal porous structure, and this metal porous structure is filled with an active material mixture to produce a battery electrode material, the short fiber layer is The heat-adhesive conjugate fiber whose core component is made of a polyester resin and whose sheath component is made of polyethylene is preferably 20% by mass or more, more preferably 50% by mass or more, particularly preferably 80% by mass or more, and most preferably 100%. Including mass%. The polyester resin is preferably polyethylene terephthalate. The polyethylene is preferably high density polyethylene.

  In the manufacturing process, the battery electrode material is subjected to a thickness adjustment step and processed to have a uniform thickness. Therefore, it is desirable that the conductive fiber structure or the metal porous structure produced therefrom has a certain amount of bulk and can be compressed. Use of heat-adhesive conjugate fibers with a core / sheath made of polyester resin / polyethylene makes it possible to realize a bulky conductive fiber structure that is strongly heat-bonded to each other and has high strength. It becomes easy to adjust the electrode material to a desired thickness by post-processing.

  When the battery electrode material is manufactured by filling an active fiber mixture in a conductive fiber structure (that is, when the heat-dissipating material is not removed), the heat-adhesive conjugate fiber has both a core component and a sheath component. It is preferable that it consists of polyolefin resin. This is because the battery electrode material is generally used by being immersed in an alkaline solution or an organic solvent. A preferred core / sheath combination is, for example, polypropylene / high density polyethylene.

  When the conductive fiber structure itself of the present invention itself or a metal porous structure is filled with an active material mixture to obtain a battery electrode material, the fiber diameter of the heat-adhesive fiber is 10 μm or more. 35 μm or less, preferably 15 μm or more and 30 μm or less. When the fiber diameter of the heat-adhesive fiber is less than 10 μm, the surface area of the fiber is increased in the short fiber layer having a predetermined basis weight, so that more metal is required to obtain a metal film having a predetermined thickness. This can make it difficult to obtain a metal film of the desired thickness. Moreover, when a short fiber layer is comprised with a fiber with a small fiber diameter, a fiber density will become high and a desired quantity of active material mixture may not be filled. Furthermore, if the fiber diameter of the heat-adhesive fiber is small, the fiber diameter of the metal fiber obtained in the metal porous structure is also small, and the metal fiber is easily broken. Or may cause dendrites in the battery.

  On the other hand, when the fiber diameter of the heat-adhesive fiber exceeds 35 μm, the formation of the short fiber layer is deteriorated, that is, the uniformity is lowered. Therefore, an active material mixture is added to the conductive fiber structure or the metal porous structure. When filling, the active material mixture may fall off in rough parts.

  When manufacturing the battery electrode material, when the short fiber layer contains non-thermo-adhesive fibers, the preferred fiber diameter is the same as that of the thermo-adhesive fibers. If there is a difference in the fiber diameter between the heat-adhesive fiber and the non-heat-adhesive fiber, the productivity of the short fiber layer may be lowered, and the active material mixture may not be uniformly filled.

In the case of constituting a battery electrode material, it is necessary to reduce the thickness of the battery electrode material to ensure the winding property, and therefore it is necessary to reduce the basis weight of the short fiber layer to some extent. When the conductive fiber structure of the present invention itself or a metal porous structure thereof is filled with an active material mixture to form a battery electrode material, the basis weight of the short fiber layer is 10 g / m ² or more, It is preferably 70 g / m ² or less, more preferably 10 g / m ² or more and 50 g / m ² or less. When the basis weight is within this range, the active material mixture can be satisfactorily filled. Moreover, the handleability and post-processability of the conductive fiber structure are not impaired. If the basis weight of the short fiber layer is too small, unevenness may occur in the short fiber layer, and hence the fiber structure, and the active material mixture may fall off when filling the active material mixture. In addition, when the basis weight is small, the mechanical strength of the obtained conductive fiber structure becomes small, and breakage or the like may occur during the production of the battery electrode material. Furthermore, if the basis weight of the short fiber layer is too small, the resulting conductive fiber structure may be reduced in volume and difficult to be processed to a desired thickness.

  If the basis weight of the short fiber layer is too large, the resulting conductive fiber structure may be inferior in handleability and post-processability, and the winding property of the battery electrode material may be reduced. Moreover, when the fabric weight of a short fiber layer is too large, it will become difficult to fill an active material mixture, and the battery electrode material with which the desired amount of active material mixture was filled may not be obtained.

When the conductive fiber structure of the present invention itself or a metal porous structure is filled with an active material mixture to form a battery electrode material, the specific volume of the short fiber layer is preferably 5 cm. ³ / g or more and 80 cm ³ / g or less, more preferably 10 cm ³ / g or more and 70 cm ³ / g or less. When the specific volume is within this range, the active material mixture can be filled efficiently and sufficiently. When the specific volume of the short fiber layer is too small, the gap between the constituent fibers becomes small, and a sufficient amount of the active material mixture may not be filled in the conductive structure or the metal porous structure. When the specific volume of the short fiber layer is too large, gaps between the constituent fibers become large, and the active material mixture may fall off when filling the active material mixture.

Next, the conductive fiber structure of the present invention including the short fiber layer and the long fiber sheet and having a metal film formed on the fiber surface will be described.
The conductive fiber structure may be manufactured by a method of forming a metal film on the fiber surface after integrating the short fiber layer and the long fiber sheet, or the fibers of the short fiber layer and the long fiber sheet. After forming a metal film on the surface, they may be laminated and preferably integrated. From the viewpoint of processability and electrical characteristics, the conductive fiber structure is a laminate in which the short fiber layer and the long fiber sheet are first integrated (hereinafter referred to as the short fiber layer and the long fiber before forming the metal film). It is preferable to produce the laminate including a sheet-like material by a method of forming a metal film on the fiber surface after obtaining a laminate (also referred to as “laminated fiber structure”).

  In the laminated fiber structure, the short fiber layer and the long fiber sheet are integrated by interlacing of fibers. The treatment for integrating the fiber web and the long fiber sheet is not particularly limited, and the fiber web and the long fiber sheet are integrated by a known method. The integration may be performed, for example, by a process of confounding and integrating the constituent fibers by a physical impact such as a process using a hydroentanglement method in which the constituent fibers are entangled and integrated with a high-pressure water stream or a needle punch method. The process of confounding and integrating the constituent fibers by physical impact simultaneously performs the integration of the short fiber layer and the long fiber sheet and the confounding of the constituent fibers of the short fiber layer to give a laminated fiber structure. In addition to these entanglement processes, a process such as a thermal bond, a chemical bond, or a stitch bond may be performed.

  The hydroentanglement method using a high-pressure water stream as a physical impact is more preferable because the fibers are strongly entangled with each other. When using the water entangling method, a known method can be used, and an appropriate water pressure, the number of times of jetting the water flow, the diameter and interval of the nozzles for jetting the water flow are selected. In addition, during the hydroentanglement treatment, if necessary, so-called patterning may be performed to give a specific shape to the laminated fiber structure, or openings may be provided in the laminated fiber structure by high-pressure water flow. .

  In producing the conductive fiber structure according to the present invention, the hydroentanglement process in which the fiber web and the long fiber sheet are entangled and integrated to form a laminated fiber structure can be carried out under the following conditions, for example. it can. First, a laminate of a fibrous web and a long fiber sheet is placed on a plain mesh support of 80 mesh to 100 mesh, and an orifice having a pore diameter of 0.05 mm or more and 0.5 mm or less is 0.5 mm or more. Columnar water flow with a water pressure of 0.1 MPa or more and 10 MPa or less, preferably a water pressure of 0.5 MPa or more and 5 MPa or less, particularly preferably a water pressure of 0.7 MPa or more and 3.0 MPa or less from a nozzle provided at intervals of 5 mm or less. May be carried out by spraying onto the laminate. The columnar water stream may be jetted only on the front surface, only on the back surface, or both on the front and back surfaces, and is not particularly limited as long as the number of times of spraying is 1 or more and 5 or less. Thus, it is preferable to inject a high-pressure water flow of 0.7 MPa or more and 3.0 MPa or less once or twice on the front surface and the back surface, respectively. In the laminated fiber structure in which the columnar water stream is jetted, the short fibers constituting the fiber web are arranged so that the fiber length direction is perpendicular to the thickness direction. In the conductive fiber structure provided with a metal film on the laminated fiber structure, and the metal porous structure obtained by firing the structure, the metal-coated fiber end and the metal fiber end are not upright, and the needle-like structure Protrusion is unlikely to occur. Therefore, when these are filled with an active material, various electrode materials in which dendrite is hardly generated can be easily obtained as compared with an electrode material using a conventional urethane foam. Accordingly, when the conductive fiber structure of the present invention is used for various electrode materials, it is preferable to use a laminated fiber structure in which a columnar water stream is jetted under the above conditions. It is preferable to perform a hydroentanglement treatment, and the laminate of the entangled / integrated fiber web and the long fiber sheet is subjected to a drying / thermal bonding treatment under the conditions described later.

  As long as the conductive fiber structure of the present invention has at least one short fiber layer and at least one layer composed of a long fiber sheet, the number of layers and the stacking order are not particularly limited. Preferably, the laminated fiber structure is formed by selecting the number of layers and the order of lamination so that the layers constituting both surfaces are short fiber layers. This is because, in a laminated fiber structure, when at least one of the layers constituting both surfaces is a long fiber sheet, the long fiber sheet that has become the surface layer is easily peeled from the short fiber layer. . In particular, the laminated fiber structure is particularly preferably a laminate having a three-layer structure in which a long fiber sheet is used as an intermediate layer and short fiber layers are disposed on both surfaces thereof.

  In a laminated fiber structure, when at least one of a short fiber layer and a long fiber sheet is provided with a plurality of layers, the layers to be laminated may be the same layer, or layers having different configurations and / or characteristics. There may be. For example, when two or more short fiber layers are laminated, the short fiber layers may have different constituent fiber materials, fiber diameters, and / or fiber lengths, and / or have different basis weights. Good. When two or more long fiber sheet materials are laminated, the long fiber sheet materials may have different constituent fiber materials, fiber diameters, and / or manufacturing methods, and / or areal weight and area of openings. May be different.

  In the laminated fiber structure, the short fiber layer includes heat-bonding fibers, and the fibers constituting the short fiber layer and / or the fibers constituting the short fiber layer and the long fibers constituting the long fiber sheet-like material are thermally bonded. It is preferable. When fibers are thermally bonded to each other in a laminated fiber structure, a continuous fiber network formed by bonding points of fibers is formed, and better electrical conductivity, high tensile strength, and bulkiness can be obtained. it can. There is no particular limitation on the timing for performing the thermal bonding treatment. For example, after laminating the short fiber layer on the long fiber sheet, the laminated fiber structure obtained by performing the heat bonding treatment may be subjected to a treatment for forming a metal film as it is. Alternatively, after the short fiber layer and the long fiber sheet are integrated by the hydroentanglement method, the heat bonding treatment may be performed. In that case, the thermal bonding treatment may be performed after drying the laminated fiber structure after the hydroentanglement treatment at a relatively low temperature (a temperature at which the thermal adhesion fiber is not thermally bonded), or after the hydroentanglement treatment. It may be carried out simultaneously with the drying process. That is, a thermal bonding process may be performed in the drying process.

  The heat bonding treatment temperature is not particularly limited, and is performed at a temperature at which at least a part of the heat bonding fibers constituting the short fiber layer and / or the long fiber sheet is melted. When the heat-adhesive fiber is a composite fiber, it is preferable to perform the heat-adhesion treatment at a temperature higher by 10 ° C. or more than the melting point of the low melting point synthetic resin. For example, the heat bonding treatment temperature is preferably 100 ° C. or higher and 200 ° C. or lower, more preferably 110 ° C. or higher and 180 ° C. or lower, particularly preferably 120 ° C. or higher and 170 ° C. or lower, 120 Most preferably, it is not lower than 160 ° C and not higher than 160 ° C.

The basis weight of the laminated fiber structure is not particularly limited, and is preferably 10 g / m ² or more and 150 g / m ² or less, for example. When the basis weight of the laminated fiber structure is 10 g / m ² or more, the obtained conductive fiber structure is not only excellent in mechanical properties, but also has a large inter-fiber gap and becomes bulky. When the basis weight of the laminated fiber structure is 150 g / m ² or less, it can be avoided that the laminated structure itself becomes excessively thick and / or the inter-fiber void is excessively small and dense. Moreover, it has moderate softness. Such a laminated fiber structure has good handleability and post-processability. The basis weight of the laminated fiber structure is more preferably 15 g / m ² or more and 100 g / m ² or less, particularly preferably 20 g / m ² or more and 70 g / m ² or less, 25 g / m ² or more, Most preferred is 60 g / m ² or less.

  When the conductive fiber structure of the present invention itself or a metal porous structure is filled with an active material mixture to obtain a battery electrode material, the basis weight of the laminated fiber structure is within these ranges. It is desirable to satisfy. This is because the ease of filling and the filling amount of the active material mixture are related to the basis weight of the laminated fiber structure. If the basis weight is too small, the active material mixture may fall off when filling the active material mixture, and the active material mixture may not be filled uniformly. If the basis weight is too large, a sufficient amount of the active material mixture may not be filled.

  The thickness of the laminated fiber structure is not particularly limited, but is preferably 0.2 mm or more and 10 mm or less. Considering the handleability and post-processability of the laminated fiber structure and the conductive fiber structure, the thickness of the laminated fiber structure is more preferably 0.3 mm or more and 5 mm or less, and 0.3 mm or more and 2 mm or less. It is particularly preferable that the thickness is 0.4 mm or more and 1.5 mm or less.

As an index indicating whether the laminated fiber structure is bulky and has many interfiber gaps, the density of the laminated fiber structure can be mentioned. The density of the laminated fiber structure is not particularly limited, but is preferably 0.01 g / cm ³ or more and 0.20 g / cm ³ or less. When the density is 0.01 g / cm ³ or more, handleability, post-processability, and mechanical properties are not extremely deteriorated. When the density of the laminated fiber structure is 0.20 g / cm ³ or less, the laminated fiber structure and the conductive fiber structure of the present invention are sufficiently bulky and have many interfiber spaces. The density of the laminated fiber structure 0.014 g / cm ³ or more, more preferably 0.125 g / cm ³ or less, 0.02 g / cm ³ or more, particularly preferably at 0.1 g / cm ³ or less 0.025 g / cm ³ or more and 0.1 g / cm ³ or less is most preferable.

Similar to the density of the laminated fiber structure, the specific volume of the laminated fiber structure is an index that indicates whether the laminated fiber structure is bulky and has many interfiber gaps. The specific volume of the laminated fiber structure is not particularly limited, but is preferably 5 cm ³ / g or more and 100 cm ³ / g or less. When the specific volume is 5 cm ³ / g or more, the laminated fiber structure and the conductive fiber structure of the present invention are sufficiently bulky and have many inter-fiber voids. When the specific volume is 100 cm ³ / g or less, handling property, post-processing property, and mechanical properties are not extremely deteriorated. Specific volume of the laminated fiber structure 8 cm ³ / g or more, more preferably 70cm ³ / g or less, 10 cm ³ / g or more, 50 cm ³ / g, especially preferably not more than, 10 cm ³ / g or more, Most preferably, it is 40 cm ³ / g or less.

  When the conductive fiber structure of the present invention itself or a metal porous structure is filled with an active material mixture to form a battery electrode material, the density and specific volume of the laminated fiber structure are It is desirable to satisfy the above range. This is because the ease and amount of filling of the active material mixture are related to the density of the laminated fiber structure. If the density of the laminated fiber structure is too small, the active material mixture may fall off when the active material mixture is filled, and the active material mixture may not be filled uniformly. If the density of the laminated fiber structure is too large, a sufficient amount of the active material mixture may not be filled.

  The tensile strength in the MD direction and the tensile strength in the CD direction of the laminated fiber structure are not particularly limited, but the tensile strength in the MD direction is preferably 30 N / 50 mm or more, and the tensile strength in the CD direction is 12 N / 50 mm or more. It is preferable. When the tensile strength in the MD direction and the CD direction satisfy the above ranges, the laminated fiber structure has excellent mechanical properties, and the laminated fiber structure and the conductive fiber structure of the present invention are easy to handle and post-process. It will be excellent. Moreover, the conductive fiber structure manufactured from the laminated fiber structure having such tensile strength can be less likely to break during use. The tensile strength in the MD direction is more preferably 40 N / 50 mm or more and 160 N / 50 mm or less, and particularly preferably 50 N / 50 mm or more and 150 N / 50 mm or less. The tensile strength in the CD direction is more preferably 15 N / 50 mm or more and 100 N / 50 mm or less, and particularly preferably 25 N / 50 mm or more and 80 N / 50 mm or less.

  The laminated fiber structure includes at least one layer of a long fiber sheet in which long fibers are oriented not only in one direction but also in a direction crossing one direction. Therefore, in a general fiber assembly, particularly in a nonwoven fabric produced using only a card web, the physical property value in the MD direction and the physical property value in the CD direction are different, whereas in a laminated fiber structure, those values are The difference tends to be smaller.

  Examples of the physical property values showing such a tendency include tensile strength and elongation of the laminated fiber structure. In a fiber assembly having a strong orientation in the MD direction of the constituent fibers, such as a non-woven fabric produced using only the card web, the tensile strength in the MD direction is different from the tensile strength in the CD direction due to the orientation of the constituent fibers. Compared to In such a fiber structure, for example, the ratio of the tensile strength in the MD direction to the tensile strength in the CD direction (production direction / width direction) may be about 3, which is larger when the fiber orientation becomes stronger. It may be a ratio. On the other hand, in a fiber assembly having a strong orientation in the MD direction, the MD direction elongation is smaller than the CD direction elongation, and the ratio of the MD direction elongation to the CD direction elongation (production direction). / Width direction) may be about 0.7, and if the fiber orientation becomes stronger, the ratio may be smaller.

  In the laminated fiber structure, as an index for determining the degree of orientation of the constituent fibers, the ratio of the tensile strength in the MD direction to the tensile strength in the CD direction (hereinafter, also simply referred to as “MD / CD ratio of tensile strength”), or the CD direction The ratio of the elongation in the MD direction to the elongation (hereinafter also simply referred to as “MD / CD ratio of elongation”) can be used. In the laminated fiber structure, the MD / CD ratio of tensile strength is preferably 0.7 or more and 3 or less, and more preferably 0.8 or more and 2.5 or less. In the laminated fiber structure, the MD / CD ratio of elongation is not particularly limited, and is, for example, preferably 0.7 or more and 2.5 or less, and more preferably 0.8 or more and 2 or less.

  Next, a method for obtaining a conductive fiber structure of the present invention by forming a metal film on the surface of the constituent fibers of the laminated fiber structure to impart conductivity will be described.

  The method for imparting conductivity by forming a metal film on the surface of the constituent fiber constituting the laminated fiber structure is not particularly limited, and a known method is used. Known methods include, for example, electroless plating, electrolytic plating (also referred to as “electroplating”), and plating methods such as molten metal plating, vacuum deposition methods, sputtering methods (also referred to as “sputtering methods”), Various physical vapor deposition methods such as resistance heating vapor deposition, electron beam vapor deposition, molecular beam epitaxy, and ion beam deposition, thermal chemical vapor deposition (also called “thermal CVD”), photochemical vapor deposition Chemical vapor deposition such as plasma chemical vapor deposition (also called “plasma CVD”), flame spraying, high-speed flame spraying, arc spraying, etc. These are spraying methods such as plasma spraying and line explosion spraying. In consideration of productivity and cost, a plating method is preferably used.

  First, a method for forming a metal film on the surface of the constituent fiber of the laminated fiber structure by plating will be described first. The metal to be plated is not particularly limited. Examples of the metal to be plated include gold, silver, copper, platinum, rhodium, nickel, chromium, cobalt, tin, zinc, cadmium, aluminum, titanium, manganese, iron, and lead. One or more metals selected from these metals are selected, and a metal film is formed on the fiber surface using the above-described known plating method. The plating method is preferably an electroless plating method or an electrolytic plating method. The number of times of performing the plating process is not particularly limited. The plating process may be performed once or a plurality of times. When the plating treatment is performed a plurality of times, different types of plating methods may be combined, or the same plating method may be repeated.

  The electroless plating method will be described. The electroless plating method may be performed in the procedure of first performing the catalyst step and then performing the electroless plating step. The catalyzing step is a step of imparting a catalyst to the surface of the fiber to be plated. Examples of the method for providing the catalyst include a method in which the fiber to be plated is treated with an aqueous solution of stannous chloride in hydrochloric acid and then catalyzed with an aqueous solution of palladium chloride in hydrochloric acid, or one or more of the hydrogen atoms of ammonia are hydrocarbon residues. And a method of immobilizing only with a hydrochloric acid solution containing an amine complexing agent substituted with a group and palladium chloride.

  The electroless plating step is a step of forming a metal film using an electroless plating solution containing a solvent containing a metal to be deposited and a reducing agent. You may add a complexing agent, a pH adjuster, a buffering agent, a promoter, a stabilizer, an improving agent, etc. to an electroless-plating liquid as needed. The solvent containing the metal to be deposited is not particularly limited as long as it contains a metal salt. For example, when forming a nickel film, the nickel salt is nickel sulfate, nickel chloride, nickel nitrate, nickel sulfamate, or the like, and the reducing agent is, for example, a hydrazine derivative such as hydrazine hydrochloride, hydrazine sulfate, hydrated hydrazine, or the like. Examples thereof include hydrazine, sodium hypophosphite, dimethylamine borane and the like.

  Next, the electrolytic plating method (also referred to as electroplating method) will be described. Electroplating is a method in which a metal is deposited on a cathode by electrolysis using a plating bath in which a metal salt is dissolved. Here, the cathode is made of a fiber to be plated. Further, the anode is appropriately selected according to the plating bath and the metal to be deposited.

  A plating bath used for electrolytic plating will be described. For example, when performing electrolytic nickel plating, a watt bath whose main composition is nickel sulfate, nickel chloride and boric acid, a nickel chloride and a chloride bath whose main composition is boric acid, nickel chloride, nickel sulfamate and boron. A sulfamic acid bath whose acid is the main composition, nickel borofluoride, and a borofluoride bath whose main composition is boric acid, a strike bath (wood bath) in which hydrogen chloride is further added to the chloride bath to make the bath strongly acidic, or A black nickel plating bath is used. In the electrolytic plating bath, if necessary, aromatic sulfonic acids (for example, benzenesulfonic acid), aromatic sulfonic acid amides (for example, p-toluenesulfonamide), aromatic sulfonic acid imides (for example, saccharin), etc. Primary brighteners, aldehydes (eg formaldehyde), allyl, vinyl compounds (eg allyl sulfonic acid), acetylene compounds (eg 2-butyne-1,4-diol), and nitriles (eg ethyl cyanohydrin) Secondary brighteners such as, and various surfactants may be added.

  When performing electrolytic copper plating, copper sulfate and a copper sulfate bath whose main composition is sulfuric acid, copper borofluoride, and a copper borofluoride bath whose main composition is tetrafluoroboric acid, copper cyanide, sodium cyanide, and A copper cyanide bath whose main composition is sodium hydroxide, or a copper pyrophosphate bath whose main composition is cupric pyrophosphate, potassium pyrophosphate and ammonia are used.

  When electrolytic chromium plating is performed, a sergeant bath mainly composed of chromium (VI) oxide and sulfuric acid or a hydrofluoric acid bath mainly composed of chromium (VI) oxide, sulfuric acid and silicic acid is used.

  When carrying out electrolytic galvanization, zinc sulfate bath mainly composed of zinc sulfate, aluminum sulfate, sodium chloride and boric acid, zinc chloride bath composed mainly of zinc chloride and ammonium chloride, zinc cyanide, cyanide You may use the cyanate bath whose main composition is sodium and sodium hydroxide, or the zincate bath whose main composition is zinc oxide and sodium hydroxide.

  When carrying out electrolytic tin plating, sulfuric acid baths mainly composed of tin sulfate, sulfuric acid, cresol sulfonic acid and formalin, borofluoride baths mainly composed of tin borofluoride, tetrafluoroboric acid and formalin, or stannic acid A basic tin plating bath whose main composition is potassium and potassium hydroxide may be used.

  When carrying out electrolytic gold plating, potassium cyanide cyanide and a cyan bath whose main composition is potassium cyanide, neutral bath whose main composition is potassium gold cyanide, sodium phosphate, and sodium hydrogen phosphate, Alternatively, an acidic bath mainly composed of potassium gold cyanide and citric acid may be used.

  When performing electrolytic silver plating, a strike bath whose main composition is silver cyanide, potassium cyanide, and potassium carbonate may be used.

  When electrolytic rhodium plating is performed, a sulfuric acid plating bath whose main composition is metal rhodium and sulfuric acid, or a phosphoric acid plating bath whose main composition is metal rhodium and phosphoric acid may be used.

  When electrolytic platinum plating is carried out, a phosphate bath mainly composed of platinum (IV) chloride, hydrogen phosphate amine, and ammonium hydrogen phosphate, or diaminoplatinum nitrite, sodium nitrite, ammonium nitrate, and aqueous ammonia A diaminonitrite bath, which is the main component, may be used.

The physical vapor deposition method will be described. In the vacuum deposition method, a metal, a metal compound or an inorganic compound evaporated by heating is attached to the surface of the constituent fiber of the laminated fiber structure in a vacuum adjusted to a vacuum degree of about 10 ⁻³ to 10 ⁻⁸ Pa. This is a method of forming a film. Sputtering methods include metals (for example, single metals such as nickel, aluminum, copper, titanium, silver, and gold, alloys of nickel and chromium, alloys of titanium and aluminum, and various alloys such as nickel and copper), metal compounds (for example, A target made of titanium oxide, titanium nitride) or an inorganic compound (for example, indium tin oxide (ITO), silicon oxide) is collided with an ionized rare gas element or the like, and a metal that is repelled from the target by the collision is laminated. It is a method of forming a metal film by adhering to the surface of the constituent fiber of the fiber structure. Another physical vapor deposition method is a method in which a part or all of a metal is ionized and deposited on a substrate to which a negative charge is applied by, for example, discharge plasma or electron beam.

There is no particular limitation on the mass per unit area of metal (hereinafter, also simply referred to as “amount of metal coating” per unit area) to be deposited as a metal coating on the surface of the fibers constituting the laminated fiber structure. However, the amount of the metal film per unit area is preferably 1 g / m ² or more, more preferably 2 g / m ² or more and 500 g / m ² or less. If the amount of the metal film per unit area is less than 1 g / m ² , the amount of metal adhesion becomes insufficient, and various electrical characteristics of the conductive fiber structure may be impaired, and particularly sufficient electrical conductivity is obtained. It may not be possible. Even if the metal film is formed so that the amount of the metal film per unit area exceeds 500 g / m ² , the electrical characteristics of the conductive fiber structure cannot be significantly improved. Rather, since the metal film closes the gaps between the constituent fibers, the conductive fiber structure may become hard, and the handleability and post-workability may deteriorate. Metal coating amount per unit area, 2 g / m ² or more, more preferably 480 g / m ² or less, 3 g / m ² or more, particularly preferably at 470 g / m ² or less, 4g / m ² or more Most preferably, it is 450 g / m ² or less.

The mass per unit area of the metal (metal coating amount) deposited as a metal film on the surface of the fiber constituting the laminated fiber structure is appropriately adjusted depending on the use of the conductive fiber structure or the metal porous structure. When conductive fiber structures and metal porous structures are used for applications such as electrode materials for various electricity storage devices, such as positive electrodes for nickel-hydrogen batteries filled with active material mixtures, the amount of metal film is 120 g / m ² or more. It is more preferably 480 g / m ² or less, particularly preferably 150 g / m ² or more and 470 g / m ² or less, and most preferably 180 g / m ² or more and 450 g / m ² or less. When conductive fiber structures and metal porous structures are used for various electronic parts such as electromagnetic wave sealing materials, filters, and grounding materials, the amount of metal film should be 2g / m ² or more and 200g / m ² or less. More preferably, it is 3 g / m ² or more and 150 g / m ² or less, most preferably 4 g / m ² or more and 100 g / m ² or less.

The amount of metal film (g / m ² ) per unit area is measured by the following method. First, the mass W ₁ (g) of the laminated fiber structure is measured. Next, the process which forms a metal membrane | film | coat is performed and a metal membrane | film | coat is formed in the constituent fiber surface of a laminated fiber structure. After the process for forming the metal film is performed once or a plurality of times and the process for forming the metal film is completed, the mass W ₂ (g) and the area A (cm ² ) of the obtained conductive fiber structure are calculated. taking measurement. From the measured mass W ₁ of the laminated fiber structure, mass W _{2 of} the conductive fiber structure, and area A of the conductive fiber structure, the amount of the metal film per unit area is calculated according to the following formula (4).
Metal film amount per unit area (g / m ² ) = 1 × 10 ⁴ × (W ₂ −W ₁ ) / A (4)

  The electrical resistance of the conductive fiber structure of the present invention is not particularly limited. The ratio of the electrical resistance in the MD direction to the electrical resistance in the CD direction of the conductive fiber structure (hereinafter also simply referred to as “MD / CD ratio of electrical resistance”) is preferably 0.35 or more and 3 or less. When the MD / CD ratio of the electrical resistance is within this range, the direction dependency of the electrical conduction characteristics is lowered in the conductive fiber structure. The MD / CD ratio of electrical resistance is more preferably 0.4 or more and 2.5 or less, particularly preferably 0.45 or more and 2.25 or less, and 0.5 or more and 2 or less. Is most preferred. In addition, in the conductive fiber structure of the present invention, the electrical resistance is measured in the MD direction and the CD direction of the conductive fiber structure with a frequency of 60 kHz and an auto mode using HITESTER manufactured by Hioki Electric Co., Ltd. The

  Next, the metal porous structure of the present invention will be described. The metal porous structure of the present invention is a metal porous structure composed of metal fibers. As the metal fiber, a hollow metal fiber having a wall thickness of 1 μm or more, and a short side in a fiber cross section having a short side of 2 μm or more. It contains at least one metal fiber selected from certain metal fibers. A metal porous structure composed of hollow metal fibers having a wall thickness of 1 μm or more and / or metal fibers having a short side of 2 μm or more in the fiber cross section is formed on the surface of the fiber made of a pyrolyzable material that decomposes and disappears by heating It can be easily obtained by heating and firing a fiber structure composed of conductive fibers provided with a metal film having a thickness of 1 μm or more in a reducing atmosphere. The long side of the metal fiber in the fiber cross section referred to in the present invention is a line connecting two different points on the outer periphery of the metal fiber cross section in a plane obtained by cutting the metal fiber along a plane perpendicular to the length direction of the metal fiber. This refers to the longest line segment in a minute. And the short side of the metal fiber in the fiber cross section as referred to in the present invention means that between two different points on the outer periphery of the metal fiber cross section on the surface obtained by cutting the metal fiber along a plane perpendicular to the length direction of the metal fiber. Among the connecting line segments, the longest line segment perpendicular to the long side is indicated.

  The metal porous structure of the present invention may be composed only of hollow metal fibers having a wall thickness of 1 μm or more, or may be composed only of metal fibers having a short side in the fiber cross section of 2 μm or more, or both. Good. The metal porous structure of the present invention may be provided in a compressed state as will be described later. In that case, before the compression treatment, the metal fiber which was a hollow fiber having a thickness of 1 μm or more becomes a state in which the hollow portion is lost or becomes extremely small due to compression, and the fiber regardless of whether there is a hollow or not. The short side in the cross section is a metal fiber (for example, a flat-shaped metal fiber) having a short side of 2 μm or more (that is, a dimension obtained by combining two thicknesses of 1 μm). Considering such a case, here, two types of metal fibers having different shapes or forms are specified as fibers constituting the metal porous structure.

  The metal porous structure of the present invention is composed of metal fibers that satisfy the above-mentioned thickness or short side conditions. The metal porous structure includes short metal fibers and long metal fibers having different fiber lengths. The metal porous structure includes at least one short metal fiber layer including the short metal fibers and the long metal fibers. Including at least one long metal fiber layer. The long metal fiber layer includes a long metal fiber extending continuously in one direction of the layer and a long metal fiber extending in a direction crossing the one direction. The short metal fiber layer is laminated on the long metal fiber layer, and at least a part of the short metal fiber is bonded to the long metal fiber at an intersection with the long metal fiber. The metal porous structure of the present invention comprises a long metal fiber layer in which continuously extending long metal fibers form a network in the entire metal porous structure, and a short metal fiber having a large number of fibers and forming a dense network. The layers are joined and integrated. As a result, the metal porous structure has both a continuous metal fiber network and a densely stretched metal fiber network, and exhibits excellent electrical conductivity.

  The metal porous structure of the present invention is not particularly limited as long as it has at least one short metal fiber layer and at least one long metal fiber layer. Preferably, the metal porous structure has both surfaces thereof. Is composed of a short metal fiber layer. This is because in the metal porous structure, when at least one of the layers constituting both surfaces is a long metal fiber layer, the long metal fiber layer as the surface layer is easily peeled from the short metal fiber layer. In particular, the metal porous structure has three layers in which the long metal fiber layer is present near the center of the metal porous structure (in other words, inside the metal porous structure), and the short metal fiber layer is disposed on both surfaces thereof. A structure is preferred.

  The long metal fiber layer is not particularly limited as long as it has long metal fibers that extend continuously in one direction of the metal porous structure and long metal fibers that extend continuously in a direction crossing the specific direction. The term “long continuous metal fiber” as used herein means that when a metal porous structure including the metal fiber is used in a predetermined size, the metal porous structure including the metal fiber is continuously in a predetermined direction within the metal porous structure of the size. An extending metal fiber. The long metal fiber layer constituting the metal porous structure of the present invention may be a layer having a long metal fiber continuously extending in one direction and a long metal fiber continuously extending in a direction crossing the one specific direction. Although it is not particularly limited, it is preferably a net having an opening surrounded by long metal fibers extending continuously in at least two different directions.

  When the long metal fiber layer is a net-like material, the continuously extending long metal fibers may be arranged in two different directions, or may be arranged in three or more different directions. Alternatively, they may be arranged in a completely random state. When the long metal fiber layer is a net-like material, the long metal fiber layer is preferably formed by aligning long metal fibers extending continuously in four or less different directions, and orienting in two different directions. It is particularly preferred that it be formed. When the long metal fiber layer is a net-like material, an opening surrounded by long metal fibers aligned in two or more different directions is formed. When the long metal fibers are arranged in a completely random state, the shape of the opening also becomes a random shape accordingly. As described above, the long metal fibers are preferably aligned in four or less directions, and particularly preferably aligned in two directions. Therefore, the shape of the opening is a triangle, square, rectangle, or rhombus. Are preferable, and a square, a rectangle and a rhombus are particularly preferable.

  When the long metal fiber layer is a net-like material, the direction in which the long metal fibers continuously extending in one specific direction are oriented may be any direction. Further, in the net-like object composed of long metal fibers constituting the metal porous structure of the present invention, the long metal fibers extending in the specific one direction and the long metal fibers continuously extending in the direction intersecting the one direction. And may intersect at any angle or may be joined at the intersecting point. Long metal fibers extending continuously in two different directions preferably form an acute angle of 30 ° or more and 90 ° or less, more preferably 45 ° or more and 90 ° or less, particularly preferably 60 ° or more and 90 ° or less. Intersect or join at the intersection. When the long metal fiber layer constituting the metal porous structure is a net-like material in which such an acute angle is formed and the metal fibers are oriented in two directions, the electrical characteristics and / or mechanical properties of the metal porous structure are obtained. The direction dependency of the characteristics becomes less.

  The metal fiber constituting the metal porous structure of the present invention is not limited as long as it is a metal fiber that satisfies the above-mentioned thickness or short side condition, but as the metal fiber, a thin metal fiber having a relatively small fiber diameter and It is preferable that a thick metal fiber having a relatively large fiber diameter exists. The presence of large-diameter metal fibers having a large fiber diameter in the metal porous structure leads to the presence of metal fibers having a large cross-sectional area, that is, low electrical resistance, and the electrical resistance of the entire metal porous structure tends to be low. Because. In addition, the presence of the fine metal fibers not only makes the metal porous structure flexible, but the metal metal network is densely stretched around the metal porous structure by the fine metal fibers. Moreover, when the metal porous structure containing a thin metal fiber is used for various electrode materials, the retention performance of the active material is enhanced, and the falling off of the active material is easily suppressed.

  First, the thin metal fiber will be described. The thin metal fiber constituting the metal porous structure of the present invention has a cross section of 9 μm or more and 170 μm or less and a long side of 2 μm when the surface cut by a plane perpendicular to the fiber length direction is observed. As described above, it has a short side of 100 μm or less. When the short side in the fiber cross section of the thin metal fiber is 2 μm or more, the strength of the metal porous structure becomes sufficient, and a metal porous structure having excellent processability and durability during use can be obtained. Moreover, when the long side in the fiber cross section of a thin metal fiber is 170 micrometers or less, the workability of a metal porous structure is not impaired and a weight increase is not caused. The long side in the fiber cross section of the thin metal fiber is preferably 15 μm or more and 140 μm or less, more preferably 20 μm or more and 100 μm or less, particularly preferably 25 μm or more and 80 μm or less, and 30 μm or more and 60 μm or less. And most preferred. The short side in the fiber cross section of the thin metal fiber is preferably 2 μm or more and 80 μm or less, more preferably 3 μm or more and 65 μm or less, and particularly preferably 4 μm or more and 55 μm or less. When the thin metal fiber has a shape close to a perfect circle (specifically, the long metal fiber has a long side / the short metal fiber has a short side of less than 1.1), This thin metal fiber is treated as a thin metal fiber having a perfect cross-sectional shape, and the long side of the thin metal fiber is regarded as the diameter. In this case, the fiber diameter of the fine metal fiber (that is, the diameter of the fine metal fiber, including the long side regarded as the diameter) is preferably 7 μm or more and 120 μm or less, and preferably 10 μm or more and 80 μm or less. Is more preferably 12 μm or more and 65 μm or less.

  Next, the large diameter metal fiber will be described. The large-diameter metal fiber constituting the metal porous structure of the present invention has a fiber cross-section of 35 μm to 1300 μm long side and 2 μm when a surface cut by a plane perpendicular to the fiber length direction is observed. As described above, it has a short side of 830 μm or less. When the short side of the fiber cross section of the large-diameter metal fiber is 2 μm or more, the strength of the metal porous structure becomes sufficient, and not only a metal porous structure with excellent processability and durability during use can be obtained. The electrical characteristics of the metal porous structure are likely to be good. Moreover, the workability of a metal porous structure is not impaired, and a weight increase is not caused because the long side in the fiber cross section of a large diameter metal fiber is 1300 micrometers or less. The long side of the large-diameter metal fiber is preferably 60 μm or more and 800 μm or less, more preferably 80 μm or more and 500 μm or less, particularly preferably 100 μm or more and 400 μm or less, and most preferably 150 μm or more and 350 μm or less. . The short side of the large-diameter metal fiber is preferably 2 μm or more and 500 μm or less, more preferably 3 μm or more and 300 μm or less, and particularly preferably 4 μm or more and 250 μm or less. When the large-diameter metal fiber has a shape close to a perfect circle (specifically, the long side of the large-diameter metal fiber / the large-side metal fiber having a short side of the large-diameter metal fiber of less than 1.1), This large-diameter metal fiber is handled as a large-diameter metal fiber having a perfect cross-sectional shape, and the long side of the large-diameter metal fiber is regarded as the diameter. In this case, the fiber diameter (including the long side regarded as the diameter and the diameter) of the large-diameter metal fiber is preferably 35 μm or more and 1300 μm or less, more preferably 60 μm or more and 800 μm or less, and more preferably 80 μm or more and 500 μm. Or less, and most preferably 100 μm or more and 400 μm or less.

  The possible ranges of the short side in the fiber cross section of the thin metal fiber and the short side in the fiber cross section of the large diameter metal fiber overlap. This is because when a metal porous structure is subjected to a process involving compression such as rolling or thickness processing, both the small-diameter metal fiber and the large-diameter metal fiber may be flattened by the compression. It is. That is, in the process involving compression, when the compression ratio is particularly large, both the thin metal fiber and the large metal fiber have the same thickness (that is, the short side) in the direction parallel to the compression direction. It is because it can compress until it becomes. In this case, the long side in the fiber cross section of each of the small diameter metal fiber and the large diameter metal fiber is greatly different, and the ratio of the long side of the small diameter metal fiber to the long side of the large diameter metal fiber is specifically: Long side of diameter metal fiber): (Long side of large diameter metal fiber) = 1: 1.5 to 1:30, more preferably 1: 2 to 1:20, particularly preferably 1: 3 to 1:10 Become.

  Although the fiber length of the said thin metal fiber and the said large metal fiber is not specifically limited, It is preferable that a thin metal fiber is a comparatively short metal fiber, and a large diameter metal fiber is a comparatively long metal fiber. In other words, it is preferable that the thin metal fiber is the short metal fiber and the large metal fiber is the long metal fiber. Among the metal fibers constituting the metal porous structure of the present invention, the large-diameter metal fibers tend to have lower electrical resistance than the small-diameter metal fibers because of their large cross-sectional area. Therefore, since this is a long metal fiber continuously extending in one direction, the metal fiber having a low electrical resistance forms a conductive region with little or no cut inside the metal porous structure. It is considered that the electrical characteristics of the whole object are improved and the electrical resistance is lowered.

  When the large-diameter metal fiber is the above-described long metal fiber, the layer containing the fiber has a large-diameter metal fiber continuously extending in one direction of the layer and a large diameter extending in a direction intersecting the one direction. Contains metal fibers. The large-diameter metal fiber is not limited as long as it is a metal fiber continuously extending in the two directions, but is preferably a continuous fiber (filament) of a large-diameter metal fiber that is continuous in two directions. It is particularly preferable that the continuous fibers of large-diameter metal fibers extending in the direction have a net shape. When continuous large-diameter metal fibers are in a net shape, the large-diameter metal fibers continuous in one direction are preferably arranged at substantially equal intervals. In that case, the interval between the large-diameter metal fibers is preferably 1 mm or more and 15 mm or less, more preferably 2 mm or more and 10 mm or less, and particularly preferably 3 mm or more and 9 mm or less.

  In the metal porous structure of the present invention, as described above, it is preferable that small-diameter metal fibers and large-diameter metal fibers exist. Among these, at least a part of the small-diameter metal fiber is bonded at the intersection with the large-diameter metal fiber. Because at least a part of the thin metal fiber is joined and integrated with the large metal fiber at the intersection, the current flowing through the thin metal fiber flows through a portion with a larger fiber diameter, that is, a lower electrical resistance. As a result, it is considered that the electrical resistance of the metal porous structure is lowered.

  As long as the said large diameter metal fiber exists with a thin metal fiber in a metal porous structure, it may exist anywhere in a metal porous structure, and may exist in the surface vicinity or the surface. The large-diameter metal fiber is preferably present inside the metal porous structure (in other words, not exposed on the surface), and more preferably present in the vicinity of the center of the metal porous structure. Large metal fibers have a larger fiber diameter than thin metal fibers, and there are fewer joints between large metal fibers and small metal fibers than joints between small metal fibers. There exists a tendency for joining with a diameter metal fiber to become weaker than joining between small diameter metal fibers. Therefore, when a large-diameter metal fiber is present on the surface of the metal porous structure, there is a possibility that the connection with the fine-diameter metal fiber is released and the fine-diameter metal fiber falls off. In addition, since the large-diameter metal fiber is present near the center in the thickness direction of the metal porous structure, the large-diameter metal fiber has a small-diameter metal fiber constituting one surface and a small-diameter constituting the other surface. Since both metal fibers can be easily joined, it is considered that the electrical characteristics of the obtained metal porous structure are easily improved.

  In the metal fiber constituting the metal porous structure of the present invention, the cross-sectional shape is not particularly limited. Therefore, any cross-sectional shape can be used. For example, in addition to a circular (perfect circle) cross-section, the cross-sectional shape may be a non-circular cross-section, that is, a so-called irregular cross-section. As an irregular cross section, a polygonal shape, an elliptical shape, a flat shape, a so-called multileaf shape (specifically, a multileaf shape of 3 to 32 leaves) having a number of branch portions on the fiber surface, Examples are a star shape, a C shape, a Y shape, a W shape, and a well shape.

  The metal porous structure is composed of the metal fiber having the above-described cross-sectional shape, and is often manufactured by performing a compression process such as a rolling process or a thickness process in order to make the thickness easy to use. When the compression treatment is performed, both the small-diameter metal fiber and the large-diameter metal fiber constituting the metal porous structure tend to be flattened. In the metal porous structure in which the conductive fiber is flattened, the long side in the fiber cross section of the thin metal fiber is preferably 15 μm to 140 μm, the short side is preferably 4 μm to 50 μm, and the long side is 25 μm to 80 μm. Hereinafter, the short side is particularly preferably 4 μm or more and 30 μm or less. In the metal porous structure in which the conductive fiber is flattened, the long side in the fiber cross section of the large-diameter metal fiber is preferably 50 μm or more and 800 μm or less, the short side is preferably 4 μm or more and 250 μm or less, and the long side is 100 μm or more. Particularly preferably, it is 300 μm or less and the short side is 4 μm or more and 200 μm or less.

  The porous metal structure of the present invention can be obtained by a heat treatment including removing a thermally decomposable substance constituting the conductive fiber structure of the present invention. The method for removing the heat-dissipating substance in the conductive fiber structure is not particularly limited. For example, the heat-dissipating substance may be removed by performing a heat treatment in an oxidizing atmosphere such as air. In this case, the metal film remaining after the heat-dissipating substance is removed must be fired in a reducing atmosphere such as hydrogen or ammonia so that the metal is reduced. Alternatively, the heat-dissipating substance may be removed by treatment at 700 ° C. to 2000 ° C. for 30 seconds to 30 minutes in an inert gas atmosphere such as nitrogen, helium, or argon.

  The heat-dissipating substance removed by heating is a fiber constituting the laminated fiber structure, and specifically, natural fiber, regenerated fiber, synthetic fiber, or carbon fiber. Substances constituting these fibers are removed from the conductive fiber structure by heating or the like by decomposition or combustion. After removal of the heat-dissipating substance, the metal film covering the fiber surface remains as a skeleton, and the remaining metal film forms a metal fiber by following the fiber before disappearance. In addition, the inter-fiber voids in the laminated fiber structure are maintained even after removal of the heat-dissipating substance to give fine pores. Thus, after removing the heat-dissipating substance from the conductive fiber structure, a metal porous structure made of metal fibers is formed. When the metal film is formed after producing the laminated fiber structure, the whole is covered with the metal film at the intersections and joining points of the fibers. Therefore, at the intersections and junctions between the metal fibers of the metal porous structure, the intersecting individual fibers are unclear and the metal fibers are integrated.

  The battery electrode material of the present invention will be described. The battery electrode material has a core body filled with an active material mixture. In the battery electrode material of the present invention, the core is the conductive fiber structure of the present invention or a metal porous structure obtained therefrom. The active material mixture includes active material particles, additive particles for improving the characteristics of the electrode, active material particles, and a binder for binding the additive particles to the core.

  When the battery electrode material is a positive electrode material of a nickel metal hydride battery, the active material particles are nickel hydroxide particles. The nickel hydroxide particles may be higher-order nickel hydroxide particles having an average nickel valence of greater than 2. Further, the nickel hydroxide particles may be solid-solved with cobalt, zinc, cadmium, or the like, or the surface may be coated with a cobalt compound.

  The additive is selected from, for example, yttrium oxide; cobalt compounds such as cobalt oxide, metal cobalt, and cobalt hydroxide; zinc compounds such as metal zinc, zinc oxide, and zinc hydroxide; and rare earth compounds such as erbium oxide. .

  As the binder, a hydrophilic or hydrophobic polymer can be used. Specifically, one or more polymers selected from hydroxypropyl cellulose (HPC), carboxymethyl cellulose (CMC), and sodium polyacrylate (SPA) can be used. For example, the binder may be used in an amount of 0.1 parts by mass or more and 0.5 parts by mass or less with respect to 100 parts by mass of the active material particles.

  The filling of the active material mixture is a method in which the above components are dispersed in ion-exchanged water to prepare a paste, and a pressure is applied by immersing the core in this paste-like material, and the paste is pressed from the surface of the core, Or you may implement by the method of spraying a paste on the surface of a core. The paste is preferably prepared and filled so as to have a viscosity of 1 Pa · s to 10 Pa · s. When a paste having a low viscosity is used, it is difficult to fill a desired amount of the active material mixture because the concentration of the active material mixture is small. When the viscosity is too large, the paste is not sufficiently filled in the core body, and it is difficult to fill the active material mixture in a desired amount. The conductive structure of the present invention and the metal porous structure formed therefrom are particularly suitable for filling pastes with a viscosity in this range.

  The core after the paste filling is usually subjected to a drying process and a rolling process using a roll. In this way, a battery electrode material can be obtained. The battery electrode material is provided with a current collector and cut into a predetermined size to obtain an electrode. When this electrode is sealed in a battery container together with other parts or elements (an electrode paired with this electrode (usually a negative electrode), a separator, and an electrolyte), a battery can be obtained.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not limited to the following Example.

  The measurement and evaluation methods for various tests in the present invention are as follows.

[Unit weight]
The basis weight (g / m ² ) of the short fiber layer and the laminated fiber structure was calculated by cutting a sample into 20 cm × 20 cm and measuring its mass.

[Thickness]
The thickness was measured using a thickness measuring machine (manufactured by Daiei Kagaku Seiki Seisakusho, THICKNESS GAUGE model CR-60A) with a load of 2.94 cN applied per 1 cm ^{2 of} the sample. From the thickness measured by this method and the basis weight of the fiber structure obtained by the above method, the density (g / cm ³ ) of the fiber structure was calculated.

[Tensile strength, elongation]
In accordance with JIS-L-1096, a sample piece having a width of 5 cm and a length of 15 cm is gripped at a spacing of 10 cm, and a tensile speed of 30 cm is used using a constant speed extension type tensile tester (Orientec Co., Ltd., UCT-1T). The tensile strength and elongation were taken as the load value and elongation rate at the time of cutting, respectively.

[Ground]
The fiber structure was visually observed and evaluated according to the following criteria.
+++: There is no unevenness and the texture is uniform.
++: Although there is some unevenness, it is difficult to distinguish and the formation is good.
+: Unevenness is noticeable, but there are no holes (discontinuous portions where no fiber is present).
-: A hole exists.

[Plating amount per unit area]
The plating amount (g / m ² ) per unit area was calculated from the formula (4) according to the method described above.

[Long and short sides of metal fibers]
The long side and the short side of the metal fiber (large diameter metal fiber / small diameter metal fiber) constituting the metal porous structure were measured by the following method.
First, the porous metal structure to be measured is cut and fixed to a holder so that the cut surface can be observed, and then the cut surface of the metal porous structure is observed with a scanning electron microscope in the fiber cross section of the metal fiber. Measure the length of the long and short sides. The long side and the short side are measured at 10 different points, and the average value is taken as the length of the long side and the short side of the sample.
The measurement of the long side and the short side in the fiber cross section of the metal fiber constituting the metal porous structure can be measured by cutting the metal porous structure and observing the cut surface, and various electrode materials filled with an active material Even so, it can be measured by observing the cut surface.

  The measurement of the long side and the short side in the fiber cross section of the metal fiber constituting the metal porous structure can be measured by cutting the metal porous structure and observing the cut surface, and various electrode materials filled with an active material Even so, it can be measured by observing the cut surface. In that case, the active material filled from various electrode materials is removed, and the extracted metal porous structure is cut and observed. Various methods for removing an active material from various electrode materials produced by filling a metal porous structure with an active material are known. A method for removing an active material by immersing the electrode material in a dilute acetic acid aqueous solution is commercially available. For example, there is a method of removing an active material with ultrasonic waves using an ultrasonic cleaner or the like. Those methods can be arbitrarily used. For example, when a dilute acetic acid aqueous solution is used, only the active material can be removed by immersing the electrode material in a dilute acetic acid aqueous solution adjusted to a concentration of 1 mol / l of acetic acid for 12 hours.

[Electric resistance]
The electrical resistance of the conductive fiber structure was measured with respect to the MD direction and the CD direction of the conductive fiber structure by using HITESTER manufactured by Hioki Electric Co., Ltd., with a frequency of 60 kHz and an auto mode.

(Production of fiber web and laminated fiber structure)
In order to produce the short fiber layer constituting the conductive fiber structure of the present invention, the following fibers were prepared, and the following sheets were prepared as long fiber sheets.

[Constituent fibers of the short fiber layer]
Fiber 1: The core component is made of polyethylene terephthalate (melting point before PET spinning: 256 ° C.), the sheath component is made of high-density polyethylene (melting point before HDPE spinning: 130 ° C.), and the core-sheath ratio of the core component to the sheath component is 44/76 (core / sheath volume ratio), a heat-adhesive core-sheath composite fiber having a concentric structure with a fiber diameter of 16 μm (2.2 dtex) and a fiber length of 51 mm.
Fiber 2: A heat-adhesive core-sheath composite fiber having the same configuration and fiber length as Fiber 1 except that the fiber diameter is 19 μm (3.3 dtex).
Fiber 3: A heat-adhesive core-sheath composite fiber having the same configuration and fiber length as Fiber 1 except that the fiber diameter is 32 μm (8.9 dtex).
Fiber 4: A heat-adhesive core-sheath composite fiber having the same configuration and fiber diameter as the fiber 1 except that the fiber length is 38 mm.

[Long fiber sheet]
Sheet 1: Polypropylene monofilaments are arranged at equal intervals in the MD and CD directions, and the monofilament in the MD direction (filament fiber diameter: 174 μm) and the CD direction monofilament (filament fiber diameter: 187 μm) are orthogonal to each other. The thickness of the portion is 298 μm (intersection portion thickness / filament fiber diameter: 1.59), the mesh is 4 mm × 4 mm, the opening area is 16 mm ² , the basis weight is 10 g / m ² , the opening Orthogonal net-like object whose shape is a square of 4 mm square (Conwed (registered trademark) net product number R03650 manufactured by JX Nippon Mining & Metals ANCI Corporation)
Sheet 2: Monofilaments made of polypropylene are arranged at equal intervals in the MD direction and the CD direction, and the monofilaments in the MD direction (monofilament fiber diameter: 338 μm) and the CD direction monofilaments (filament fine diameter: 337 μm) are orthogonal to each other. The thickness of the portion is 521 μm (intersection portion thickness / filament fiber diameter: 1.54), the mesh is 6 mm × 6 mm, the opening area is 36 mm ² , the basis weight is 19 g / m ² , the opening Orthogonal net-like object whose shape is a square of 6 mm square (Conx (registered trademark) net product number R05340 manufactured by JX Nippon Mining & Metals Corporation ANCI Corporation)

Sheet 3: Monofilaments made of polypropylene are arranged at equal intervals in the MD direction and CD direction, and the monofilaments in the MD direction (filament fiber diameter: 301 μm) and the CD direction monofilaments (filament fiber diameter: 341 μm) are orthogonal to each other. The thickness of the portion is 427 μm (intersection portion thickness / filament fiber diameter: 1.25), the mesh is 6 mm × 6 mm, the opening area is 36 mm ² , the basis weight is 33 g / m ² , the opening Orthogonal net-like object whose shape is a square of 6 mm square (Conwed (registered trademark) net product number R03018 manufactured by JX Nippon Mining & Metals ANCI Corporation)
Sheet 4: Monofilaments made of polypropylene are arranged at equal intervals in the MD direction and the CD direction, and the monofilament in the MD direction (filament fiber diameter: 220 μm) and the monofilament in the CD direction (filament fiber diameter: 167 μm) are orthogonal to each other. The thickness of the portion is 288 μm (intersection thickness / filament fiber diameter: 1.30), the mesh is 8 mm × 9 mm, the opening area is 72 mm ² , the basis weight is 5 g / m ² , the opening Orthogonal net-like object whose shape is a square of 8 mm square (Conx (registered trademark) net product number R03235, manufactured by JX Nippon Mining & Metals ANCI Corporation)

Sheet 5: Monofilaments made of polypropylene are arranged at equal intervals in the MD direction and the CD direction, and monofilaments in the MD direction (filament fiber diameter: 345 μm) and CD direction monofilaments (filament fiber diameter: 288 μm) are orthogonal to each other. The thickness of the part is 368 μm (intersection part thickness / filament fiber diameter: 1.07), the mesh is 1 mm × 1 mm, the opening area is 1 mm ² , the basis weight is 100 g / m ² , the opening Orthogonal net-like object whose shape is a 1 mm square (JX Nippon Mining & Metals ANCI Corporation Conwed (registered trademark) net product number X06065)
Sheet 6: Monofilaments made of polypropylene are arranged at equal intervals in the MD direction and the CD direction, and the monofilaments in the MD direction (filament fiber diameter: 146 μm) and the CD direction monofilaments (filament fiber diameter: 351 μm) are orthogonal to each other. The thickness of the part is 244 μm (intersection part thickness / filament fiber diameter: 0.70), the mesh is 1 mm × 4 mm, the opening area is 4 mm ² , the basis weight is 32 g / m ² , the opening Orthogonal net-like object whose shape is a rectangle of 1 mm × 4 mm (Conx (registered trademark) net product number R03330, manufactured by JX Nippon Mining & Metals ANCI Corporation)

Example 1
Using a parallel card, ^two parallel card webs having a basis weight of 15 g / m ² were produced as short fiber layers using only the fiber 1. Next, a card web made of fibers 1 was laminated as a short fiber layer on both surfaces of the sheet 1 to form a laminate having a three-layer structure in which both surfaces were card webs made of fibers 1. A hydroentanglement process using a high-pressure water stream was performed on the laminate having the three-layer structure. In the hydroentanglement treatment, a columnar water flow having a water pressure of 0.98 MPa (10 kgf / cm ² ) is applied to the laminate having the three-layer structure by using a nozzle in which orifices having a hole diameter of 0.1 mm are provided at intervals of 0.6 mm. One injection was carried out. Next, the laminate after the hydroentanglement treatment is dried at 110 ° C. using a hot air blowing type heat treatment machine, and then further subjected to heat treatment at 140 ° C. for 13 seconds using a hot air blowing type heat treatment machine. Were thermally bonded to obtain a laminated fiber structure.

The obtained laminated fiber structure was cut into a size of 17.6 cm × 28 cm, and a catalyst treatment (catalyst) using a solution containing stannous chloride, palladium chloride and the like was performed on the laminated fiber structure. Then, in addition to a water-soluble nickel compound, an electroless nickel plating solution containing a known complexing agent and reducing agent is impregnated with the laminated fiber structure that has been subjected to the catalytic treatment, electroless plating is performed, and nickel is applied to the fiber surface. A film was formed to obtain a conductive fiber structure. In this conductive fiber structure, the amount of nickel attached to the fiber surface was 0.111 g, and the plating amount per unit area was 4.53 g / m ² .

(Examples 2 to 12)
The laminated fiber structure is the same as the procedure adopted when producing Example 1, except that the fibers constituting the short fiber layer and the long fiber sheet are changed to those shown in Tables 1 and 2, respectively. In addition, a conductive fiber structure was obtained.

(Comparative Example 1)
Using a parallel card, a web composed of a single layer of fiber 1 having a basis weight of 30 g / m ² was produced using only fiber 1 described above. The web was subjected to hydroentanglement treatment using a high-pressure water stream. In the hydroentanglement treatment, a columnar water flow having a water pressure of 0.98 MPa (10 kgf / cm ² ) is sprayed once toward the web using a nozzle having orifices with a hole diameter of 0.1 mm provided at intervals of 0.6 mm. Carried out. Next, the web after the hydroentanglement treatment is dried at 110 ° C. using a hot air blowing type heat treatment machine, and further subjected to heat treatment at 140 ° C. for 13 seconds using a hot air blowing type heat treatment machine, thereby separating the constituent fibers. A single-layer fiber structure was obtained by heat bonding. A nickel film was formed on the fiber surface of the obtained fiber structure to obtain a conductive fiber structure. The nickel film was formed by the same procedure as that adopted in Example 1.

(Comparative Examples 2 to 5)
A laminated fiber structure was obtained in the same procedure as that used when producing Comparative Example 1 except that the used fiber was changed to that shown in Table 2, and a conductive fiber structure was obtained.

  About the obtained conductive fiber structure of Examples 1-12 and the conductive fiber structure of Comparative Examples 1-5, the plating amount per unit area, the electrical resistance of MD direction, the electrical resistance of CD direction by the above-mentioned method The MD / CD ratio of electrical resistance was measured and evaluated. Moreover, with these results, in each of the examples and comparative examples, the laminated fiber structures of Examples 1 to 12 and the single layers of Comparative Examples 1 to 5 were measured before the treatment for forming the metal film on the constituent fiber surface. Tables 1 and 2 show the basis weight, thickness, density, specific volume, MD direction, tensile strength in the CD direction, and MD / CD ratio of tensile strength of the structural fiber structure. Furthermore, the scanning microscope picture which image | photographed the surface of the conductive fiber structure of Example 2, 7 is shown to FIGS.

  As shown in Tables 1 and 2, the conductive fiber structures of Examples 1 to 12 having a three-layer structure in which the middle layer is a long fiber sheet-like material are electrically conductive with a single layer structure produced using the same short fibers. As compared with the conductive fiber structure, the electrical resistance in at least one of the MD direction and the CD direction was low. This is considered to be because the short fibers are entangled well due to the presence of the long fiber sheet.

  Comparing Example 4 and Example 6 using orthogonal nets having the same scale but different monofilament (long fiber) fiber diameters, Example 4 shows a lower total electrical resistance. It was. The total sum of electric resistances is the sum of the electric resistance value in the MD direction and the electric resistance value in the CD direction. This is because if the fiber diameter of the long fibers is thick, the fibers in the short fiber layer are not easily entangled with the long fibers, or the fibers in the short fiber layer are not easily entangled with each other, and the continuity of the metal film is slightly reduced. It is thought that.

  The mechanical properties of the fiber structure before forming the metal film will be considered. In Comparative Examples 1, 2, and 3, the tensile strength in the MD direction was high, the tensile strength in the CD direction was extremely lower than that in the MD direction, and the MD / CD ratio of tensile strength was larger than 3. On the other hand, the laminated fiber structures used in the examples had a difference in tensile strength between the MD direction and the CD direction by inserting a long fiber sheet into the middle layer, and both were less than 3. It was. Therefore, the laminated fiber structures of these examples were easy to handle and easy to handle even after the metal film was formed.

  In addition, the example includes a good thing and a bad thing. Those having good formation are preferably used for forming an electrode material and a heat-resistant filter having high filtration accuracy. Those with poor formation can also be used in applications where the formation does not affect the quality of the product, such as a coarse dust filter, or where it is desired that the formation be dense.

  The conductive fiber structure of the example and the conductive fiber structure of the comparative example are compared. In the laminated fiber structure before forming the nickel film, the laminated fiber structures of Comparative Examples 1 to 5 have a large tensile strength MD / CD ratio and are dependent on the direction of the tensile strength. 12 of them have MD / CD close to 1. This is thought to be because the direction dependency of the short fiber layer was relaxed by including the long fiber sheet composed of long fibers extending in two or more different directions in the fiber structures used in Examples 1-12. In addition, since the direction dependency of the mechanical properties of the laminated fiber structure is small, the processability and handleability when producing the conductive fiber structure are improved, and the strength of the conductive fiber structure is increased depending on the direction. Since there is no difference, it is considered that the handleability of the conductive fiber structure is improved.

  When comparing the conductive fiber structure of Examples 1 to 12 and the conductive fiber structure of the comparative example, the conductive fiber structure of the comparative example has a value obtained by adding up the electric resistance in the MD direction and the CD direction to 3.2Ω. In contrast, all the conductive fiber structures of the present invention are less than 3Ω. This is presumably because the conductive fiber structure of the present invention includes a long fiber sheet-like material, thereby forming a continuous conductive region therein, thereby reducing the electrical resistance. In the conductive fiber structures of Examples 1 to 12, the electric resistance in either the MD direction or the CD direction is less than 1.8Ω, and the MD / CD ratio of the electric resistance is 0.4 or more and 1.5 or less. Range. From this, it can be confirmed that the electrical characteristics of the conductive fiber structure of the present invention are less directional dependent. This is considered because the conductive fiber structure of the present invention includes a long fiber sheet extending in two different directions.

(Production of porous metal structure electrode material)
The fiber structure produced in Example 7 and Comparative Examples 1, 2, 4, and 5 and the fiber structure of Example 13 were newly prepared to produce battery electrode materials.

(Example 13)
First, the fiber structure of Example 13 will be described. Using a parallel card machine, a parallel card web having a basis weight of 15 g / m ² was produced as a short fiber layer using only the fiber 2. Next, the sheet 1 was placed on the card web made of the fibers 2. A parallel card web made of the fibers 2 and having a basis weight of 15 g / m ² was further laminated on the sheet 1 to produce a laminate having a three-layer structure in which the sheet 1 was arranged at the center. . A hydroentanglement process using a high-pressure water stream was performed on the laminate having the three-layer structure. In the hydroentanglement treatment, a columnar water flow having a water pressure of 1.47 MPa (15 kgf / cm ² ) is applied to the laminate having the three-layer structure by using a nozzle in which orifices having a hole diameter of 0.1 mm are provided at intervals of 1.0 mm. After spraying once on the laminate having the three-layer structure, a columnar water flow having a water pressure of 2.45 MPa (25 kgf / cm ² ) was sprayed once on the same surface. Next, the laminate after the hydroentanglement treatment was heat-treated at 135 ° C. using a hot air blowing type heat treatment machine, and the constituent fibers were thermally bonded simultaneously with drying to obtain a laminated fiber structure.

The fiber structure manufactured in Example 7 and Comparative Examples 1, 2, 4, and 5 and the fiber structure of Example 13 manufactured by the above manufacturing method were subjected to sputtering treatment using metallic nickel as a target, and the fiber structure A nickel film was formed on the surface of the constituent fibers of the article. Sputtering was performed by ion beam sputtering using argon gas, and a uniform nickel film was formed on the constituent fiber surfaces of the fiber structure. The conductive fiber structure was subjected to nickel plating using a watt bath mainly composed of nickel sulfate and nickel chloride and nickel metal as an anode to obtain a conductive fiber structure. Nickel plating was performed for Example 7 and Comparative Examples 1, 2, 4, and 5 so that the amount of nickel per unit area was 400 g / m ² . For Example 13, the nickel amount per unit area was 350 g / m ² . Next, the conductive structure was subjected to heat treatment to remove the heat-dissipating substance constituting the fiber structure to obtain a metal porous structure. Thereafter, the conductive fiber structure was processed to have a thickness of 1.5 mm. In the heat treatment, after removing the heat-dissipating substance at 600 ° C., nickel was reduced under a reducing atmosphere at 1000 ° C. (using ammonia decomposition gas or the like).

  A paste containing nickel hydroxide as active material particles, cobalt hydroxide as an additive, and hydroxypropyl cellulose (HPC) as a binder was applied to the obtained metal porous structure, and the active material mixture was filled. The paste was applied by continuously immersing the metal porous structure in a paste having a viscosity of 4 Pa · s. After applying the paste, it was dried and rolled to obtain a battery electrode material having a predetermined size.

  Using the obtained electrode material of Example 7 and Comparative Example 2, the metal fibers of the metal porous structure constituting the electrode material were observed, and the lengths of the fiber cross-sections of the large-diameter metal fiber and the small-diameter metal fiber were respectively long. Sides and short sides were measured. As described above, first, after removing the active material filled in the metal porous structure and taking out the metal porous structure, the taken metal porous structure is cut and the cut surface is observed with a scanning electron microscope. And measured. The results are shown in Table 3.

  In the obtained battery electrode material, the mass of the active material particles per unit area was measured. The mass of the active material particles is measured by a method of measuring the mass of the active material particles per unit area at intervals of 5 m after drying a metal porous structure continuously immersed in a paste having a viscosity of 4 Pa · s. did. From the measured values, the standard deviation of the mass of the active material particles per unit area and the difference between the maximum value and the minimum value were determined. The results are shown in Table 3. The smaller the standard deviation and the difference between the maximum value and the minimum value, the more uniformly the active material particles are filled, indicating that a battery electrode material having uniform characteristics was obtained.

  When Example 7 and Example 13 which are the electrode materials of the present invention are compared with the electrode material of the comparative example, the difference between the maximum value and the minimum value of the amount of filled active material is greater than that of the electrode material of the comparative example. The electrode material is smaller. Therefore, when the conductive fiber structure and the metal porous structure of the present invention are used, an electrode material with more stable active material filling and uniform performance of the electrode material can be easily produced than those of the prior art. The reason why the active material filling amount is stabilized in the electrode material of the present invention cannot be specified. One possible reason is that when a metal porous structure manufactured using the conductive fiber structure of the present invention is coated with a paste containing an active material and filled with the active material, continuous long metal fibers (Examples) In this case, the void shape of the metal porous structure is less likely to be crushed, and the filling of the active material is less likely to vary depending on the location, or the active material is less likely to fall off due to the continuous metal fiber. It is.

  From FIG. 5 in which the surface of the metal porous structure was observed, it can be confirmed that long metal fibers are continuously present in the metal porous structure in the metal porous structure of the present invention. From this, it can be considered that the continuous long metal fiber brings good electrical characteristics to the metal porous structure in the extending direction of the continuous fiber. And it is thought that the continuous long metal fiber is oriented in two or more different directions, thereby suppressing the bias (anisotropy) of the electrical characteristics. Moreover, it is confirmed from FIG.6 and FIG.8 that the short metal fiber which is a thin metal fiber is joined with the long metal fiber which is a large diameter metal fiber. Therefore, the metal porous structure of the present invention has a relatively small fiber diameter, a tightly packed thin metal fiber, and a large-diameter metal fiber having a large cross-sectional area and a small electric resistance joined at many intersections. Thus, a metal porous structure in which a thin metal fiber and a large metal fiber are integrated, and this metal porous structure can be easily obtained by using the conductive fiber structure of the present invention. .

  Moreover, from FIG. 5, in the metal porous structure of this invention, it can confirm that the edge part by which the frame | skeleton part seen in the metal porous structure using the conventional foaming urethane was cut | disconnected was hardly formed. In addition, the fiber ends are realigned so that the fibers are perpendicular to the thickness direction by jetting the columnar water flow when producing the laminated fiber structure that is the base of the metal porous structure, so that the fiber ends are aligned. It can be confirmed from FIG. 7 that the needle-like protrusions which do not stand upright and are upright in the vertical direction as seen in the conventional metal porous structure using urethane foam are not formed. From these facts, the metal porous structure or conductive fiber structure of the present invention is an electrode material that hardly forms dendrites when filled with an active material and is used for various electrode materials, and is less prone to breakage of the separator and short circuit. .

  The porous metal structure of the present invention having these characteristics is obtained by subjecting the conductive fiber structure of the present invention to electrolytic plating or heat-treating the conductive fiber structure subjected to electrolytic plating to a heat-dissipating substance. It can be easily obtained by disappearing. This is because the conductive fiber structure having at least one layer of long fiber sheet is subjected to electroplating or, in some cases, subjected to heat treatment at a temperature at which the heat-dissipating substance disappears, This is because the structure of the conductive fiber structure is maintained. 1 and 2 and the porous metal structure shown in FIGS. 5 and 6 are compared, a thick metal film is formed by electroplating, and the constituent fibers (long Although the fiber diameter of the fibers and the short fibers is changed, it can be confirmed that there is no change in the structure in which the long fibers and the short fibers are present and the structure in which the short fibers are bonded to the long fibers.

  The conductive fiber structure and metal porous structure of the present invention can be used for various electronic parts such as electromagnetic wave sealing materials, filters, accessories, and earth ground materials. In particular, by filling the conductive fiber structure and metal porous structure of the present invention with an active material mixture, various electrode material characteristics (for example, current collection characteristics) are excellent for battery electrode materials (for example, nickel-hydrogen batteries). Various electrode materials for alkaline secondary batteries and lithium ion secondary batteries) can be obtained.

Claims (21)

A conductive fiber structure in which a metal film is formed on the fiber surface of the fiber structure,
The fiber structure includes at least one short fiber layer and at least one long fiber sheet.
The long fiber sheet-like material includes long fibers continuously extending in one direction of the sheet, and long fibers continuously extending in a direction crossing the one direction,
In the fiber structure, the fibers constituting the short fiber layer, and the fibers constituting the short fiber layer and the long fibers constituting the long fiber sheet are entangled.
Conductive fiber structure.   The conductive fiber structure according to claim 1, wherein the fiber structure has a three-layer structure in which the short fiber layers are laminated on both surfaces of the long fiber sheet-like material.   The conductive fiber structure according to claim 1 or 2, wherein the long fiber sheet is a net.   The fiber diameter of the long fibers constituting the long fiber sheet-like material and continuously extending in one direction of the sheet and continuously extending in a direction intersecting the one direction is 1000 μm or less. 4. The conductive fiber structure according to any one of 3 above. The conductive fiber structure according to any one of claims 1 to 4, wherein in the long fiber sheet-like material, an opening area surrounded by the long fibers is 500 mm ² or less.   The short fiber layer includes heat-adhesive fibers, and the heat-adhesive fibers constitute fibers constituting the short fiber layer and / or fibers constituting the short fiber layer and the long fiber sheet. The conductive fiber structure according to any one of claims 1 to 5, wherein the long fiber is thermally bonded.   The conductive fiber structure according to claim 6, wherein the heat-adhesive fiber is a heat-adhesive core-sheath composite fiber in which a core component includes a polyester-based resin and a sheath component includes a polyolefin-based resin.   The conductive fiber structure according to claim 1, wherein the short fiber layer and the long fiber sheet are made of a heat-dissipating substance. Including at least one short fiber layer and at least one long fiber sheet,
The long fiber sheet-like material includes long fibers continuously extending in one direction of the sheet, and long fibers continuously extending in a direction crossing the one direction,
The fibers constituting the short fiber layer, and the fibers constituting the short fiber layer and the long fibers constituting the long fiber sheet are entangled,
A fiber structure for a conductive fiber structure. A metal porous structure composed of at least one metal fiber selected from hollow metal fibers having a wall thickness of 1 μm or more and metal fibers having a short side of 2 μm or more in the fiber cross section,
As metal fibers constituting the metal porous structure, there are short metal fibers and long metal fibers having different fiber lengths,
The metal porous structure includes at least one short metal fiber layer including the short metal fiber, and at least one long metal fiber layer including the long metal fiber,
The long metal fiber layer includes a long metal fiber continuously extending in one direction of the sheet, and a long metal fiber continuously extending in a direction intersecting the one direction,
At least a part of the short metal fiber is bonded to the long metal fiber at an intersection with the long metal fiber.   The metal porous structure according to claim 10, wherein the metal porous structure has a three-layer structure in which the short metal fiber layers are laminated on both surfaces of the long metal fiber layer.   The metal porous structure according to claim 10 or 11, wherein the long metal fiber layer is a net-like material made of the long metal fibers.   The metal porous structure according to any one of claims 10 to 12, wherein a thin metal fiber and a large metal fiber having different fiber diameters are present as the metal fiber. The metal porous structure according to claim 13 , wherein the thin metal fiber is the short metal fiber, and the large metal fiber is the long metal fiber. The fine metal fiber has a fiber cross section in which a long side is 9 μm or more and 170 μm or less, and a short side is 2 μm or more and 100 μm or less on a plane cut by a plane perpendicular to the length direction of the fiber,
The large-diameter metal fiber has a fiber cross section having a long side of 359 μm or more and 1300 μm or less and a short side of the fiber cross section of 2 μm or more and 830 μm or less on a plane cut by a plane perpendicular to the length direction of the fiber. The metal porous structure according to claim 13 or 14.   A metal porous structure formed by subjecting the conductive fiber structure according to any one of claims 1 to 8 to a heat treatment to remove a heat-dissipating substance.   An electrode for a battery, wherein the conductive fiber structure according to any one of claims 1 to 8 or the metal porous structure according to any one of claims 10 to 16 is filled with an active material mixture. Wood.   A battery comprising the battery electrode material according to claim 17 as an electrode. A short fiber layer containing a heat-adhesive fiber on at least one surface of a long fiber sheet-like material comprising a long fiber continuously extending in one direction of the sheet and a long fiber extending continuously in a direction crossing the one direction. To obtain a laminate,
Subjecting the laminate to hydroentanglement treatment to entangle the fibers constituting the short fiber layer, and the fibers constituting the short fiber layer and the long fibers constituting the long fiber sheet,
The laminate subjected to the hydroentanglement treatment is subjected to a thermal bonding treatment, and the fibers constituting the short fiber layer and / or the fibers constituting the short fiber layer and the long fibers constituting the long fiber sheet-like material A method for producing a conductive fiber structure, comprising: heat-adhering an adhesive layer with the heat-adhesive fiber; and forming a metal film on a surface of a fiber constituting the laminate subjected to the heat-adhesion treatment. Conductive fiber structure
At least one of long fibers made of a heat-dissipating substance continuously extending in one direction of the sheet and long-fiber sheet-like material comprising long fibers made of a heat-dissipating substance continuously extending in a direction intersecting the one direction Laminating a short fiber layer made of a fiber made of a heat-dissipating substance and containing a heat-adhesive fiber made of a heat-dissipating substance on the surface to obtain a laminate,
Subjecting the laminate to hydroentanglement treatment to entangle the fibers constituting the short fiber layer, and the fibers constituting the short fiber layer and the long fibers constituting the long fiber sheet,
The laminate subjected to the hydroentanglement treatment is subjected to a thermal bonding treatment, and the fibers constituting the short fiber layer and / or the fibers constituting the short fiber layer and the long fibers constituting the long fiber sheet-like material Is obtained by a method including heat-adhering with the heat-adhesive fiber, and forming a metal film on the surface of the fiber constituting the laminate subjected to the heat-adhesion treatment, and the conductive fiber structure The manufacturing method of a metal porous structure including attaching | subjecting to heat processing and removing the said heat-dissipative substance. The manufacturing method of the battery electrode material including obtaining a metal porous structure by the manufacturing method of Claim 20, and filling the active material mixture in the said metal porous structure.

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