KR100412241B1 - A ultrafine inorganic fiber, and a process of preparing for the same - Google Patents

Abstract

The present invention relates to an ultrafine inorganic fiber and a method for manufacturing the same, and to mixing and reacting an inorganic material sol (Sol) or gel (Gel) and a thermoplastic resin solution to prepare a mixture thereof, and then electrospinning the mixture solution under high voltage A composite fiber of a type in which a thermoplastic resin surrounds an inorganic material is prepared, and the thermoplastic resin in the composite fiber is carbonized or eluted with a solvent to obtain an ultrafine inorganic fiber having a length of 100 to 10,000 times the diameter and a diameter of 10 to 1,000 nm. Manufacture. Since the ultrafine inorganic fibers of the present invention have a very large specific surface area compared to the volume, it can be utilized as a reinforcing material and coating material in various industrial fields.

Description

Ultrafine inorganic fiber, and a process for preparing the same {A ultrafine inorganic fiber, and a process of preparing for the same}

The present invention relates to an ultrafine inorganic fiber and its manufacturing method which can be applied to all industrial fields having a large specific surface area compared to the volume.

Inorganic particles and inorganic fibers include glass reinforcements, contact lens reinforcements, various coatings, biosensor parts, bulletproof vests, bulletproof helmets, aerospace parts, electronic parts, artificial bones and artificial blood vessels. It can be used in all industries such as materials and heat-resistant materials.

U.S. Patent 5,917,279 describes a method of dispersing inorganic particles having a diameter of 1 to 100 nm on a polymer binder and using them as an interlayer material for an electron branching. After obtaining the by-product surrounding it, there is described a method of preparing the nano-phase inorganic particles by removing the by-product.

In addition, US Pat. No. 6,068,880 discloses a method for separating nanoparticles from a liquid precursor solution by placing a substrate on a rotatable sample holder in a reactor, filling the reactor with a liquid precursor, and then irradiating a laser while rotating the sample holder. This is described.

Conventional inorganic particles prepared as described above have a relatively small length with respect to the diameter compared to the fine inorganic fibers, that is, the specific surface area is relatively small compared to the volume, the effect was not relatively good when used as a reinforcing material.

On the other hand, the egg described in the European Ceramic Society (Jr, European Ceramic Society, Vol 20, 2543-2549, 2000). In the paper by R. Venkatesh, a mixed solution was prepared by adding SiO ₂ sol and polylactic acid or polyvinyl alcohol to an aluminum oxychloride sol having an alumina content of 30.5% by weight, and then sol spinning the mixed solution. A method of producing alumina fibers having a diameter of 10 μm or more is disclosed by calcining the fibers in a gel form and subsequently calcining the fibers at a temperature of 500 ° C. or higher.

As such, since only inorganic fibers having a diameter of 10 μm or more could be manufactured by a known method, there was a limit in increasing the specific surface area to the volume of the inorganic fiber.

The present invention is to provide a method for producing an ultrafine inorganic fiber having a length ratio to the diameter of 100 times or more and a diameter of 10 to 1,000nm using an electrospinning method. In addition, the present invention is to provide a very fine inorganic fiber useful as a reinforcing material and coating material in a variety of industries because the specific surface area to volume is very large.

1 is a schematic view of a process for producing fibers by electrospinning

Figure 2 is an electron micrograph of the composite fiber of the present invention in the form of a polyvinyl alcohol wrapped silica (before carbonization)

Figure 3 is an electron micrograph of the ultrafine inorganic fibers obtained by carbonizing the composite fiber of Figure 2 at 550 ℃

Figure 4 is an electron micrograph of the ultrafine inorganic fibers obtained by carbonizing the composite fiber of Figure 2 at 700 ℃

5 is an electron micrograph of the ultrafine inorganic fibers obtained by carbonizing the composite fiber of Figure 2 at 1,000 ℃

Figure 6 is a differential scanning thermal analysis (DSC) graph of silica / polyvinyl alcohol composite fiber according to the silica content

7 is an X-ray wide-angle diffraction graph of silica / polyvinyl alcohol composite fiber

※ Code explanation for main part of drawing

1: spinning liquid main tank 2: metering pump 3: nozzle

4 collector 5 voltage transfer rod 6 voltage generator

In order to achieve the above-described problems, a method of preparing an ultrafine inorganic fiber according to the present invention includes preparing a mixed solution by mixing and reacting an inorganic material sol (Sol) or gel (Gel) with a thermoplastic resin solution, and then mixing the mixed solution with a high voltage. Electrospinning under to produce a composite fiber of a form in which the thermoplastic resin wraps the inorganic material, characterized in that the thermoplastic resin in the composite fiber is carbonized or eluted with a solvent.

In addition, the ultrafine inorganic fibers of the present invention are characterized in that the length is 100 to 10,000 times the diameter, and the diameter is 10 to 1,000 nm.

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

First, a mixed solution is prepared by mixing and reacting a sol (Sol) or gel (Gel) containing an inorganic material with a thermoplastic resin solution. As the inorganic material, silica, ceramic, or alumina may be used, and as the thermoplastic resin, polyvinyl alcohol, polylactic acid, polyamide, polyester or polypropylene may be used.

For example, in the case of producing ultrafine silica fibers, first, the molar ratio of silica gel: phosphoric acid: distilled water is adjusted to 1 to 5: 0.1 to 1: 10 to 80, followed by stirring, and a polyvinyl alcohol solution is added thereto. It is preferable to prepare a mixed solution of.

Next, the mixed solution is electrospun under high voltage to produce a composite fiber in which a thermoplastic resin surrounds an inorganic material. At this time, the electrospinning is carried out using a conventional electrospinning device.

Specifically, the conventional electrospinning device is a spinning liquid main tank 1 for storing spinning liquid as shown in FIG. 1, a metering pump 2 for quantitative supply of spinning liquid, a plurality of nozzles 3 for discharging spinning liquid, It is composed of a collector (4) for accumulating fibers to be located at the bottom of the nozzle, a voltage generator (6) for generating a voltage, and a mechanism (5) for transferring the generated voltage to the nozzle and the collector. The spinning liquid in the spinning liquid main tank 1 is continuously fed into the plurality of nozzles 3 to which a high voltage is applied through the metering pump 2.

Subsequently, the spinning liquid supplied to the nozzles 3 is spun and concentrated through the nozzles onto the collector 4 under high voltage to form a single fiber web. The voltage during electrospinning is preferably 5 kV or more, and the composite fiber of the inorganic material / thermoplastic resin produced by the electrospinning has a diameter of 1,000 nm or less.

Next, the ultrafine inorganic fiber of the present invention is manufactured by completely removing the thermoplastic resin in the composite fiber by heat-treating or solvent treating the manufactured composite fiber at high temperature. The thermoplastic resin in the composite fiber is carbonized by high temperature heat treatment or eluted and removed by solvent treatment. As the thermoplastic resin surrounding the inorganic material is completely removed, the diameter of the inorganic fiber is further miniaturized.

The ultrafine inorganic fibers of the present invention prepared as described above have a length of 100 to 1,000 times the diameter and a diameter of 10 to 1,000 nm.

As described above, the ultrafine inorganic fibers of the present invention are very thin and have a very large specific surface area to volume, which is more useful as a material for various industrial fields.

Inorganic particles may be prepared by grinding the ultrafine inorganic fibers of the present invention.

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

Example 1

While stirring the silica gel at room temperature, phosphoric acid and distilled water are added thereto in a drop method to adjust the molar ratio of silica gel: phosphoric acid: distilled water to be 1: 0.2: 11 and stirred for 6 hours to prepare a silica gel solution. Meanwhile, polyvinyl alcohol was dissolved in distilled water to prepare a polyvinyl alcohol solution having a concentration of 10%. The polyvinyl alcohol solution was gradually supplied to the silica gel solution, mixed and reacted at 60 ° C. for 12 hours to prepare a silica / polyvinyl alcohol mixture solution. do. Subsequently, the silica / polyvinyl alcohol mixture solution was electrospun under a voltage of 20 kV to prepare silica / polyvinyl alcohol composite fibers having a diameter of 500 nm. An electron micrograph of the composite fiber is shown in FIG. 2. Subsequently, the prepared silica / polyvinyl alcohol was removed to prepare ultrafine silica fibers. An electron micrograph of the prepared ultrafine silica fiber is shown in FIG. 5 and the diameter is 100 nm.

Example 2

Except that the silica / polyvinyl alcohol composite fiber was carbonized at 550 ℃ ultrafine silica fibers were prepared in the same process and conditions as in Example 1. An electron micrograph of the prepared ultrafine silica fibers is shown in FIG. 3.

Example 3

Except that the silica / polyvinyl alcohol composite fiber was carbonized at 700 ° C ultrafine silica fiber was prepared in the same process and conditions as in Example 1. An electron micrograph of the prepared ultrafine silica fibers is shown in FIG. 4.

The ultrafine inorganic fibers of the present invention have a diameter of 1,000 nm or less and have a very high specific surface area to volume, which is very useful as a reinforcing material or coating material in all industrial fields.

Claims (7)

After mixing and reacting an inorganic material sol (Sol) or gel (Gel) and a thermoplastic resin solution to prepare a mixture of these, and then the mixture is electrospun under high voltage to produce a composite fiber in the form of a thermoplastic resin surrounding the inorganic material And eluting the thermoplastic resin in the composite fiber with carbonization or a solvent. The method for producing an ultrafine inorganic fiber according to claim 1, wherein the diameter of the inorganic fiber is 10 to 1,000 nm or less. The method for producing an ultrafine inorganic fiber according to claim 1, wherein the voltage during electrospinning is 5 kV or more. The method of producing an ultrafine inorganic fiber according to claim 1, wherein the inorganic material is silica, ceramic or alumina. The method for producing an ultrafine inorganic fiber according to claim 1, wherein the thermoplastic resin is polyvinyl alcohol, polylactic acid, polyamide, polyester or polypropylene. An ultrafine inorganic fiber having a length of 100 to 10,000 times the diameter and a diameter of 10 to 1,000 nm. The ultrafine inorganic fiber according to claim 6, wherein the inorganic material is silica, ceramic or alumina.