JP2007211370A - Method for producing laminate sheet of microfiber and laminate sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminate sheet formed with a microfiber layer on a substrate, which has high adhesion to the substrate and is excellent in air-permeability, and to provide a method for producing the sheet. <P>SOLUTION: The method for producing a laminate sheet comprises laminating a microfiber layer by electrostatic spraying of a microfiber material solution obtained by liquifying the microfiber component using a solvent, wherein the method comprises a step for forming an intermediate layer 3 which is composed of a first fiber diameter of the microfiber on the resin-based substrate 2 by the first electrostatic spraying, and a step for forming a surface layer 4 which is composed of microfibers comprising a second fiber diameter less than the first fiber diameter on the intermediate layer 3 by the second electrostatic spraying. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a laminated sheet in which fiber layers such as various filters and catalyst support materials are formed, and a laminated sheet produced using the production method.

A conventional laminated sheet on which a fine fiber layer is formed includes, for example, a structure in which a sheet made of fine fibers is melt bonded to a substrate by thermocompression bonding. (For example, refer to Patent Document 1). Also, there is a method in which ultrasonic vibration is applied to a sheet made of fine fibers and a part of the base material, and is melted and adhered by frictional heat.
Japanese Patent Laid-Open No. 08-244127 Japanese Patent Laid-Open No. 07-207563

  In general, the sheet described in Patent Document 1 is obtained by softening or melting a part of a sheet by applying heat and pressure to two sheets with a heated roll, and fusing the sheets together. It is. Therefore, in the fused area, there is a problem that fibers are melted to form a film and air permeability is lowered. Further, in the method described in Patent Document 2, since the surfaces of the areas to be thermally fused are fused to each other by frictional heat, the entire sheet at the fused portion changes into a film shape and causes clogging. Compared to the above, the degree of air permeability deterioration can be suppressed, but the problem of air permeability deterioration still remains. Moreover, in order to obtain adhesiveness, in either method of Patent Documents 1 and 2, it is necessary to increase the fusion area, or more firmly, and the air permeability and the adhesiveness in the laminated sheet are It was a conflicting request.

  The present invention solves the conventional problems, and relates to a laminated sheet composed of a fine fiber layer and a base material, and provides a method for producing a laminated sheet that hardly deteriorates air permeability and provides high adhesion. The purpose is to do.

In order to solve the conventional problems, the method for producing a laminated sheet according to the present invention includes a fine fiber layer obtained by electrostatically spraying a fine fiber material solution in which a component of fine fibers is liquefied using a solvent on a resin sheet. In the manufacturing method of the lamination sheet which laminates,
Forming an intermediate layer composed of a first fiber diameter of the fine fibers on a resin-based substrate by a first electrostatic spray; and a second smaller than the first fiber diameter on the intermediate layer. And a step of forming a surface layer of fine fibers having a fiber diameter by second electrostatic spraying subsequent to the first electrostatic spraying, and has good air permeability and adhesion. Excellent laminated sheet can be realized.

Moreover, the laminated sheet of the present invention is a laminated sheet in which fine fiber layers are laminated by electrostatic spraying a fine fiber substance solution in which components of fine fibers are liquefied using a solvent,
A resin-based substrate, an intermediate layer made of the fine fibers having a first fiber diameter formed by first electrostatic spraying on the resin-based substrate, and the first layer on the intermediate layer And a surface layer of fine fibers having a second fiber diameter smaller than the first fiber diameter, which is laminated by the second electrostatic spraying following the electrostatic spraying.

  According to the method of the present invention, it is possible to form a fine fiber layer having high adhesion to a substrate and excellent air permeability on the substrate.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, with regard to a method for producing a laminated sheet of the present invention and a laminated sheet produced using the production method.

  FIG. 1 is a view showing the structure of a laminated sheet in Example 1 of the present invention.

  In FIG. 1, 1 is a fine fiber layer. The material of the fine fiber layer 1 is polyurethane. 2 is a base material and the material is a fluororesin. The fine fiber layer 1 is composed of an intermediate layer 3 and a surface layer 4. FIG. 2 shows a manufacturing process of the laminated sheet having the structure shown in FIG. FIG. 3 shows an electrostatic spraying device used for producing a laminated sheet. A method for manufacturing the laminated sheet shown in FIG. 1 will be described with reference to FIGS.

  First, the intermediate layer 3 is formed on the substrate surface 5 in the intermediate layer forming step 7. In this intermediate layer forming step 7, polyurethane is applied onto the substrate surface 5 by electrostatic spraying using the electrostatic spraying device shown in FIG.

  In the apparatus shown in FIG. 3, 9 is a capillary. In the capillary, a material which is a constituent component of the fine fiber layer is put in a solution state. In this example, a polyurethane solution dissolved in toluene and dimethylformamide was used. Reference numeral 2 denotes a base material which is disposed below the capillary 9. Reference numeral 10 denotes a high voltage power source, and the negative electrode 11 of the high voltage power source 10 is connected to the base material holder 16. The positive electrode 12 of the high voltage power supply 10 is connected to an electrode line 13 inserted into the capillary 9. The high voltage power supply 10 is configured to generate a potential difference between the capillary 9 and the substrate 2. A control device 14 is connected to the high voltage power supply 10 and controls the voltage generated by the high voltage power supply 10. In the intermediate layer forming step 7, the high voltage power source 10 generates a voltage of 9 kV, and the intermediate layer 3 is formed with the distance 15 from the base material 2 to the tip of the capillary 9 being 100 mm.

  The intermediate layer 3 is made of polyurethane fibers in the same manner as the surface layer 4, but is formed so that the fiber diameter is larger than the fiber diameter of the surface layer 4. The reason for increasing the fiber diameter of the surface layer 4 will be described later. In this example, the diameter of the fiber was controlled by the distance 15 from the substrate 2 to the capillary 9. Specifically, when the distance 15 is increased, the fiber becomes finer, and when the distance 15 is decreased, the fiber becomes thicker. That is, an intermediate layer is formed on the substrate 2 by the first electrostatic spraying, and then the distance 15 is set on the formed intermediate layer to be larger than that during the first electrostatic spraying, so that the second electrostatic A surface layer is formed by spraying. By such two-stage electrostatic spraying, a surface layer having a small fiber diameter can be formed on an intermediate layer having a large fiber diameter. The inventors consider the reason why this phenomenon occurs as follows.

  In the first embodiment, when a high voltage is applied between the capillary 9 and the substrate 2 by the high voltage power supply 10, the capillary 9 is positively charged. Since the tip of the capillary 9 has a sharp shape with a diameter of about 100 μm to 1 mm, concentration of electric charges occurs, and a positively charged polyurethane droplet is sprayed into the air by an electric repulsion action. . The sprayed polyurethane droplets fly toward and adhere to the grounded substrate 2. During flight, the charge amount of the droplet hardly changes, but since the volume of the droplet becomes small due to drying, the electric repulsive force inside the droplet increases, and one droplet becomes a plurality of small droplets. Split. When the droplets become small due to the splitting, the ratio of the surface area to the volume increases, so that drying further proceeds. Due to the effect that the drying of the droplets causes breakup and further drying proceeds, the polyurethane droplets become smaller.

  Since the polyurethane fibers adhering to the base material 2 are obtained by drying the polyurethane droplets, the smaller the fibers are divided, the smaller the fibers are formed. When the distance 15 from the capillary 9 to the substrate 2 is increased, a long time for drying and splitting is lengthened, and fine fibers are formed. When the distance 15 is small, the time for drying and splitting is shortened. Is believed to be formed. Moreover, if the distance 15 from the capillary 9 to the base material 2 is reduced and the polyurethane fiber that is not sufficiently dried is attached to the base material 2, the polyurethane fiber is attached to the base material surface 5 at the moment of attachment. Since it is still in a solution state and has fluidity, it adheres along the irregularities of the substrate surface 5 and is dried, so that high adhesion can be obtained. On the other hand, when the distance 15 is increased, the polyurethane droplets adhere to the substrate 2 in a dry state, have no fluidity, and do not adhere along the unevenness of the substrate surface 5, thereby obtaining high adhesion. It is considered impossible.

  That is, in order to improve the adhesion between the fine fiber layer 1 and the substrate 2 in electrostatic spraying, the intermediate layer is formed by applying polyurethane droplets that are not completely dried to the substrate 2. 3 is effective. In particular, if the diameter of the fibers in the intermediate layer 3 is larger than the diameter of the fibers constituting the fine fiber layer 1, the surface layer 4 is formed on the substrate 2. Compared with the case of forming directly on the substrate 2, a solution-like polyurethane droplet which is not dried at the time of forming the intermediate layer 3 is applied onto the substrate 2, and high adhesion can be obtained.

  Next, in the fine fiber layer forming step 8, the surface layer 4 is formed on the base material 2 on which the intermediate layer 3 is formed. The surface layer 4 was formed using the apparatus shown in FIG. 3 in the same manner as the intermediate layer 3 was formed.

  In the surface layer forming step 8, a voltage of 20 kV was generated by the high voltage power source 10 and the distance 15 from the substrate 2 to the tip of the capillary 9 was set to 200 mm. Regarding the adhesion between the surface layer 4 and the intermediate layer 3, since the intermediate layer 3 and the surface layer 4 are the same material, it is known that high adhesion can be obtained without using special conditions. In the formation of the intermediate layer 3, if a fiber thicker than the fibers in the surface layer 4 is formed, high adhesion between the fine fiber layer 1 and the substrate 2 can be obtained.

  The laminated sheet produced as described above was evaluated for adhesion between the fine fiber layer 1 and the substrate 2. The evaluation was performed by the method shown in FIG. In FIG. 4, 2 is a base material, 1 is a fine fiber layer, and the fine fiber layer 1 is composed of an intermediate layer 3 and a surface layer 4. After folding this laminated sheet along the fold line 13, the width of the part where the fine fiber layer 1 was peeled from the substrate 2 on the fold line 13 was observed to evaluate the adhesion.

  In this example, the case where the peeled portion was 10% or less was marked with ◯, the case where the peeled portion was 10% to 50% was indicated by Δ, and the case where the peeled portion was 50% or more was marked with ×. The results are shown in FIG. As a result, it was confirmed that the adhesion was improved as compared with the case where the intermediate layer was not formed. Further, since the laminated sheet itself is a soft fiber, it is easily broken and it is difficult to measure the absolute value of the peel strength.

  In order to evaluate the air permeability, when the fine fiber layer is observed with an electron microscope and an optical microscope to check for clogging, there is almost no clogging as compared with the sheets prepared by the methods of Patent Documents 1 and 2. It can be confirmed that the air permeability is greatly improved. FIG. 5A schematically shows the result of observation of the fiber layer after formation of the intermediate layer 3 with a microscope. In addition, in order to further improve the adhesion, the fiber diameter of the intermediate layer 3 is increased, and as a result of examination, when the fiber diameter exceeds approximately 10 μm, the fiber becomes thicker as shown in FIG. Along with this, the node 21 of the fiber in which a large number of fibers are gathered becomes large, so that it can be confirmed that clogging occurs, and the fiber diameter is preferably 10 μm or less.

  In addition, when the intermediate layer 3 was formed with a fiber diameter of 0.3 μm or less during the formation of the intermediate layer 3, the adhesion was hardly improved. This is considered to be because the fibers are almost completely dried when fibers of 0.3 μm or less are formed. Therefore, it is desirable to form the intermediate layer 3 with fibers having a fiber diameter of between 0.3 μm and 10 μm.

  In the present example, the thickness of the intermediate layer 3 was set to about 5 μm to 30 μm. Since the thicker the intermediate layer 3 is, the longer it takes to form, so the productivity is deteriorated. However, when the thickness is equal to or less than the fiber diameter of the intermediate layer 3, the fine fiber layer 1 and the substrate 2 are in direct contact with each other. Therefore, it leads to a decrease in adhesion.

  In addition to the manufacturing method described above, as a method for improving the adhesion between the base material 2 and the intermediate layer 3, it is effective to use a material containing the same material as the intermediate layer 3 for the base material 2. For example, by using a material in which polyurethane is woven into a fluororesin base material as the base material 2, the adhesiveness with less clogging as shown in FIG. 5A is improved and a good laminated sheet is obtained. In this method, when the intermediate layer 3 is initially formed, the polyurethane in the base material 2 is dissolved on the surface 5 of the base material 2 and dried in a state of being mixed with the polyurethane fibers constituting the intermediate layer 3. Adhesion can be obtained.

  As another method for improving the adhesion, in the above embodiment, the surface 5 of the base material 2 is a flat surface with small irregularities compared to the fiber diameter, but the same as the fiber diameter of the intermediate layer 3. By roughening the surface 5 of the substrate 2 until the size of the irregularities on the surface of the substrate 2 increases, the fibers forming the intermediate layer 3 can easily enter the irregularities of the intermediate layer 3, and the size of the irregularities Compared to the case where it is small, the fiber deeply enters the concave portion of the concave and convex portions, so that it is considered that the anchor effect works and the adhesion is improved.

  In order to improve mass productivity, it is effective to continuously form the intermediate layer 3 and the fine fiber layer 1. In this case, it is important to clean the air containing the solution generated as the intermediate layer 3 and the fine fiber layer 1 are dried. If the air containing the solution is left as it is, the drying does not proceed during the formation of the intermediate layer 3 and the fine fiber layer 1, the fragmentation of the sprayed droplets is suppressed, and the fiber diameter becomes thicker than the control target. There is also the possibility of clogging. Therefore, in order to continuously form the intermediate layer 3 and the fine fiber layer 1 at high speed and improve mass productivity, it is important to clean the air containing the solution generated around the product in the manufacturing process.

  Air purification can be performed by forcibly blowing air with a blower fan or exhausting the air around the product with an exhaust pump, and increasing the ambient temperature around the product to promote evaporation of the solution. Since the drying of the droplets can be promoted by this, it is effective for forming a high-speed fine fiber layer.

  In this embodiment, polyurethane is used as a material, but the method of this embodiment is also effectively applied to the case where a fine fiber layer of polyethylene glycol is laminated. In addition, fine fiber layers such as polyethylene oxide, polyvinyl alcohol, polyacrylic acid, and polyvinyl chloride can be formed.

  Moreover, about the base material, although the case where the fluororesin was used was described in the present embodiment, the present invention is not limited to the type of the base material. For example, polyester, nylon, polyethylene, acrylic, vinyl chloride, The present invention can also be effectively applied when a resin material such as polypropylene or polyurethane is used as the base material. Even when other resins are used, the method of the present invention can be effectively applied as long as the adhesion mechanism between the intermediate layer and the substrate of the present invention is established.

  A product and a manufacturing method using ultrafine fibers according to the present invention are a laminated sheet having a high adhesion to a base material and having a fine fiber layer excellent in air permeability and a manufacturing method thereof. It is useful as a substrate on which a fiber layer such as a catalyst support material is formed.

Structure diagram of laminated sheet in Example 1 of the present invention The figure for demonstrating the preparation procedure of the lamination sheet in Example 1 of this invention The figure which shows the apparatus which produces the lamination sheet in Example 1 of this invention The figure for demonstrating evaluation of the adhesiveness of the fine fiber layer and base material of a lamination sheet in Example 1 of this invention The figure for demonstrating typically the fiber structure of the intermediate | middle layer of the lamination sheet in Example 1 of this invention The figure for demonstrating the evaluation result of the adhesiveness of the lamination sheet in Example 1 of this invention Structural diagram of a laminated sheet with a conventional fine fiber layer

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fine fiber layer 2 Base material 3 Intermediate | middle layer 4 Surface layer 5 Base material surface 6 Preparatory process 7 Intermediate layer formation process 8 Surface layer formation process 9 Capillary 10 High voltage power supply 11 Negative pole 12 Positive pole 13 Electrode line 14 Control apparatus 15 Base Distance from material 2 to tip of capillary 9 16 Base material holder 17 Apparatus outer wall 18 Capillary holder 1
19 Capillary holder 2
20 Holder fixing part 21 Microscope 22 Fiber node 23 Conventional fine fiber layer 24 Base material

Claims (9)

In the method for producing a laminated sheet in which the fine fiber material solution in which the constituents of the fine fiber are liquefied using a solvent is electrostatically sprayed on the resin sheet to laminate the fine fiber layer,
Forming an intermediate layer comprising the first fiber diameter of the fine fibers on a resin-based substrate by first electrostatic spraying;
Forming a surface layer of fine fibers having a second fiber diameter smaller than the first fiber diameter on the intermediate layer by a second electrostatic spray following the first electrostatic spray;
The manufacturing method of the lamination sheet characterized by having. The distance between the sprayed position of the charged droplets of the fine fiber material solution and the resin-based substrate is such that the first electrostatic spray is smaller than the second electrostatic spray. The manufacturing method of the lamination sheet of Claim 1 to do. The method for producing a laminated sheet according to claim 1, wherein the intermediate layer is formed of fibers having a fiber diameter of 0.3 µm to 10 µm, and the intermediate layer has a thickness of 5 µm to 30 µm. The method for producing a laminated sheet according to claim 3, wherein the surface of the resin base material is roughened to the same extent as the fiber diameter of the intermediate layer. The said fine fiber is a material of any one of polyurethane, polyethylene glycol, polyethylene oxide, polyvinyl alcohol, polyacrylic acid, and polyvinyl chloride, or a mixture of any of these. A method for producing a laminated sheet. A laminated sheet in which a fine fiber layer is laminated by electrostatic spraying a fine fiber substance solution in which a component of fine fiber is liquefied using a solvent,
A resin-based substrate;
An intermediate layer composed of the fine fibers having a first fiber diameter formed by first electrostatic spraying on the resin-based substrate;
A surface layer of fine fibers having a second fiber diameter smaller than the first fiber diameter laminated on the intermediate layer by the second electrostatic spray following the first electrostatic spray;
A laminated sheet comprising: The laminated sheet according to claim 6, wherein the intermediate layer is formed of fibers having a fiber diameter of 0.3 μm to 10 μm, and the thickness of the intermediate layer is 5 μm to 30 μm. The laminated sheet according to claim 7, wherein the surface of the resin base material is roughened to the same extent as the fiber diameter of the intermediate layer. The said fine fiber is a material of any one of polyurethane, polyethylene glycol, polyethylene oxide, polyvinyl alcohol, polyacrylic acid, and polyvinyl chloride, or a mixture of any of these. Laminated sheet.

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