KR20060097806A - Porous nano-fiber and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a porous nanofiber and a method for manufacturing the same, the porous nanofiber of the present invention is 60 ~ 4,000nm in diameter and in the porous nanofibers in which fine pores are formed in the fiber, the depth of the fine pores Is 10 to 50 nm, and the width ratio (width / length) of the fine pores to the length of the fine pores is 0.15 to 0.85.

In the method of manufacturing the porous nanofiber according to the present invention, the spinning solution 1 in which the polymer resin is dissolved in a volatile solvent is electrospun on the collector 8 through the nozzle 2 under high voltage, and has a thickness of 60 to 4,000 nm. In preparing the phosphor nanofibers, the collector 8 is heated to a temperature range that is equal to or higher than the boiling point of the volatile solvent constituting the spinning solution and is equal to or lower than the secondary glass transition temperature (Tg) of the polymer resin.

Porous nanofibers of the present invention are formed in a number of slit-shaped pores (slit) that do not penetrate the nanofibers are useful as a material for various separation filters, gene carriers, enzyme carriers, catalysts, artificial leather, etc. .

     Porous, Indirect Heating, Nanofiber, Electrospinning, Collector, Nonwoven, Solvent, Volatility, Heating

Description

Porous nano-fiber and method of manufacturing the same

1 is an enlarged schematic view of a portion of the heating device 6 and the support 7 of the indirect heating method of the collector 8 used in the present invention.

2 is a process schematic of the present invention in a top-down electrospinning form;

Figure 3 is a process schematic of the present invention in the form of a bottom-up electrospinning.

Figure 4 is a process schematic diagram of the present invention in the form of a horizontal electrospinning.

5 is an enlarged photo of poly (L-lactide) nanofibers prepared in Example 1. FIG.

Figure 6 is an enlarged photo of the polystyrene (PS) nanofibers prepared in Example 2.

Figure 7 is an enlarged photo of the poly (L-lactide) nanofibers prepared in Comparative Example 1.

8 is an enlarged photo of polystyrene (PS) nanofibers prepared in Comparative Example 2. FIG.

* Explanation of symbols on the main parts of the drawings

1: spinning solution that is a polymer resin solution 2: nozzle

3: electrospun nanofibers 4: high voltage generator

5 conductive plate 6 heating device

7: support 8: collector (nano fiber integrated plate)

6a: circulation type heat source device 6b: fruit circulation tube

6c: fruit supply part 6d: fruit discharge part

The present invention relates to a porous nanofibers and a method of manufacturing the same, and more particularly, a plurality of fine pores in the form of slits that do not penetrate the nanofibers are formed, which is useful as various separation filters or gene / drug carriers. It relates to a nanofiber and a method for producing the same.

In the present invention, the nanofiber means a fiber having a thickness of 60 to 4,000 nm.

Non-woven fabrics, membranes, braids, etc. composed of nanofibers are widely used in household goods, agriculture, clothing, industrial, and the like. Specifically, it is used in various fields such as artificial leather, artificial suede, sanitary napkins, garments, diapers, packaging materials, miscellaneous materials, various filter materials, medical materials for gene carriers, defense materials such as bulletproof vests.

Conventional electrospinning apparatus described in US 4,044,404 and the like is a spinning liquid main tank for storing the spinning liquid, a metering pump for quantitative supply of the spinning liquid, a nozzle block arranged with a plurality of nozzles for discharging the spinning liquid, the nozzle bottom It consists of a voltage generator for generating a voltage and a collector to accumulate the fibers to be emitted.

Looking specifically at the electrospinning method using the electrospinning apparatus, the spinning liquid in the spinning liquid main tank is continuously metered into a plurality of nozzles to which a high voltage is applied through a metering pump.

Subsequently, the spinning liquid supplied to the nozzles spins through the nozzle onto a collector under high voltage to collect the nanofibers on the collector.

When manufacturing nanofibers by the conventional conventional electrospinning method as described above, there is a problem in that the nanofibers collected on the collet are dissolved by the solvent remaining on the collector, and thus the fiber forming ability is greatly reduced.

In particular, in the case of using a solvent having a low volatility (a solvent having a high boiling point), the above problem occurs more seriously.

In addition, even in the case of using a highly volatile solvent (low boiling point solvent), if the electrospinning for a long time for mass production of nanofibers, the solvent remains on the collector, thereby dissolving the nanofibers collected on the collector The above problem has arisen.

On the other hand, as a prior art for producing porous nanofibers by the electrospinning method, US Patent No. 6,790,528 discloses dissolving a polymer resin in a volatile solvent when preparing a spinning solution, and then electrospinning it onto a collector using a conventional electrospinning method. And a method for producing porous nanofibers by volatilizing a volatile solvent remaining in the spun nanofibers.

However, the method has a problem in that the use of volatile solvents causes the nanofibers accumulated on the collector to be dissolved by a volatile solvent that has not yet volatilized, thereby degrading the fiber formability. In other words, the above method has a problem that the fiber formability is lowered because there is no means for allowing the volatile solvent to evaporate rapidly on the collector.

In addition, the conventional method is because the pores formed on the nanofibers are in the form of a channel (Chenel) connected to the fiber center or penetrates the fiber, so the depth of the pores is too deep to provide excellent thermal insulation and lightness, but the mechanical properties of the nanofibers There was a problem of deterioration in physical properties.

In addition, since the porous nanofibers do not effectively collect drug / genes to be delivered into the nanofibers because the micropores are connected or penetrated to the center of the fiber, their transfer performance is also reduced.

 When the porous nanofibers are prepared by electrospinning using a volatile solvent, the present invention provides a form of fine pores formed in the nanofibers by heating the collector 8 in which the electrospun nanofibers are accumulated to an appropriate temperature. It is possible to control the width and to provide a method for preparing porous nanofibers that can greatly improve fiber formability.

In addition, in the present invention, since the fine pores formed on the nanofibers have a slit shape having a suitable depth, the nanoporous nanoparticles have excellent thermal properties, light weight, drug / gene transfer performance, filtering performance, and the like, and also have good mechanical properties. To provide a fiber.

Porous nanofibers of the present invention for achieving the above object, in the porous nanofibers having a diameter of 60 ~ 4,000nm and the pores are formed in the fiber, the depth of the micropores is 10 ~ 50nm, The width ratio (width / length) of the micropores to the length of the micropores is characterized in that 0.15 ~ 0.85.

In addition, in the method of manufacturing the porous nanofiber according to the present invention, the spinning solution 1 in which the polymer resin is dissolved in a volatile solvent is electrospun on the collector 8 through the nozzle 2 under high voltage to have a thickness of 10. In manufacturing a nanofiber of ˜4,000 nm, the collector 8 is heated to a temperature range that is equal to or higher than the boiling point of the volatile solvent constituting the spinning solution and is equal to or lower than the secondary glass transition temperature (Tg) of the polymer resin. .

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

First, when the spinning solution 1 in which the polymer resin is dissolved in the volatile solvent in the present invention is electrospun on the collector 8 through the nozzle 2 under high voltage, the boiling point of the volatile solvent ~ polymer By heating the temperature range below the secondary glass transition temperature (Tg) of the resin and rapidly evaporating the volatile solvent remaining on the collector, fine pores formed on the nanofibers are properly adjusted in shape (width / length ratio) and depth. And simultaneously prevent the electrospun nanofibers from dissolving again by the volatile solvent on the collector.

When the collector 8 is heated to below the boiling point of the volatile solvent in the spinning solution, the volatile solvent remaining on the collector does not evaporate quickly, and micropores do not form on the nanofibers to a sufficient level, and the spun nanofibers Dissolved again in the volatile solvent remaining on the collector causes a problem that the fiber forming ability is lowered.

On the other hand, when the collector 8 is heated to a temperature higher than the secondary glass transition temperature (Tg) of the polymer resin in the spinning solution, the solidification of the polymer resin is insufficient, the fluidity of the polymer is increased, and the formation of fine pores is rather reduced. A problem arises.

For example, when looking at the heating temperature of the collector 8, in the case of electrospinning the spinning solution dissolved in a poly (L-lactide) resin (Tg: 63 ℃) in dichloromethane (boiling point: 40 ℃) solvent ( The heating temperature of 8) is made into 40 to 63 degreeC.

As another example, when electrospinning a spinning solution in which polystyrene resin (Tg: 100 ° C) is dissolved in a tetrahydrofuran (boiling point: 66 ° C) solvent, the heating temperature of the collector 8 is 66 to 100 ° C, more preferably. It is good to set it as 66 degreeC level.

1 is an enlarged schematic view of a part of a heating apparatus 6 and a support 7 in one example of the collector used in the present invention.

In the present invention, it is preferable to use the collector 8 with the heating device 6 to promote volatilization of the solvent remaining on the collector when electrospinning the nanofibers.

As a specific example of the collector 8 provided with the said heating apparatus 6, (i) the support body 7 which is a lower end surface, (ii) the conductive plate 5 which is an upper end surface, and (iii) the said support body and a conductive plate The laminated body of the 3-layered structure comprised by the heating apparatus 6 located in between can be used.

As the heating device 6, as shown in FIG. 1, heating wires 6b coated with non-conductive polymers are arranged at regular intervals, and a heating plate 6a having a temperature controller 6c attached thereto may be used.

At this time, it is preferable to use silicon or the like which is excellent in current flow blocking property as the non-conductive polymer covering the hot wire.

Silicon is easy to handle due to its flexibility as well as its ability to block current flow.

The conductive plate 5 laminated on the heating device 6 may be made of a material having excellent conductivity, such as aluminum, copper, stainless steel, and the like.

On the other hand, the support 7 located below the heating device 6 is preferably a non-conductive material such as plastic, which is preferable for minimizing heat loss and increasing heat insulation effect.

FIG. 2 is a process schematic diagram of the invention for producing nanofibers in a top-down electrospinning form using a collector 8 with a heating device 6, FIG. 3 is a collector 8 with a heating device 6. Process schematic diagram of the present invention for producing nanofibers in a bottom-up electrospinning form using, Figure 4 is a pattern for producing nanofibers in a horizontal electrospinning form using a collector (8) having a heating device (6) Process schematic of the invention.

As shown in Figures 2 to 4 the present invention is applicable to both top-down electrospinning, bottom-up electrospinning and horizontal electrospinning.

The collector shown in FIG. 1 supplies heat to the heating wire 6b in the heating apparatus 6 during electrospinning to heat the heating plate 6a, and heat generated from the heating plate 6a forms the surface of the collector 8. It conducts to the conductive plate 5 to quickly volatilize the solvent remaining on the collector 8.

In addition, the surface temperature of the collector 8 can be controlled by the temperature controller 6c connected to the heating plate 6a.

As described above, in the present invention, when electrospinning the spinning solution containing the volatile solvent, the collector 8 is heated to above the boiling point of the volatile solvent to below the secondary glass transition temperature (Tg) of the polymer resin (8). The volatile solvent remaining in the c) phase can be evaporated at an appropriate rate.

As a result, the formability (width / length ratio) and depth of the micropores formed on the nanofibers can be appropriately adjusted while improving the fiber formability during electrospinning.

The porous nanofiber of the present invention has a diameter of 60 to 4,000 nm, and in the porous nanofibers in which fine pores are formed in the fiber, the depth of the micropores is 10 to 50 nm and the micropores of the length of the micropores. The width ratio of (width / length) is characterized in that 0.15 ~ 0.85.

In the present invention, the depth of the micropores, that is, the depth in which the micropores are dug in the direction perpendicular to the fiber axis is 20 to 50 nm.

In the porous nanofibers of the present invention, the width ratio (width / length ratio) of the micropores to the micropore length is 0.15 to 0.85.

Here, the length of the micropores means the size of the micropores in a direction parallel to the axial direction of the nanofibers, the width of the micropores means the size of the micropores in the direction perpendicular to the axial direction of the nanofibers.

If the ratio is out of the above range, lightness, warmth, drug / gene delivery performance, and the like are deteriorated.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited only to the following Examples.

Example 1

A spinning solution was prepared by dissolving a poly (L-lactide) resin (product of Boehringer Ingelheim) having a weight average molecular weight of 650,000 in dichloromethane to 3.5 wt%, and then preparing the spinning solution in the bottom-up electrospinning manner as shown in FIG. Electrospinning produced a porous nanofiber.

In the electrospinning, the voltage was 15 kV, the radiation distance was 15 cm, and the voltage generator was used by Simco's Model CH 50, and the nozzle plate was a nozzle with uniformly arranged 2,000 holes (nozzles) of 0.8 mm in diameter. Plates were used.

As the collector 8, (i) the support plates 7 of the polypropylene plate and (ii) the heating wires 6b coated with silicon are wired at regular intervals and the heating plate 6a to which the temperature controller 6c is attached. The surface temperature of the collector to 40 ° C. using a laminate having a three-layer structure consisting of a heater 6 positioned on the support and an aluminum film consisting of a conductive plate 5 positioned on the heater. It was.

An enlarged photograph of the porous nanofibers prepared as described above is shown in FIG. 5.

Example 2

25 wt% of a polystyrene resin (product of Aldrich CO.) Having a number average molecular weight of 140,000 was dissolved in tetrahydrofuran (THF) to prepare a spinning solution, and the prepared spinning solution was then transferred in a bottom-up electrospinning manner as shown in FIG. Spinning produced nanofibers.

In the electrospinning, the voltage was 15 kV, the radiation distance was 15 cm, and the voltage generator was used by Simco's Model CH 50, and the nozzle plate was a nozzle with uniformly arranged 2,000 holes (nozzles) of 0.8 mm in diameter. Plates were used.

As the collector 8, (i) the support plates 7 of the polypropylene plate and (ii) the heating wires 6b coated with silicon are wired at regular intervals and the heating plate 6a to which the temperature controller 6c is attached. The surface temperature of the collector to 66 ° C. using a laminate having a three-layer structure consisting of a heating device 6 and an aluminum film positioned on the support and consisting of a conductive plate 5 located on the heating device. It was.

An enlarged photograph of the porous nanofibers prepared as described above is shown in FIG. 6.

Comparative Example 1

Instead of using the collector 8 of Embodiment 1 with a heating device 6, the same as that of Embodiment 1 except that the collector was not heated using a conventional collector without the heating device 6 attached thereto. Porous nanofibers were prepared by the process and method.

An enlarged photograph of the prepared porous nanofibers is shown in FIG. 7.

Comparative Example 2

Porous nanofibers were manufactured by the same process and method as Example 2, except that the heating temperature of the collector 8 was changed to 100 °.

An enlarged photograph of the prepared porous nanofibers is shown in FIG. 8.

The results of measuring the depth and width / length ratio of the micropores formed on the porous nanofibers prepared in Examples 1, 2, Comparative Example 1 and Comparative Example 2 are shown in Table 1, respectively.

division Depth of Micropores (nm) Width / length ratio of micropores Micropore Formation Degree Example 1 30 0.40 Lots of formation Example 2 35 0.48 Lots of formation Comparative Example 1 5 0.20 Less shaping Comparative Example 2 12 0.90 Less shaping

The degree of formation of micropores in the table was compared with the porous nanofibers of FIG. 7 prepared in Example 1 and the porous nanofibers of FIG. 7 prepared in Comparative Example 1, and also of FIG. The porous fibers of FIG. 8 prepared in Comparative Example 2 were compared with the porous nanofibers.

Porous nanofibers of the present invention have good thermal insulation, drug delivery performance, filtering performance and mechanical strength due to the formation of slit-like micropores having a suitable depth.

Therefore, the porous fiber of the present invention is useful as a material for various separation filters, gene / drug carriers, enzyme carriers, catalysts, artificial leather, and the like.

Claims (8)

The spinning solution (1) in which the polymer resin is dissolved in a volatile solvent is electrospun on the collector (8) through the nozzle (2) under a high voltage to produce a nanofiber having a thickness of 60 to 4,000 nm. Method for producing a porous nanofiber, characterized in that for heating the collector (8) to a temperature range that is above the boiling point of the volatile solvent and less than the secondary glass transition temperature (Tg) of the polymer resin. 2. The collector 8 according to claim 1, wherein the collector 8 with the heating device 6 is (i) a lower surface of the support 7, (ii) a conductive plate 5 of the upper surface and (iii) between the support and the conductive plate. Method for producing a porous nanofiber, characterized in that the laminate of three-layer structure consisting of a heating device (6) located in the. The porous nanostructure according to claim 1 or 2, characterized in that the heating device (6) is a heating plate (6a) in which heating wires (6b) coated with a non-conductive polymer are wired at regular intervals and to which a temperature controller (6c) is attached. Method of making fibers. The method according to claim 2, wherein the conductive plate (5) is made of aluminum, copper or stainless steel. The method for producing porous nanofibers according to claim 2, wherein the material of the support (7) is a non-conductive plastic. The method of claim 3, wherein the nonconductive polymer is silicon. The method of claim 1, wherein the electrospinning type is a top-down electrospinning type, a bottom-up electrospinning type, or a horizontal electrospinning type. In a porous nanofiber having a diameter of 60 to 4,000 nm and micropores formed in the fiber, the depth of the micropores is 10 to 50 nm, and the width ratio (width / length) of the micropores to the length of the micropores. ) Is 0.15 ~ 0.85 porous nanofibers, characterized in that.

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