JP2007303021A - Density gradient type nonwoven fabric and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonwoven fabric which is formed from only one kind of superfine fibers, has high fiber density portions and low fiber density portions, has regular fiber density gradients, and is suitable for cell cultures and the like, and to provide a method for producing such the nonwoven fabric. <P>SOLUTION: This method for producing the density gradient type nonwoven fabric comprises a preparation process for preparing a spinning solution prepared by dissolving an organic polymerizing substance in an organic solvent, and an electrostatic spraying process for rotating a cylindrical accumulation conductor having grid type openings, applying a high voltage to the spinning solution to electrostatically spray the spinning solution on the earthed accumulation conductor, and forming the electrostatically spun organic fibers as the nonwoven fabric on the outer surface of the accumulation conductor, wherein the nonwoven fabric has grid-like high density portions and web-like low density portions surrounded with the high density portions. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a non-woven fabric composed of organic fibers suitable for cell culture and the like, and to a density gradient nonwoven fabric having two density portions, a high-density portion and a web-like low-density portion, and a method for producing the same.

  Nonwoven fabrics using extra fine fibers are mainly used as an air intake filter for automobiles. Various density gradient nonwoven fabrics are used as means for extending the filter life while maintaining a high cleaning effect.

  For example, Patent Document 1 discloses a density gradient for a filter in which two or more tanks are laminated so that the average denier is large to small, needle punching is performed from the thin fiber layer side, and constituent fibers are entangled with each other. A mold nonwoven fabric is disclosed.

  Patent Document 2 discloses a spunbonded nonwoven fabric in which the outer layer is treated with water repellency, the intermediate layer is a fiber layer made of hydrophobic fibers and hydrophilic fibers, and the inner layer is made of hydrophobic fibers, hydrophilic fibers, and heat. The three-layer structure fiber laminate, which is a fiber layer composed of fusible fibers, is integrated by performing physical entanglement processing from the inner layer toward the outer layer, and the entire three-layer structure fiber laminate is resin. A thin filter is disclosed which is formed into a density gradient type by bonding and further performing waveform processing.

  Patent Document 3 discloses a filter structure in which fibers having fine fineness below a specific value are reinforced with a mesh sheet of a frame body.

  Further, Patent Document 4 discloses a method for producing a nonwoven fabric in which a nonwoven fabric is prepared using sea-island-structured split fibers, and then subjected to split processing to be dispersed as ultrafine fibers.

  Further, Patent Document 5 and Patent Document 6 disclose a method of manufacturing a cloth in which a knitted fabric or a woven fabric is produced with divided fibers and then divided, thereby giving directionality to the ultrafine fibers.

  Non-patent literature 1 and non-patent literature 2 disclose general web-like processed products using synthetic resin as a raw material and a method for producing the same.

  On the other hand, in the field of cell culture, a cell support may be required for growing cultured cells, and a collagen porous gel is used for culturing skin cells and the like.

Here, in cell culture, it is also important to give appropriate stimulation to the cells. However, when a polymer film or gel is used as a support for the cultured cells, the cultured cells are supported by the “surface”. Will not give enough stimulation to the cells.
Japanese Patent Laid-Open No. 10-180023 JP 2003-210921 A Japanese Patent Laid-Open No. 11-179121 Japanese Patent Laid-Open No. 9-302563 JP 2000-265343 A JP 2000-342501 A http://www.daikin.co.jp/chm/pro/fluoro/polyflonweb/ http://www.asahi-kasei.co.jp/eltas/seizo.htm

  When using non-woven fabrics composed of ultrafine fibers in cell culture as a support for cultured cells, if the fibers are dense, cells will only be placed on the uneven surface of the non-woven fabric, but if the fiber density is lowered, the depth direction It is considered that it would be ideal if there is a non-woven fabric partially having a low fiber density while maintaining strength.

  However, since the nonwoven fabric currently disclosed by patent document 1 or patent document 2 needs to laminate | stack the fiber layer of a different fiber diameter, a manufacturing process is complicated. Further, the fiber density can be controlled only in the thickness direction.

  Further, the filter disclosed in Patent Document 3 is made of polyester and uses a binder, so that it has a problem that it is not suitable for cell culture.

  Furthermore, in the nonwoven fabric disclosed in Patent Document 4, it is possible to leave the regularity (direction) of the fibers before division to some extent even after the division treatment, but to give the nonwoven fabric a high degree of regularity. I can't. The cloth manufacturing methods disclosed in Patent Document 5 and Patent Document 6 also cannot be an ideal density gradient nonwoven fabric manufacturing method for cell culture because directionality is limited in the knitting method and weaving method. .

  The present invention consists of only one type of ultrafine fiber, has a high fiber density portion and a low fiber density portion, and is suitable for cell culture etc. in which the fiber density is regularly gradient, and the production of such a nonwoven fabric The purpose is to provide a method.

  The present invention applies a high voltage to a spinning solution made of an organic polymerizable substance, and electrostatically sprays it on an electric conductor for integration having a plurality of openings on the surface, thereby producing ultrafine fibers having a diameter of 0.1 to 20 μm or less. The present invention relates to a method for producing a density gradient nonwoven fabric having a portion having a high fiber density and a web-like portion having a low fiber density.

Specifically, the present invention
A preparation step of preparing a spinning solution in which an organic polymerizable substance is dissolved in an organic solvent;
While rotating a cylindrical accumulating conductor having a plurality of openings, a high voltage is applied to the spinning solution and electrostatic spraying is performed toward the accumulating conductor, thereby producing an electrospun organic fiber. Including an electrostatic spraying step formed as a non-woven fabric on the outer surface of the electric conductor for integration,
The non-woven fabric has a high-density portion and a web-shaped low-density portion surrounded by the high-density portion.

The present invention also provides:
A non-woven fabric composed of organic fibers obtained by electrostatic spinning of an organic polymerizable material,
With high density parts,
The present invention relates to a density gradient nonwoven fabric having a web-like low-density portion surrounded by a high-density portion (Claim 6).

  The organic polymerizable substance is preferably a biodegradable organic substance such as polycaprolactone, a hydroxyalkanoate homopolymer or copolymer, collagen, or a lactic acid / glycolic acid copolymer (claims 2 and 7). This is because if the electrospun organic fiber is biodegradable, it is not necessary to remove the nonwoven fabric later in cell culture or the like.

  Hydroxyalkanoate homopolymers include poly (3-hydroxybutyrate), poly (4-hydroxybutyrate), poly (3-hydroxyvalerate), poly (3-hydroxyhexanoate), poly (3 -Hydroxyoctanoate), poly (3-hydroxyoctadecanoate) and the like. Among these, poly (3-hydroxybutyrate) is preferable.

  The hydroxyalkanoate copolymer is preferably a 3-hydroxybutyrate / 3-hydroxyhexanoate copolymer.

  The applied voltage to the spinning solution is preferably 5 kV or more and 40 kV or less (Claim 3).

  The thickness of the high density portion of the nonwoven fabric is preferably 0.1 mm or more and 2 mm or less (claims 4 and 8). This is because when the thickness is less than 0.1 mm, the strength as a non-woven fabric is insufficient, while when it exceeds 2 mm, it is difficult to obtain a density gradient effect.

  The fiber diameter of the nonwoven fabric is preferably 0.1 μm or more and 20 μm or less (Claims 5 and 9). If the thickness is less than 0.1 μm, the strength as a non-woven fabric will be insufficient. On the other hand, if the thickness exceeds 20 μm, the effect as a density gradient material cannot be obtained.

  Although the density gradient nonwoven fabric of the present invention is composed of one kind of ultrafine fiber, the high density portion and the low density portion are regularly controlled, and the density is reduced by the lattice-like high density portion. It has an unconventional form in which the density portion is surrounded. Moreover, since it has a grid-like high-density part, there is also mechanical strength and the fiber diameter is very uniform.

  The cell culture part and the space holding part are the same, and have a small mesh size and a low-density part that are impossible with a fabric, making it suitable for three-dimensional cell culture.

  In addition, the density gradient nonwoven fabric manufacturing method of the present invention combines the electrostatic spraying method with a specially shaped integration conductor, so that the fiberization and the density gradient can be performed by one simple manufacturing process. Nonwoven fabrics can be manufactured. There is no need for a “weaving” or “knitting” process or a “fusion” process for the fibers.

  Furthermore, the shape of the mesh structure can be controlled by the shape of the conductors for integration, and the fibers are deposited rather than crossed to form a nonwoven fabric, so that unevenness due to the thickness of the fibers cannot be achieved.

  Embodiments of the present invention will be described below with reference to the drawings as appropriate. The present invention is not limited to these.

  An example of the electrostatic spraying apparatus used in the manufacturing method of the density gradient type nonwoven fabric of this invention is shown in FIG. The electrostatic spraying device 1 includes an insulating plate 3 on the top of the sealed container 2. A metal nozzle 5 connected to a metal holder 4 is fixed to the insulating plate 3. A liquid feed pipe 7 is connected to the metal holder 4 on the opposite side of the metal nozzle 5, and a high voltage power source 6 is connected to the metal holder 4.

  The liquid feeding pipe 7 leads to a container 9 accommodated in another sealed container 8, and the container 9 is filled with an organic solvent solution of biodegradable organic polymerizable fibers as a spinning liquid 10. Yes. Furthermore, the sealed container 8 is connected to the compressor 11 so that the inside can be in a pressurized state.

  When the compressor 11 is turned ON, the inside of the sealed container 8 is pressurized, and the spinning liquid 10 in the container 9 is fed to the metal nozzle 3 through the liquid feeding pipe 7.

  An accumulation conductor 12 is installed inside the sealed container 2. Conductive struts 17 are inserted into the inner holes of the integration conductor 12. An earth 14 is installed on the support column 17.

  Moreover, the support | pillar 17 is connected to the motor 13 and can be rotated centering | focusing on a center axis | shaft by starting the motor 13. FIG.

  A cover 16 is installed on the top of the motor 13 in order to prevent the electrostatically sprayed organic polymerizable fibers from adhering to the motor 13.

  Next, the integration conductor 12 will be described with reference to FIG. The integration conductor 12 is made of, for example, a conductive material such as metal or carbon fiber as shown in FIG. 2A, and a conductive plate 21 having a plurality of openings is shown in FIG. 2B. It is in a state of being rounded into a cylindrical shape. The conductive plate 21 includes a lattice portion 22 and an opening portion 23, and the opening portion 23 and the inner hole 24 communicate with each other after being formed as the integration conductor 12.

  In FIG. 2, the opening shape of the conductive plate 21 and the integration conductor is an example of a square. However, the shape is not limited to this and may be a rectangle, a circle, an ellipse, a polygon, a parallelogram, or the like. However, if the area of the opening is too large, organic fibers will not accumulate in the opening even if the spinning solution is electrostatically sprayed. For this reason, when the shape of the opening is a square, the length of one side is preferably 20 mm or less.

  On the other hand, if the area of the opening is too small, when the spinning solution is electrostatically sprayed, organic fibers are accumulated in the same way in the lattice part and the opening, and thus a density gradient nonwoven fabric cannot be produced. For this reason, when the shape of the opening is a square, the length of one side is preferably 0.25 mm or more.

  The integration conductor 12 is fixed by inserting a support column 17 into the inner hole 24 and sandwiching it between two rubber rings 18 attached to the support column 17.

  Here, when the high voltage power supply 6 is turned on, a high voltage is applied to the metal nozzle 5 through the metal holder 4. At this time, as shown in FIG. 3, charges are induced and accumulated in the spinning solution 10 flowing in the metal nozzle 5 by a high voltage. After being ejected from the metal nozzle 5, the spinning liquids 10 repel each other in order to be positively charged.

  This repulsive force opposes the surface tension of the spinning liquid, and when the charge criticality is exceeded (when the surface tension is exceeded), the spinning liquid becomes charged mist. Since the surface area of the charged mist is very large with respect to the volume, the organic solvent is efficiently evaporated, and the charge density is increased due to the decrease in the volume, so that the spinning solution is split into the charged fine mist 15.

  Although the metal nozzle 5 is applied with a high voltage, the conductive support column 17 and the integration conductor 12 fixed to the support column 17 are grounded. Therefore, the metal nozzle 5 and the integration conductor 12 A strong electric field is formed between them. The charged micro mist 15 proceeds toward the integration conductor 12 by the formed electric field while repelling each other, but the solvent is volatilized on the way, and the fiber is made into an organic polymerizable fiber on the integration conductor 12. To be collected. At this time, a charge having a sign opposite to the charge applied to the metal nozzle 5 may be applied to the integration conductor 12.

  The inner diameter of the metal nozzle 5 is preferably 0.1 mm or more and 2.0 mm or less, and more preferably 0.1 mm or more and 1.0 mm or less.

  The high voltage applied to the metal holder 4 (and the metal nozzle 5) is preferably a DC voltage of 5 kV to 40 kV, more preferably a DC voltage of 15 kV to 30 kV.

  The discharge rate of the spinning liquid from the metal nozzle 5 is preferably 0.01 mL / min or more and 10 mL / min or less. This discharge speed can be adjusted by controlling the output of the compressor 11 that pressurizes the inside of the sealed container 8.

  Further, the extrusion pressure of the spinning solution from the metal nozzle 5 is preferably 0.01 MPa / min to 2 MPa, and more preferably 0.01 MPa / min to 0.5 MPa. This extrusion pressure can also be adjusted by controlling the output of the compressor 11 that pressurizes the inside of the sealed container 8.

  Here, the holder and the nozzle are made of metal. However, the holder and the nozzle are not limited to metal and may be made of a conductive material. Further, the spinning solution may be electrostatically sprayed in an open system without using the sealed container 2.

  Further, the accumulation conductor 12 and the metal nozzle 5 may be arranged horizontally and electrostatic spraying may be performed from the horizontal direction.

  Organic fibers refined by electrostatic spraying and charged with a positive or negative charge are attracted to the accumulation conductor 12 provided with the earth 14 and accumulated as a non-woven fabric. In the method, the grid portion 22 and the opening portion 23 are provided in the integration conductor 12, thereby giving a gradient to the force attracted by the ground and controlling the fiber density of the organic fibers 25 to be integrated. Is possible.

  That is, as shown in FIG. 4, when the lattice portion 22 and the opening portion 23 of the conductor for accumulation 12 are compared, the lattice portion 22 has a stronger electrical attraction force, and therefore the organic fiber 25 has the lattice portion 22. It accumulates more on the top and becomes a high density part (part with high fiber density). On the other hand, since the organic fibers 25 are not easily accumulated in the opening 23, a low density portion (a portion having a low fiber density) is formed.

  Further, by rotating the accumulation conductor 12, it is possible to manufacture a density gradient type nonwoven fabric having a uniform fiber diameter and dispersion state.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not limited only to these Examples.

[Example 1]
As Example 1 of the present invention, 3-hydroxybutyrate / 3-hydroxyhexanoate copolymer (hereinafter referred to as PHBH), which is a kind of hydroxyalkanoate homopolymer or copolymer, was produced by the following production method. A density gradient nonwoven fabric composed of fibers was produced.

1) Preparation Step First, PHBH (average molecular weight 772,000, 3-hydroxybutyrate: 3-hydroxyhexanoate = 93.9: 6.1 (molar ratio), manufactured by Kaneka Corporation) was dissolved in dichloromethane and filtered. A PHBH dichloromethane solution (PHBH concentration: 10% by weight) was obtained. The PHBH concentration is preferably 5% by weight or more and 15% by weight or less.

2) Electrostatic spraying step Next, the PHBH dichloromethane solution produced in the above preparation step was made into fibers using the electrostatic spraying device 1 shown in FIG. 1 and accumulated as PHBH fibers on the surface of the accumulation conductor 12. Here, a stainless steel nozzle having an inner diameter of 0.32 mm and a length of 1 cm was used as the metal nozzle 5, and the distance from the lower end of the metal nozzle 5 to the collecting conductor 12 was 10 cm. Further, a variable voltage device (high voltage power supply 6: manufactured by Pulse Electronics Technology Co., Ltd.) was connected to a stainless steel holder (metal holder 4), and a DC voltage of 15 kV was applied. The extrusion pressure of the PHBH dichloromethane solution was 0.02 MPa.

  As the integration conductor 12, a 150 mesh stainless steel net (2 cm × 3 cm rectangle, material SUS304, stainless steel wire diameter 0.05 mm) formed in a cylindrical shape was used. A stainless steel column having a diameter of 6 mm was used as the support column 17, and the integration conductor 12 and the support column 17 were fixed using two rubber rings 18 as shown in FIG. 1.

  The column 17 was rotated 2625 by the motor 13 per minute. In addition, it is preferable to rotate the support | pillar 17 200-3000 rotations per minute.

  As a result of electrostatic spraying of the spinning solution while rotating the conductor for accumulation 12, most of the PHBH fibers were accumulated in the lattice portion 22 of the conductor for accumulation 12, and the fibers on the lattice portion 22 became dense. . On the other hand, PHBH fibers did not accumulate much in the openings 23, and the fibers in the openings 23 had a low density.

  After electrostatic spraying for about 10 minutes, the integration conductor 12 with PHBH fibers accumulated on the outer surface was removed from the support column 17, and a cut with a cutter knife was made along the long axis of the integration conductor 12. Then, the density gradient type non-woven fabric having a substantially rectangular lattice-like high density portion and a web-like low density portion surrounded by the high density portion was removed from the outer surface of the integration conductor 12. A partially enlarged photograph is shown in FIG.

  As a result of taking an electron micrograph, the density gradient nonwoven fabric of Example 1 had an average fiber diameter of about 5 μm and a small variation in fiber diameter. The fiber surface was also very smooth. Further, the shape of the density gradient nonwoven fabric as a whole was substantially the same as the stainless steel mesh forming the accumulation conductor 12.

[Example 2]
Next, as Example 2, a solution in which polycaprolactone (hereinafter referred to as PCL) (average molecular weight 70 to 100,000) was dissolved in dichloromethane to a concentration of 10% by weight was used as the spinning solution. The PCL concentration is preferably 8% by weight or more and 20% by weight or less, and more preferably 10% by weight or more and 14% by weight or less.

  As the integration conductor 12, a stainless steel plate (material SUS304) having a grid portion width of 0.1 mm, an opening portion side of 0.5 mm, and a thickness of 0.1 mm formed into a cylindrical shape having an inner diameter of 1 cm and a length of 2 cm is used. did. Except that, a density gradient nonwoven fabric was produced in the same manner as in Example 1.

  6 (a) to 6 (d) are enlarged views of a part of the density gradient type nonwoven fabric of this example produced when the electrostatic spraying time is 5 minutes, 10 minutes, 15 minutes and 20 minutes, respectively. It is a photograph. As is clear from these figures, it was possible to control the density and thickness of the low density portion of the web by adjusting the electrostatic spraying time.

  The density-gradient nonwoven fabric of Example 2 (thickness of the high density portion: about 1.2 mm) was photographed with an electron microscope. As a result, the average fiber diameter was about 5 μm, and the fiber diameter variation was small. The fiber surface was also very smooth. Further, the shape of the density gradient nonwoven fabric as a whole was substantially the same as the stainless steel mesh forming the accumulation conductor 12.

  In addition, the density gradient type nonwoven fabric of Example 2 was flat compared to Example 1 in the grid portion of the used accumulation conductor 12, so that the shape of the high density portion was higher than that of the density gradient type nonwoven fabric of Example 1. Was also flat. The mechanical strength was also superior to the density gradient nonwoven fabric of Example 1.

[Example 3]
Next, as Example 3, a lactic acid / glycolic acid copolymer (hereinafter referred to as PLGA) (average molecular weight 220,000, lactic acid: glycolic acid = 75: 25 (molar ratio)) was dissolved in dichloromethane to obtain 15% by weight. The solution obtained was used as the spinning solution. The PCL concentration is preferably 10% by weight or more and 30% by weight or less, and more preferably 12% by weight or more and 20% by weight or less.

  The same integration conductor 12 as that of Example 2 was used. A density gradient nonwoven fabric was produced in the same manner as in Example 2 except that a DC voltage of 20 kV was applied and the extrusion pressure of the PLGA dichloromethane solution was 0.05 MPa (electrostatic spraying time of about 10 minutes). In addition, the photograph which expanded a part of density gradient type nonwoven fabric of Example 3 is shown in FIG.

  As a result of taking an electron micrograph, the density gradient nonwoven fabric of Example 3 had an average fiber diameter of about 5 μm and a small variation in fiber diameter. The fiber surface was also very smooth. Further, the shape of the density gradient nonwoven fabric as a whole was substantially the same as the stainless steel mesh forming the accumulation conductor 12.

[Example 4]
Next, as Example 4, a solution containing collagen was used as a spinning solution. First, soluble collagen was dissolved in hydrochloric acid adjusted to pH 2 and then filtered to obtain an aqueous collagen solution. Next, hexafluoroisopropanol (HFIP) was added at a rate of 20% by weight to the collagen aqueous solution to obtain a collagen solution (collagen concentration in the 20% by weight HFIP solution was 6.5% by weight).

  The weight ratio of water and HFIP in the collagen solution is preferably 8: 2 to 5: 5, and the collagen content in the collagen solution is preferably 5% by weight to 10% by weight.

  Collagen aqueous solution has high viscosity, and collagen fibers cannot be produced by electrostatic spraying as it is, but by adding HFIP, it is possible to produce collagen fibers by electrostatic spraying with reduced viscosity. It became.

  As the integration conductor 12, a 20 mesh stainless steel net (2 cm × 3 cm rectangle, material SUS304, stainless steel wire diameter 0.2 mm) formed in a cylindrical shape was used. A density gradient nonwoven fabric was produced in the same manner as in Example 1 except that a DC voltage of 25 kV was applied and the extrusion pressure of the collagen solution was 0.1 MPa. In addition, the photograph which expanded a part of density gradient type nonwoven fabric of Example 4 is shown in FIG.

  As a result of taking an electron micrograph, the density gradient nonwoven fabric of Example 4 had an average fiber diameter of about 5 μm, and there was little variation in the fiber diameter. The fiber surface was also very smooth. Further, the shape of the density gradient nonwoven fabric as a whole was substantially the same as the stainless steel mesh forming the accumulation conductor 12.

  In Example 2, the density gradient nonwoven fabric is formed in the range where one side of the opening (in the case of a square) of the integrating conductor 12 is not less than 0.25 mm and not more than 20 mm, but one side of the opening is 20 mm. When it exceeded, the tendency which becomes a string-like nonwoven fabric as shown in FIG. 9 was recognized. On the other hand, when one side of the opening was less than 0.25 mm, the high density portion and the low density portion could not be distinguished, and a tendency to become a normal nonwoven fabric was recognized. Such a phenomenon was confirmed in common with Example 1, Example 3, and Example 4.

  The density gradient nonwoven fabric and the method for producing the same of the present invention are useful not only in biological fields such as cell culture, but also in a wide range of industrial fields such as chemistry and machinery using a nonwoven fabric filter.

It is the schematic which shows an example of the electrostatic spray apparatus used in the manufacturing method of the collagen fiber of this invention. It is a figure explaining an example of the conductor for integration, FIG. 2 (a) is a grid | lattice-like electroconductive board, FIG.2 (b) is an external view of the conductor for integration which formed it. It is an enlarged schematic diagram which shows the state of the spinning liquid near a metal nozzle lower end part when operating an electrostatic spraying apparatus. It is a conceptual diagram explaining the fiber integration | stacking body to the conductor for integration | stacking in the manufacturing method of the density gradient type nonwoven fabric of this invention. 2 is an enlarged photograph of a part of the density gradient nonwoven fabric of Example 1. It is the photograph which expanded a part of density gradient type nonwoven fabric of Example 2, FIG.6 (a) is 5 minutes, FIG.6 (b) is 10 minutes, FIG.6 (c) is 15 minutes, FIG.6 (d). Is a density gradient nonwoven fabric when sprayed for 20 minutes. It is the photograph which expanded a part of density gradient type nonwoven fabric of Example 3. FIG. It is the photograph which expanded a part of density gradient type nonwoven fabric of Example 4. FIG. It is the photograph which expanded a part of string-like nonwoven fabric formed on the same conditions as Example 2 when one side of the opening part of the conductor for integration is 25 mm.

Explanation of symbols

1: Electrostatic spraying device 2: Sealed container 3: Insulating plate 4: Metal holder 5: Metal nozzle 6: High-pressure power supply 7: Liquid supply pipe 8: Another sealed container 9: Container 10: Spinning liquid 11: Compressor 12 : Conductor for integration 13: Motor 14: Ground 15: Charged micro mist 16: Cover 17: Strut 18: Rubber ring 21: Conductive plate 22: Grid part 23: Opening part 24: Inner hole 25: Organic fiber

Claims (9)

A preparation step of preparing a spinning solution in which an organic polymerizable substance is dissolved in an organic solvent;
While rotating a cylindrical accumulating conductor having a plurality of openings, a high voltage is applied to the spinning solution and electrostatic spraying is performed toward the accumulating conductor that is grounded. An electrostatic spraying step of forming a spun organic fiber as a non-woven fabric on the outer surface of the conductor for accumulation,
The said nonwoven fabric has a high density part and the web-shaped low density part enclosed by the high density part, The manufacturing method of the density gradient type nonwoven fabric characterized by the above-mentioned.   The method for producing a density gradient nonwoven fabric according to claim 1, wherein the organic polymerizable substance is a polycaprolactone, a hydroxyalkanoate homopolymer or copolymer, collagen or a lactic acid / glycolic acid copolymer.   The method for producing a density gradient nonwoven fabric according to claim 1 or 2, wherein a voltage applied to the spinning liquid is 5 kV or more and 40 kV or less.   The method for producing a density gradient nonwoven fabric according to any one of claims 1 to 3, wherein a thickness of the high density portion of the nonwoven fabric is 0.1 mm or more and 2 mm or less.   The method for producing a density gradient nonwoven fabric according to any one of claims 1 to 4, wherein an average fiber diameter of the nonwoven fabric is 0.1 µm or more and 20 µm or less. A non-woven fabric composed of organic fibers obtained by electrostatic spinning of an organic polymerizable material,
With high density parts,
A density gradient nonwoven fabric having a web-like low density portion surrounded by a high density portion.   The density gradient nonwoven fabric according to claim 6, wherein the organic polymerizable substance is polycaprolactone, 3-hydroxybutyric acid / 3-hydroxyhexanoic acid copolymer, collagen, or lactic acid / glycolic acid copolymer.   The density gradient nonwoven fabric according to claim 6 or 7, wherein a thickness of the high density portion of the nonwoven fabric is 0.1 mm or more and 2 mm or less. The density gradient nonwoven fabric according to any one of claims 6 to 8, wherein an average fiber diameter is 0.1 µm or more and 20 µm or less.