JP5723741B2 - Porous sheet and method for producing the same - Google Patents

Description

  The present invention relates to a porous sheet made of resin fibers and a method for producing the same, and particularly to a technique for controlling the orientation of resin fibers.

  As a method for producing a porous sheet made of very thin fibers, for example, there is an electrospinning method (electrospinning method). For example, as shown in FIG. 4, a porous sheet 1 manufactured by an electrospinning method is a resin fiber sheet that generally has a nonwoven fabric shape in which fibers 2 are randomly entangled with each other. Reference numeral 3 denotes a base material.

  Such a porous sheet is used for various applications. For example, in Patent Document 1, a non-woven electrolyte resin fiber sheet (porous sheet) is applied to the catalyst layers (electrode layers) on both surfaces of the electrolyte membrane of a fuel cell, and the catalyst is adhered to the resin fiber sheet. Patent Document 1 proposes that the proton conductivity in the fiber length direction is improved and the battery performance is improved by making the electrolyte in the catalyst layer into a fibrous form.

JP 2007-220416 A

  Further, when a fiber resin sheet is applied to the catalyst layer, the resin fiber sheet is porous, so that it is easy for gases such as hydrogen and oxygen to reach the catalyst layer, and the catalyst in the catalyst layer reacts with the gas. This is considered to improve battery performance. However, since the porous sheet of Patent Document 1 is a nonwoven fabric, it has a structure in which resin fibers are randomly entangled, and the gas diffusion path in the catalyst layer becomes long. In addition, the diameters of the pores (voids) between the resin fibers became non-uniform, and it was not possible to make the gas efficiently reach the catalyst in the catalyst layer.

  Therefore, according to the present invention, the pore diameter between the resin fibers can be made uniform, the fibers can be regularly arranged, and when applied to the electrode layer of the fuel cell electrode, sufficient gas is supplied to the catalyst. It is an object of the present invention to provide a porous sheet that can be efficiently reached and a method for producing the same.

The method for producing a porous sheet of the present invention includes a nozzle that discharges a resin solution toward one surface of a substrate, and one or more direction controls provided on the other surface opposite to the one surface of the substrate. And charging the resin solution to a positive or negative charge, charging at least one of the directional control collectors to a charge different from the resin solution, and applying the charged resin solution from the nozzle to one surface of the substrate. A porous sheet made of resin fibers is formed on one surface of the substrate, and the discharge of the charged resin solution is based on the direction control collector charged to a charge different from that of the resin solution. by changing the plane position with respect to one side of the timber, to control the movement direction of the solution of the resin, to switch sequentially selects the directional control collector for charging a different charge from among the two or more directional control collector , Characterized in that to change the plane position of the directional control collector was charged to different charge.

  In the method for producing a porous sheet of the present invention, when the resin solution charged to a positive or negative charge is released, the in-plane position of the direction control collector charged to a different charge from the resin solution relative to one surface of the substrate Is changed to control the moving direction of the resin solution. Thereby, since the arrival position of the resin fiber on one surface of the substrate can be controlled, the orientation of the resin fiber can be controlled. Accordingly, since the resin fibers can be regularly arranged, the pore diameter between the resin fibers can be made uniform, and the gas diffusion path can be shortened. As a result, for example, when applied to the electrode layer of a fuel cell electrode, the gas can reach the catalyst sufficiently efficiently.

In the present invention, the in-plane position of the direction control collector charged with different charges is changed by selecting and sequentially switching the direction control collector charged with different charges from two or more direction control collectors . In this case, it is preferable to set the direction control collector switching speed at which different charges are charged to be equal to or higher than the arrival speed of the resin fibers on one surface of the substrate. In this aspect, resin fibers can be smoothly arranged in a straight line without being deposited at a predetermined location on one surface of the substrate. Further, for example, it is possible to use a mode in which the in-plane position of the direction control collector charged with a different charge is changed by moving the direction control collector charged with a different charge.

  The porous sheet of the present invention is manufactured by the method for manufacturing a porous sheet of the present invention, and includes a fiber layer in which resin fibers are oriented in a predetermined direction. The porous sheet of the present invention can obtain the same effects as those of the method for producing a porous sheet of the present invention.

  Various configurations can be used for the porous sheet of the present invention. For example, the aspect applied to the electrode for fuel cells can be used for the porous sheet of this invention. Specifically, it can be applied to an electrode layer of a fuel cell electrode or a water retention layer between the electrode layer and the diffusion layer.

  According to the porous sheet of the present invention or the method for producing the same, the pore diameter between resin fibers can be made uniform, and the fibers can be regularly arranged. For example, the electrode layer of a fuel cell electrode When applied to the above, the gas can reach the catalyst sufficiently efficiently.

An example of the apparatus used with the manufacturing method of the porous sheet of one embodiment concerning the present invention is represented, (A) is a perspective view showing the schematic structure of an apparatus, and (B) was charged in the electric charge different from a resin solution. It is the elements on larger scale showing the chronological change state of a direction control collector. The part which represents the other example of the direction control collector of the apparatus used with the manufacturing method of the porous sheet of one Embodiment which concerns on this invention, and represents the state of the spatial movement of the direction control collector charged to the electric charge different from a resin solution It is an enlarged view. It is a perspective view showing the outline composition of a part of porous sheet of one embodiment concerning the present invention, and the state formed on the substrate. It is a perspective view of the state which represents the schematic structure of a part of conventional porous sheet, and was formed on a substrate.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an example of an apparatus 100 used in the method for producing a porous sheet according to an embodiment of the present invention, (A) is a perspective view showing a schematic configuration of the apparatus 100, and (B) shows a negative charge. It is the elements on larger scale showing the time-dependent switching state of the charged direction control electrode 103A (direction control collector). The apparatus 100 is an apparatus that manufactures a porous sheet made of resin fibers 12 (fibers) using an electrospinning method.

  The apparatus 100 includes, for example, a nozzle 101, a fixing unit 102, and a collector unit 103. The nozzle 101 has a nozzle tip 101 </ b> A that discharges the resin solution 10. The nozzle tip 101A is set to a positive potential, for example, and the resin solution 10 discharged from the nozzle tip 101A is charged to a positive charge, for example. The resin of the resin solution 10 may be an electrolyte resin or a non-electrolyte resin that can be electrospun.

  The fixing unit 102 fixes the base material 13. The fixing part 102 has a pair of fixing members 102A and 102B arranged at a predetermined interval, for example. The base material 13 is an insulating film made of, for example, polyethylene terephthalate (PET). The base material 13 is fixed to the fixing members 102A and 102B so that the surface 13A faces the nozzle 101. In this case, the surface 13A (one surface) of the base material 13 is disposed so as to be perpendicular to the extending direction of the nozzle tip 101A, for example, as shown in FIG.

  The collector 103 is disposed on the back surface 13B (other surface) side of the base material 13. The collector part 103 may be in contact with the back surface 13B or may be arranged at a predetermined interval. The collector unit 103 includes a large number of direction control electrodes 103A arranged in the X direction and the Y direction to form a lattice shape. A boundary portion between the direction control electrodes 103A is insulated by an insulating portion 103B. The size of one side of the direction control electrode 103A is, for example, 5 mm or less, and the distance between the direction control electrodes 103A is set to, for example, 15 mm or less.

  The collector 103 can control the charged state of each direction control electrode 103A by using a drive circuit such as that used in a plasma display panel (PDP), for example. For example, the nozzle tip 101A is set to a positive potential, and at least one direction control electrode 103A is grounded or set to a negative potential, and the other direction control electrodes 103A are set to a positive potential. The potential difference between the nozzle tip 101A and the direction control electrode 103A charged to a negative charge is set to, for example, about 3 kV to 50 kV.

  In the control by the drive circuit, the direction control electrode 103A to be charged to a negative charge is selected from a large number of direction control electrodes 103A and sequentially switched. For example, one direction control electrode 103A charged to a negative charge is sequentially switched to the direction control electrode 103A adjacent to the direction control electrode 103A. In this case, the other electrode 103A is charged to a positive charge. Thus, the in-plane position of the direction control electrode 103A charged to a negative charge with respect to the surface 13A of the substrate 13 is changed.

  In the apparatus 100, a high electric field is formed between the nozzle tip 101A and the direction control electrode 103A. For example, the resin solution 10 charged to a positive charge has a negative charge from the direction control electrode 103A charged to a negative charge. Electrical attraction works. In this case, at the tip of the nozzle tip 101A, the resin solution 10 takes the form of a cone-shaped Taylor cone whose surface is charged with a positive charge. For example, when the repulsive force of the charge exceeds the surface tension in the Taylor cone, the resin solution 10 is continuously released therefrom. In the released resin solution 10, the solvent of the resin solution 10 evaporates before reaching the surface 13 </ b> A of the base material 13, and the resin fibers 12 are spun on the surface 13 </ b> A of the base material 13.

  Here, in the present embodiment, the moving direction of the resin solution 10 is controlled by changing the in-plane position of the direction control electrode 103A charged to a negative charge with respect to the surface 13A of the base material 13. It is possible to control the arrival position of the resin fiber 12 on the 13 surfaces 13A.

  Specifically, in discharging the resin solution 10, one directional control electrode 103 </ b> A that is charged to a negative charge is controlled in the X direction by the control by the drive circuit, for example, as indicated by an arrow in FIG. Direction, positive direction of Y direction, negative direction of X direction, positive direction of Y direction, positive direction of X direction, and so on at a predetermined speed. In this case, the other direction control electrode 103A is charged to a positive charge. When scanning is performed on a predetermined region of the back surface 13B of the base material 13 in this way, for example, a large number of resin fibers 12 are formed on the front surface 13A along the scanning line by the direction control electrode 103A charged to a negative charge. Is done.

  By appropriately setting the scanning direction and various conditions of the direction control electrode 103A to be charged to a negative charge, a porous sheet having a single fiber layer oriented in a predetermined direction can be formed, of course. A porous sheet in which a plurality of fiber layers intersecting each other is laminated can be formed. For example, in the porous sheet 11 shown in FIG. 3, the fiber layer which consists of the resin fiber 12B whose orientation direction is X direction, and the fiber layer which consists of the resin fiber 12A whose orientation direction is Y direction are laminated | stacked alternately. The resin fibers are nanofibers having a fiber diameter of, for example, 30 to 5000 nm (preferably 200 nm), and the inter-fiber distance l is, for example, 0.5 to 20 μm. Moreover, when laminating | stacking a fiber layer as shown in FIG. 3, it is suitable to set the crossing angle of the orientation direction of resin fiber 12A, 12B in the range of 30-90 degrees, for example. In this aspect, when applied to the electrode layer of the fuel cell electrode, the gas can reach the catalyst more efficiently.

  As described above, in this embodiment, by controlling the moving direction of the resin solution 10, the arrival position of the resin fiber 12 on the surface 13 </ b> A of the base material 13 can be controlled. Can be controlled. Therefore, since the resin fibers 12 can be regularly arranged, the pore diameter between the resin fibers 12 can be made uniform, and the gas diffusion path can be shortened. As a result, when applied to the catalyst layer of a fuel cell electrode, for example, the fuel gas can reach the catalyst sufficiently efficiently.

  In particular, by setting the switching speed of the direction control electrode 103A charged to a negative charge to be equal to or higher than the arrival speed of the resin fibers 12 on the surface 13A of the base material 13, the resin fibers 12 are placed at predetermined positions on the surface 13A. It can be smoothly arranged in a straight line without being deposited.

  As mentioned above, although this invention was demonstrated using the said embodiment, this invention is not limited to the said embodiment, A various change is possible. For example, as a method of changing the in-plane position of the charged direction control electrode 103A with respect to the surface 13A of the substrate 13, the collector 103 is composed of a number of direction control electrodes 103A, and the direction control electrode 103A charged to a negative charge is used. Instead of the method of sequentially changing, for example, a method may be used in which the collector part is constituted by one direction control electrode, for example, and the direction control electrode is charged with a negative charge and moved. Specifically, for example, the porous sheet similar to the above-described embodiment is obtained by moving the direction control electrode 113A shown in FIG. 2 on the back surface 13B side of the base material 13 in the direction of the arrow in the drawing using a drive mechanism or the like. Can be manufactured.

  In the above embodiment, scanning is performed with dot-like electrodes using one direction control electrode as the direction control electrode 103A to be charged to a negative charge. However, the present invention is not limited to this. Deformation is possible. For example, scanning may be performed using a plurality of direction control electrodes 103A arranged in a line in the X direction or the Y direction as the direction control electrode 103A charged to a negative charge. In another example shown in FIG. 2, instead of the form shown in the figure, the direction control electrode 113A may be moved using a line extending in the X direction or the Y direction. .

  Furthermore, a plurality of nozzle layers having different resin solutions may be provided, and a plurality of fiber layers made of different resin fibers may be stacked by discharging the resin solution and controlling the direction of each nozzle 101. A plurality of nozzles 101 may be provided corresponding to each region of the surface 13 </ b> A of the base material 13, and the movement direction of the resin solution may be controlled by the direction control electrode corresponding to the nozzle 101 for each region of the base material 13.

  DESCRIPTION OF SYMBOLS 10 ... Resin solution, 11 ... Porous sheet, 12, 12A, 12B ... Resin fiber (fiber), 13 ... Base material, 13A ... Surface (one surface), 13B ... Back surface (other surface), 101 ... Nozzle, 101A ... Nozzle Tip portion, 102... Fixing portion, 102A, 102B... Fixing member, 103.

Claims (5)

Using a nozzle that discharges a resin solution toward one surface of the substrate, and one or more directional control collectors provided on the other surface opposite to the one surface of the substrate,
The resin solution is charged to a positive or negative charge, at least one of the direction control collectors is charged to a charge different from the resin solution, and the charged resin solution is transferred from the nozzle to the one surface of the substrate. By discharging toward the surface, to form a porous sheet made of resin fibers on one side of the substrate,
In the discharge of the charged resin solution, the moving direction of the resin solution is changed by changing the in-plane position of the direction control collector charged to a different charge from the resin solution with respect to one surface of the substrate. controls,
The in-plane position of the direction control collector charged to the different charge is changed by selecting and sequentially switching the direction control collector to be charged to the different charge from the two or more direction control collectors. A method for producing a porous sheet. The different charge switching speed of the directional control collector for charging into a porous sheet manufacturing method according to claim 1, characterized in that set to at least reach the speed of the fiber of the resin to one surface of the substrate.   The porous sheet manufacturing method according to claim 1, wherein the in-plane position of the direction control collector charged to the different charge is changed by moving the direction control collector charged to the different charge. Method. Produced by the production method of the porous sheet according to any one of claims 1 to 3 porous sheet fibers of the resin is characterized by comprising a fibrous layer that is oriented in a predetermined direction. The porous sheet according to claim 4 , wherein the porous sheet is applied to an electrode for a fuel cell.

Images