KR100835082B1 - Crosslinked polyvinyl alcohol nanofiber web and its preparation method using electrospinning - Google Patents

Abstract

The present invention relates to a water-soluble polyvinyl alcohol (PVA) nanofiber web using an electrospinning method, a nanofiber web including a method of controlling the degree of crosslinking of the nanofiber web and a method of imparting functionality to the nanofiber web by mixing and spinning a functional polymer. It relates to a manufacturing method of.

The crosslinked PVA nanofiber web according to the present invention can be used as a functional material such as mask pack material, wound dressing, artificial skin, drug delivery material and ion exchange membrane.

Electrospinning, nanofibers, crosslinking, polyvinyl alcohol, polyacrylic acid, polyethylene oxide

Description

Crosslinked polyvinyl alcohol nanofiber web using eletrospinning and process for preparing the same}

1 is an enlarged real picture of a PVA nanofiber web according to a first embodiment of the present invention.

2 is an enlarged real photograph of a PVA / PAA nanofiber web according to a second embodiment of the present invention.

3 is an enlarged real picture of a PVA / PEO nanofiber web according to a third embodiment of the present invention.

4 is an enlarged real picture of a PVA / PEO / PAA nanofiber web according to a fourth embodiment of the present invention.

5 is an enlarged real picture of a heat-treated PVA nanofiber web according to a fifth embodiment of the present invention.

6 is an enlarged real photograph of a heat treated PVA / PAA nanofiber web according to a sixth embodiment of the present invention.

7 is an enlarged real picture of a heat-treated PVA / PEO nanofiber web according to a seventh embodiment of the present invention.

8 is an enlarged real photograph of a PVA / PEO / PAA nanofiber web heat-treated according to an eighth embodiment of the present invention.

The present invention relates to a functional material that can be used as a mask pack material, wound dressing, artificial skin, drug delivery material and ion exchange membrane, and more specifically, a water-soluble polyvinyl alcohol nanofiber web and Nao fiber using an electrospinning method. The present invention relates to a method for controlling the degree of crosslinking of a web and a method for producing a nanofiber web including a method of imparting functionality to a nanofiber web by mixing and spinning a functional polymer.

The scientific basis of electrospinning for the production of nanofibers has been developed in 1882 by Raleigh's calculations that electrostatic forces can overcome surface tensions in liquid drops.

Electrospinning is stretched to have a cross-sectional area of tens to hundreds of nanometers as the polymer solution or polymer melt moves to the grounded integrated plate through the nozzle of the reservoir by the electrostatic force of high voltage of several kV or more Known as the technology. That is, when the externally applied electric field exceeds a certain threshold value, the charge generated at the surface of the polymer solution extruded from the nozzle is greater than the surface tension of the polymer solution, thereby generating a liquid jet. The microfiber generated in this way is stretched to the microfiber through the electrically generated bending instability. This process can control the thickness of the fiber by varying the size of the electric field and the concentration of the polymer solution.

Fibers produced by electrospinning have new properties when their diameters are reduced from micrometers to nanometers, such as increasing the ratio of surface area to volume, improving surface functionality, and improving mechanical properties including tension.

Nanofibers produced in this way are filter materials (EP1483034, US6,875,256), photochemical sensor materials, carbon materials such as carbon nanotubes (US2005 / 0025974, EP1500677), biomedical materials (US4,043,331, US4,878,908, WO 05/039664, WO 05/037339), tissue engineering materials (WO 05/026530, WO 05/047493), drug delivery materials (WO 04/014304), DNA manufacturing base materials and cosmetic materials (WO 01/026610), etc. The scope of application is wide.

In order for the nanofibers produced by the electrospinning method to be used for medical or cosmetic materials, the polymeric material of the material must be harmless to human skin. In addition, the solvent used to dissolve the high molecular material is rapidly evaporated during the electrospinning process so that little remains in the prepared nanofibers, it is more preferable to use a solvent that is harmless to the human body.

Polyvinyl alcohol (PVA), which may be selected as one of such polymer materials, is a biocompatible hydrophilic polymer material and may be used as a drug delivery system or membrane because of its excellent physical and mechanical properties and chemical resistance.

However, in spite of the excellent physical properties of the fiber made of PVA, it has been limited in the application of the material because of its high solubility in water. Attempts to solve these problems through physical and chemical treatments have been published in several research papers and patents, and the representative ones are physical crosslinking by heat treatment or crystallization and chemical crosslinking by adding a crosslinking agent.

Physical methods of preparing PVA hydrogels include: i) freezing of high concentration PVA aqueous solution, ii) partial lyophilization of aqueous PVA solution under vacuum, iii) repeating freezing and thawing of PVA aqueous solution, iv) crystallization at low temperature of aqueous PVA solution, v) irradiated with radiation after freezing and thawing PVA aqueous solution to prepare a hydrogel, vi) crystallization using alcohol, vii) thermal crosslinking, and the like.

As a chemical method for preparing a PVA hydrogel, there is a method of forming a gel using a monomolecular difunctional crosslinking agent such as boronic acid, dicarboxylic acid, glutaaldehyde, etc. (KR2004-19982, KR2005-94559, KR2005-112432, KR2006-9051).

Such a method provides a method for preparing PVA hydrogel on bulk polymer or film, but crosslinking method using monomolecular difunctional crosslinking agent has toxicity that is unsuitable for use in biological materials.

Accordingly, an object of the present invention is an efficient method for controlling the degree of discoloration of a nanofiber web according to the crosslinking degree and the crosslinking reaction of the PVA nanofiber web using polyacrylic acid (PAA) and polyethylene oxide; Through a method of imparting functionalities to the nanofiber web by mixing electrospun PEO), to provide a method for producing a nanofiber web insoluble in aqueous solution, excellent adhesion to the skin and impregnation of the active ingredient.

Another object of the present invention is to provide a nanofiber web manufactured according to the manufacturing method, which can be used as a mask sheet and wound dressing sheet for cosmetic purposes.

The present invention provides a nanofiber web consisting of nanofiber aggregates of polyvinyl alcohol, polyacrylic acid and polyethylene oxide in order to achieve the above object.

Nanofiber web of the present invention is a nanofiber aggregate is cross-linked to form a porous sheet in an insoluble hydrogel state, in particular, characterized in that the polyethylene oxide has a structure trapped in the three-dimensional network of polyvinyl alcohol.

In the present invention, the content of polyethylene oxide is preferably 1 to 50 parts by weight based on 100 parts by weight of polyvinyl alcohol, and the content of polyacrylic acid is preferably 5 to 50 parts by weight based on 100 parts by weight of polyvinyl alcohol.

Nanofiber web of the present invention can be usefully used as a functional material, such as mask pack material, wound dressing, artificial skin, drug delivery material or ion exchange membrane.

The present invention also provides a method for producing a nanofiber web comprising preparing a mixed solution of polyvinyl alcohol, polyacrylic acid and polyethylene oxide, and forming a nanofiber web by electrospinning the mixed solution.

The production method of the present invention is characterized in that the nanofiber web is processed in an insoluble hydrogel state using physical and chemical crosslinking methods, wherein the physical crosslinking method is preferably a heat treatment in an atmospheric pressure or a vacuum oven.

In addition, the production method of the present invention crosslinking degree by adjusting the content of polyacrylic acid 5 to 50 parts by weight with respect to 100 parts by weight of polyvinyl alcohol, heat treatment temperature 100 to 150 ℃, heat treatment time in the range of 5 minutes to 6 hours And controlling the degree of discoloration.

The present invention forms a fiber aggregate consisting of nanofiber microfibers by electrospinning polyvinyl alcohol, which is a water-soluble polymer, so that its properties are flexible, there are many micro spaces, and the surface area per unit weight has a feature of adhesion to skin. And it provides a nanofiber web excellent in impregnation amount and delivery of the active ingredient. In addition, the present invention provides an efficient method for crosslinking nano webs prepared using PAA, and an effective method for improving impregnation and skin adhesion using PEO as an additive.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The present invention relates to a method of crosslinking and imparting functionality of an electrospun PVA nanofiber web.

PVA nanofiber web manufacturing and crosslinking method according to the present invention is a) a method for crosslinking the electrospun PVA nanofiber web by heat treatment in a vacuum state, b) a polymer compound capable of forming a crosslink with the PVA nanofiber web Phosphorus PAA is crosslinked by heat treatment after mixed spinning, c) crosslinking of water-soluble polymer PEO by heat treatment after mixed spinning to give functionality to PVA nanofiber web, d) PAA, PEO on PVA nanofiber web There is a method of improving the crosslinking degree and impregnation by composite spinning.

The nanofiber web prepared by the present invention is prepared in the form of a porous sheet having a fiber diameter of 50 to 800 nm, but is dissolved again in the aqueous liquid unless the post-treatment process of the crosslinking reaction is involved. In addition, in order to immerse the active ingredient impregnated liquid in the prepared nanofiber web, an appropriate crosslinking degree should be maintained, thereby controlling the crosslinking degree using physical and chemical crosslinking methods.

In general, PVA has a high hydrophilic hydroxyl group, so that it has a high solubility in water, but induces a dehydration reaction through heat treatment in a vacuum state to form an insoluble hydrogel state by forming crosslinks. In particular, since the PVA sheet composed of nanofibers is porous, a three-dimensional network structure can be formed by a crosslinking reaction to increase the degree of swelling in water, and also increase the impregnation rate of the active ingredient.

The prepared PVA nanoweb is insoluble and highly swellable in the form of a sheet by annealing for 5 minutes to 6 hours at a heating temperature of 100 to 150 ° C. in a vacuum oven. Heat treatment is the easiest PVA crosslinking method, but there is a disadvantage that it is difficult to properly control the degree of crosslinking and discoloration of the nanoweb.

In order to more easily control the degree of crosslinking and to minimize discoloration due to heat treatment, PAA was mixed with the PVA spinning solution and spun. PAA is a representative hydrophilic polymer having a carboxyl group, which is an ionization functional group, in the polymer side chain, thereby forming an ester bond with the hydroxyl group of PVA.

By using PAA as the polymer crosslinking agent of PVA, the crosslinking reaction can be more easily progressed and the time taken for the crosslinking reaction can be reduced. The crosslinking reaction using PAA is possible at both atmospheric pressure and vacuum, and has the effect of suppressing the apparent color change, ie, yellowing, by heat treatment.

PVA nanofiber webs mixed with the PAA were spun in a transparent or white sheet form in aqueous solution. The degree of crosslinking of the PVA nanoweb is controlled according to the content ratio of PAA used during electrospinning, the heat treatment time, and the heat treatment temperature.

Since PVA nanofiber webs lose hydroxyl groups by heat treatment after electrospinning, they are lower than the hydrophilicity of pure PVA. High molecular weight PEO was mixed and spun to improve the impregnation performance of the crosslinked PVA nanofiber web. The hydrophilic polymer PEO is trapped in the three-dimensional network structure of the PVA by heat treatment, thereby improving the impregnation of the cross-linked PVA nanoweb.

Hereinafter, the manufacturing process and crosslinking method of the PVA nanofiber web according to the present invention will be described.

Method for producing a PVA nanofiber web according to the present invention comprises a) preparing a spinning solution, b) electrospinning step, c) heat treatment step.

First, a spinning solution is prepared. Four types of spinning solutions, namely 1) PVA, 2) PVA / PAA, 3) PVA / PEO, and 4) PVA / PAA / PEO can be used, and their preparation methods are as follows.

First, in the case of PVA spinning solution, PVA was added to ultrapure water and stirred at 90 to 105 ° C. to prepare a spinning solution having a concentration of 5 to 15 wt%.

Second, in the case of PVA / PAA spinning solution, 5 to 50 parts by weight of PAA is mixed with respect to 100 parts by weight of PVA to prepare a spinning solution.

Third, in the case of PVA / PEO spinning solution, the spinning solution is prepared by mixing 1 to 50 parts by weight of PEO with respect to 100 parts by weight of PVA.

Fourth, in the case of PVA / PAA / PEO spinning solution, to prepare a spinning solution by mixing 1 to 50 parts by weight of PEO to 100 parts by weight of PVA / PAA mixed solution prepared above.

The molecular weight of PVA used in the present invention is preferably 10 to 200 K, most preferably PVA having a molecular weight of 100 to 180 K and deacetylated at least 99%. The concentration of the PVA spinning solution is most preferably 5 to 15% by weight, in particular 6 to 7% by weight.

In the present invention, the molecular weight of the polymer cross-linked PAA is preferably 10 to 1,000 K, and particularly preferably PAA having a molecular weight of 100 to 300 K. The amount of PAA used in the spinning solution mixed with PVA is most preferably 5 to 50 parts by weight, particularly 5 to 15 parts by weight based on 100 parts by weight of PVA.

In addition, the molecular weight of the PEO used to improve the impregnation performance in the present invention is preferably 100 to 5,000 K, and particularly preferably PEO having a molecular weight of 1,000 to 2,000 K. The amount of PEO used in the spinning solution mixed with PVA is most preferably 1 to 50 parts by weight, in particular 2 to 7 parts by weight, based on 100 parts by weight of PVA.

Next, the spinning solution prepared as described above is discharged under a high voltage electric field to spin the nanofibers onto the integrated plate. In this case, the applied voltage is 10 to 30 kW, the discharge rate of the spinning solution is 0.1 to 3 ml / h, and the distance TCD from the tip of the spinneret to the integrated plate is preferably 10 to 50 cm.

Next, the nanofiber web prepared as described above is cut to a predetermined size and then heat-treated in vacuum or normal pressure.

Specifically, in the case of PVA, PVA / PEO nanofiber web, crosslinked by heat treatment for 5 minutes to 6 hours at a temperature of 100 to 150 ℃ in a vacuum oven, the most preferable heat treatment conditions are 110 to 120 ℃, 1 to 1.5 hours to be.

For PVA / PAA, PVA / PAA / PEO nanofiber webs, crosslinking is carried out by heat treatment for 5 minutes to 6 hours at a temperature of 100 to 150 ° C. in an atmospheric pressure or vacuum oven, and the most preferable heat treatment conditions are 110 to 120 ° C., 1 To 1.5 hours.

EXAMPLE

Hereinafter, the present invention will be described in detail by way of examples. These examples are merely illustrative of the present invention, and it will be apparent to those skilled in the art that the present invention is not limited to these examples.

Example  One: PVA  Nano Fiber

7 g of PVA was added to 93 g of distilled water, and stirred for about 3 hours at a temperature of 100 to 105 ° C. to prepare a 7 wt% solution. Using the electrospinning apparatus, the prepared PVA solution was set at a distance of 15 to 30 cm from the tip of the spinneret to an integrated plate and a voltage of 18 to 25 kV, and then electrospun while pushing at a speed of 0.5 to 1 ml / h. An assembly of nanofibers was prepared. The nozzle size used at this time was 32 gauge. An image analyzer was used to analyze the diameter of the ultrafine fibers constituting the fiber assembly. The fiber aggregates prepared above were magnified and observed at a rate of 5,000 times using a scanning microscope, and the results are shown in FIG. 1. As can be seen in Figure 1, the fiber aggregate had a structure in which nanofibers having a uniform thickness of 200 to 300 nm were entangled with each other in the form of a nonwoven fabric.

Example  2: PVA Of PAA  Nano Fiber

0.35 to 0.7 g of PAA was added to the 7 wt% PVA solution prepared in Example 1 to prepare a PVA / PAA mixed solution. The content of PAA relative to 100 parts by weight of PVA was 5 to 10 parts by weight. Using the electrospinning apparatus, the prepared PVA / PAA solution was set at a distance from the tip of the spinneret to an integrated plate of 15 to 30 cm and a voltage of 18 to 25 mV, while pushing at a rate of 0.5 to 1 ml / h. Spinning produced an aggregate of nanofibers. The nozzle size used at this time was 32 gauge. An image analyzer was used to analyze the diameter of the ultrafine fibers constituting the fiber assembly. The fiber aggregates prepared above were magnified and observed at a rate of 5,000 times using a scanning microscope, and the results are shown in FIG. 2. As can be seen in Figure 2, the fiber aggregate had a structure in which nanofibers having a uniform thickness of 200 to 500 nm were entangled with each other in the form of a nonwoven fabric.

Example  3: PVA Of PEO  Nano Fiber

A PVA / PEO mixed solution was prepared by adding 0.07 to 0.35 g of PEO to the 7 wt% PVA solution prepared in Example 1. The content of PEO relative to 100 parts by weight of PVA was 1 to 5 parts by weight. Using the electrospinning device, the distance from the tip of the spinneret to the integrated plate was set to 15 to 30 cm, and the voltage was set to 18 to 25 mV. Then, the electrospinning was carried out while pushing at a speed of 0.5 to 1 ml / h to mix PVA / PEO nano. A fiber assembly of fibers was prepared. The nozzle size used at this time was 32 gauge. An image analyzer was used to analyze the diameter of the ultrafine fibers constituting the fiber assembly. The fiber aggregates prepared above were magnified and observed at a rate of 10,000 times using a scanning microscope, and the results are shown in FIG. 3. As can be seen in Figure 3, the fiber aggregate had a structure in which nanofibers having a uniform thickness of 450 to 550 nm were entangled with each other in the form of a nonwoven fabric.

Example  4: PVA Of PAA Of PEO  Nano Fiber

0.35 to 0.7 g PAA and 0.07 to 0.35 g of PEO were added to the 7 wt% PVA solution prepared in Example 1 to prepare a PVA / PAA / PEO mixed solution. The content of PAA relative to 100 parts by weight of PVA was 5 to 10 parts by weight, and the content of PEO to 100 parts by weight of PVA was 1 to 5 parts by weight. Using the electrospinning device, the distance from the tip of the spinneret to the integrated plate is set to 15 to 30 cm, and the voltage is set to 18 to 25 mV, and then electrospun while pushing at a speed of 0.5 to 1 ml / h to PVA / PAA / PEO. A fiber assembly of mixed nanofibers was prepared. The nozzle size used at this time was 32 gauge. An image analyzer was used to analyze the diameter of the ultrafine fibers constituting the fiber assembly. The fiber aggregates prepared above were magnified and observed at a rate of 5,000 times using a scanning microscope, and the results are shown in FIG. 4. As shown in FIG. 4, the fiber aggregate had a structure in which nanofibers having a uniform thickness of 500 to 600 nm were entangled with each other in the form of a nonwoven fabric.

Example  5: PVA  Crosslinking by Heat Treatment of Nanofibers

The PVA nanofiber web prepared in Example 1 was cut to a constant size of 10 cm × 10 cm and then heat-treated for 5 minutes to 6 hours in a vacuum oven of 100 to 150 ℃. The heat-treated sample was magnified and observed at a rate of 5,000 times using a scanning microscope, and the results are shown in FIG. 5.

Example  6: PVA Of PAA  Crosslinking by Heat Treatment of Nanofibers

The PVA / PAA nanofiber web prepared in Example 2 was cut to a constant size of 10 cm × 10 cm and heat-treated for 5 minutes to 6 hours in an atmospheric pressure or vacuum oven at 100 to 150 ° C. The heat-treated sample was magnified and observed at a rate of 3,000 times using a scanning microscope, and the results are shown in FIG. 6.

Example  7: PVA Of PEO  Crosslinking by Heat Treatment of Nanofibers

The PVA / PEO nanofiber web prepared in Example 3 was cut to a constant size of 10 cm × 10 cm and then heat-treated in a vacuum oven at 100 to 150 ° C. for 5 minutes to 6 hours. The heat-treated sample was magnified and observed at a rate of 3,000 times using a scanning microscope, and the results are shown in FIG. 7.

Example  8: PVA Of PAA Of PEO  Crosslinking by Heat Treatment of Nanofibers

The PVA / PAA / PEO nanofiber web prepared in Example 4 was cut to a constant size of 10 cm × 10 cm and heat-treated for 5 minutes to 6 hours in an atmospheric pressure or vacuum oven at 100 to 150 ° C. The heat-treated sample was magnified and observed at a rate of 3,000 times using a scanning microscope, and the results are shown in FIG. 8.

[Test Example]

Test Example  1: whiteness measurement

In order to examine the effect of whiteness by PAA, the samples after crosslinking of Examples 5 to 8 were measured using a colorimeter respectively, and the results are shown in Table 1. The numerical values in Table 1 indicate yellowness among the color coordinate coordinate values. The closer to 0 the numerical value is, the higher the whiteness is. As a result of the measurement, as PAA is added, the value approaches 0, indicating that the whiteness increases.

Test Example  2: swelling measurement

In order to examine the water impregnation effect by PEO, the weight of the crosslinked samples of Examples 5 to 8 was measured. Then, the water was absorbed and then taken out in distilled water to remove the water on the surface and weighed again to determine the moisture content in the interior, the results are shown in Table 1. The moisture content for each sample is determined by the following equation.

Moisture Content (%) = gH2O / g Dry Sample = (Ws-Wd) / Wd

(Ws = weight of wet sample, Wd = weight of dried sample)

As can be seen in Table 1 it can be seen that the degree of swelling increases with the addition of PEO. In addition, the swelling degree of the sample (Example 8) spun and mixed with PAA and PEO simultaneously in PVA showed the best results. Therefore, it can be seen that the PVA / PAA / PEO nanofiber web of the present invention has improved skin adhesion by nanofibers and impregnation by swelling degree.

 Sample Whiteness Swelling degree (%) Example 5 2.20 565 Example 6 0.36 786 Example 7 2.01 929 Example 8 0.62 1192

The present invention forms a fiber aggregate composed of microfibers having a fiber diameter or nano size by electrospinning polyvinyl alcohol, which is a water-soluble polymer, so that the properties are flexible, there are many micro spaces, and the surface area per unit weight is large. It provides a nanofiber web with excellent adhesion and impregnation amount and effective delivery of active ingredients. In addition, the present invention provides an efficient method for crosslinking nano webs prepared using PAA, and an effective method for improving impregnation and skin adhesion using PEO as an additive.

Claims (10)

Nanofiber aggregates of polyvinyl alcohol, polyacrylic acid and polyethylene oxide, The nanofiber aggregate is crosslinked to form a porous sheet in an insoluble hydrogel state, Polyethylene oxide has a structure trapped in the three-dimensional network of polyvinyl alcohol, The content of polyethylene oxide is 1 to 50 parts by weight based on 100 parts by weight of polyvinyl alcohol, The content of polyacrylic acid is 5 to 50 parts by weight based on 100 parts by weight of polyvinyl alcohol, A nanofiber web characterized in that the molecular weight of polyvinyl alcohol is 10 to 200 K, the molecular weight of polyacrylic acid is 10 to 1,000 K, and the molecular weight of polyethylene oxide is 100 to 5,000 K. delete delete delete delete The nanofiber web of claim 1 wherein the nanofiber web is used as a mask pack material, wound dressing, artificial skin, drug delivery material or ion exchange membrane. Preparing a mixed solution of polyvinyl alcohol, polyacrylic acid and polyethylene oxide, and electrospinning the mixed solution to form a nanofiber web, The nanofiber web is processed into an insoluble hydrogel using physical crosslinking, Physical crosslinking method is a method of heat treatment at atmospheric pressure or vacuum oven, By adjusting the content of polyacrylic acid 5 to 50 parts by weight with respect to 100 parts by weight of polyvinyl alcohol, the heat treatment temperature 100 to 150 ℃, the heat treatment time in the range of 5 minutes to 6 hours, the degree of crosslinking and discoloration is adjusted, A polyvinyl alcohol has a molecular weight of 10 to 200 K, a polyacrylic acid has a molecular weight of 10 to 1,000 K, and a polyethylene oxide has a molecular weight of 100 to 5,000 K. delete delete delete

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