KR20230049863A - A metal nano fiber bundle coated inorganic composition and manufacturing method thereof - Google Patents

Abstract

A bundled nano-wire according to the present invention has a further reduced fineness compared to conventional metal fibers using drawing methods, etc., and thus has excellent electrical properties such as high sensitivity and high hot electron emission at low temperatures, thereby being used in various fields such as fiber sheets for biosensors or security papers, and filaments for ionizers. A manufacturing method of the bundled nano-wire comprises the steps of: a) forming a coating layer containing an inorganic component on the surface of metal fibers; b) bundling a plurality of the coated metal fibers of step a); and c) stretching the fiber bundle in directions of both ends and locally heating the same to soften the inorganic component and at the same time reduce the diameter of the metal fibers in the fiber bundle to braid the fiber bundle into one fiber.

Description

Bundle type nanowire coated with inorganic component and method for manufacturing the same {A metal nano fiber bundle coated inorganic composition and manufacturing method thereof}

The present invention relates to a method for manufacturing bundled nanowires coated with inorganic components, and in detail, iron, copper, aluminum, cobalt, nickel, tungsten, zirconium, niobium, boron, silicon, chromium, silver, gold, palladium, etc. It is possible to manufacture a single wire by plying various metal fibers composed of various metal components, and it is a bundle coated with an inorganic component that can control the diameter of metal fibers to the nano size through stretching and winding speed control through various heat sources. It relates to a type nanowire and a manufacturing method thereof.

A metal fiber is a fibrous metal having a fine diameter of less than 50 μm, which is generally smaller than a human hair (about 70 to 100 μm), and having a length to diameter of more than 100 times. It has mechanical properties unique to metal, electrical conductivity, heat resistance and corrosion resistance, and is manufactured as a porous body with a porosity of 70% or more through a high-temperature sintering process. , is used as a material for large-area electrodes.

There are several methods for producing such metal fibers, and metal fibers have been developed by a drawing method, and stainless steel fibers having a diameter of 50 μm or less have begun to be commercially used. However, the drawing method has a problem that the process cost rises exponentially as the diameter becomes thinner. process) was developed in 1936. In addition, a cutting method or a rapid cooling solidification method is being used.

However, these methods have several problems. In particular, since metal fibers have a higher weight than other organic fibers, it is difficult to uniformly mix and disperse them with other components, and have poor flexibility. Therefore, in order to solve this problem, it is necessary to manufacture metal fibers of the smallest fineness as possible, but the problem of low productivity and price competitiveness due to manufacturing cost or quality problems has not yet been solved.

Republic of Korea Patent Publication No. 10-2021-0065456 (June 07, 2021)

The present invention has been made to solve the above problems, and the diameter of the metal fiber can be controlled through stretching and winding speed control, while iron, copper, aluminum, cobalt, nickel, zirconium, chromium, silver, gold and palladium It is an object of the present invention to provide a bundled nanowire coated with an inorganic component that can be manufactured into a single wire by plying various metal fibers composed of various metal components, such as, and a manufacturing method thereof.

The present invention relates to a bundled nanowire coated with an inorganic component and a method for manufacturing the same.

One aspect of the present invention,

a) forming a coating layer containing an inorganic component on the surface of the metal fiber;

b) collecting and bundling a plurality of coated metal fibers of step a); and

c) stretching the bundled fibers in both end directions and simultaneously heating them locally to soften inorganic components and at the same time reduce the diameter of metal fibers in the bundle to form a single fiber;

It is characterized in that it includes,

The metal fiber relates to a method for producing a bundled nanowire coated with an inorganic component, characterized in that the diameter before stretching is 20 to 100 μm and the diameter after stretching is 1 to 100 nm.

In the present invention, the metal fiber includes any one or a plurality of metals selected from iron, copper, aluminum, cobalt, nickel, tungsten, zirconium, niobium, boron, silicon, chromium, silver, gold, and palladium,

The inorganic component includes any one or a plurality of inorganic oxides selected from silicon oxide, boron oxide, aluminum oxide, magnesium oxide, calcium oxide, strontium oxide, sodium oxide, potassium oxide, lithium oxide, iron oxide, and titanium oxide. to be

In the present invention, step c) is characterized by heating at a temperature of 800 to 1,200 ° C and stretching at a stretching ratio of 1 to 20.

Another aspect of the present invention is a bundled nanowire manufactured by the above manufacturing method, wherein a plurality of metal fibers are provided inside a fibrous inorganic component in a longitudinal direction, and the bundled nanowire has a fineness of 10 to 100 μm, the fineness of the metal fiber is 1 to 100 nm.

Since the bundled nanowire according to the present invention has a fineness that is further reduced compared to metal fibers to which the conventional drawing method is applied, it has excellent electrical properties such as high sensitivity and high thermal electron emission at low temperatures, so it is a metal for biosensors or security papers. It can be used in various fields such as fiber sheets, electromagnetic shielding, and filaments for ionizers.

1 schematically illustrates a manufacturing process of a bundled nanowire according to the present invention.
2 shows a cross section before stretching and a cross section after stretching of a bundled nanowire according to the present invention.

Hereinafter, examples and comparative examples of the bundled nanowire coated with the inorganic component according to the present invention and a manufacturing method thereof will be described in more detail. However, the specific examples introduced below are provided as examples to sufficiently convey the spirit of the present invention to those skilled in the art.

Therefore, the present invention may be embodied in other forms without being limited to the specific examples presented below, and the specific examples presented below are only described to clarify the spirit of the present invention, but the present invention is not limited thereto.

At this time, if there is no other definition in the technical terms and scientific terms used, they have meanings commonly understood by those of ordinary skill in the art to which this invention belongs, and will unnecessarily obscure the gist of the present invention in the following description. Descriptions of possible known functions and configurations are omitted.

Also, the singular forms used in the specification and appended claims may be intended to include the plural forms as well, unless the context dictates otherwise.

In addition, the drawings introduced below are provided as examples to sufficiently convey the spirit of the present invention to those skilled in the art. Therefore, the present invention may be embodied in other forms without being limited to the drawings presented below, and the drawings presented below may be exaggerated to clarify the spirit of the present invention. Also, like reference numerals denote like elements throughout the specification.

Also, the singular forms used in the specification and appended claims may be intended to include the plural forms as well, unless the context dictates otherwise.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish the component from other components, and the nature, order, or order of the corresponding component is not limited by the term. When an element is described as being “connected,” “coupled to,” or “connected” to another element, that element is directly connected or connectable to the other element, but there is another element between the elements. It will be understood that elements may be “connected”, “coupled” or “connected”.

The method for manufacturing a bundled nanowire according to the present invention,

a) forming a coating layer containing an inorganic component on the surface of the metal fiber;

b) collecting and bundling a plurality of coated metal fibers of step a); and

c) stretching the bundled fibers in both end directions and simultaneously heating them locally to soften inorganic components and at the same time reduce the diameter of metal fibers in the bundle to form a single fiber;

can proceed, including

In the bundled nanowire 10 according to the present invention, as shown in FIG. 2, several metal fibers 11 made of bundles are located in an inorganic component 12, and the metal fibers are coated with inorganic components on the surface. After bundling, the inorganic components are melted and integrated by heating and stretching, and the metal fibers 11 may be manufactured in the form of a glass-metal hybrid composite yarn surrounded by the integrated inorganic components 12.

In the present invention, the metal fiber is manufactured by including one or a plurality of metal components, and may be manufactured by including one or more metal components or metal compounds.

In the present invention, the metal component is not limited to the type as long as it is a component that can be processed into a fiber form by various methods such as melting, cutting, or rapid cooling, and examples of such components include iron, copper, aluminum, cobalt, nickel, tungsten, zirconium, There are niobium, boron, silicon, chromium, silver, gold, palladium, etc., and other components such as carbon, manganese, molybdenum, tungsten, etc. may be added to form a stainless alloy.

Specifically, examples of the case where the above metal components are two or more multi-components may include Ni, NiCr alloy, stainless steel, or FeCr alloy. A suitable commercially available stainless steel metal alloy is Haynes 214 alloy, which is characterized by high resistance to oxidation and high temperatures, and contains about 75% nickel by weight, about 16% chromium by weight, about 4.5% by weight. weight percent aluminum, about 3 weight percent iron, optionally trace amounts of one or more rare earth metals (excluding yttrium), about 0.05 weight percent carbon, and steel making impurities. A useful Haynes 230 alloy may also have a composition containing about 22% chromium, about 14% tungsten, about 2% molybdenum, about 0.10% carbon, traces of lanthanum and the balance nickel.

In addition to the above compositions, it may also include those in which iron is a substantial or major component, for example, FeCr alloys and ferritic stainless steels. The FeCr alloy may contain one or more of nickel, chromium and aluminum, the total amount of these metals advantageously comprising at least about 15% by weight of the alloy, for example about 10 to about 25% by weight of chromium; About 1 to about 8 weight percent aluminum, and 0 to about 20 weight percent nickel, the balance iron.

Also, the FeCr alloy may include a FeCrAl alloy. Such alloys include, for example, about 10 to about 25 weight percent chromium, about 3 to about 8 weight percent aluminum, optional trace amounts of rare earth metals and/or other transition metals, and the balance iron. A suitable FeCrAl alloy is ^Pecraloy® , an alloy having a weight ratio of Fe 72.8/Cr 22/Al 5/Y 0.1/Zr 0.1.

Another example of a ferritic stainless steel is about 20% chromium, about 5% aluminum and about 0.002 to about 0.05% by weight of at least one rare earth metal selected from cerium, lanthanum, neodymium, yttrium and praseodymium or such rare earths. It may contain a mixture of two or more metals, the balance by weight of iron and trace amounts of steelmaking impurities.

The metal components of the above composition are excellent in high temperature resistance, oxidation resistance, and corrosion resistance, and are advantageous in manufacturing metal fibers having a high aspect ratio due to high workability. In addition, the above-mentioned components or other noble metals may be further included in addition to the above components depending on the use, but the present invention is not limited thereto.

In addition, the metal component may be added in the form of an amorphous alloy. Specifically, the metal component includes cobalt, iron, nickel, chromium, molybdenum, carbon, boron, and the like, and the content of the cobalt, iron, and nickel elements is preferably controlled within a certain range.

For example, the amorphous alloy has a composition of (Co, Fe, Ni) ₅₀ (Cr,Mo) _x (C,B) _50-x , as described in Korean Patent Publication No. 10-2015-0141102, cobalt and iron, By adjusting the ratio of nickel, it is possible to secure strength and rigidity while maintaining the physical properties inherent in amorphous. At this time, the ratios of cobalt (Co), iron (Fe), and nickel (Ni) elements in the amorphous alloy are 1:1:1, 2:1:1, 2:2:1, 3:2:1, and 3:3, respectively. It is good to adjust it so that it is included in a ratio of at least one of : 1.

The manufacturing method of the metal fiber is not limited. Basically, any one or a plurality of manufacturing methods known in the art may be applied, and examples of such manufacturing methods include machines such as bundle drawing, shaving, and powder extrusion. processing method; and quench solidification methods such as a crucible melt extrusion (CME) method, a pendant drop melt extraction (PDME) method, a Taylor-Ulitovsky method, and an in rotating water spinning method.

The bundle drawing method is a method in which metal wires are collected in a focusing tube, drawn, and then refocused. Fibers with a diameter of 10 μm or less can be produced through continuous drawing, and in the case of some pure metals, fibers can be made into fibers with a diameter of 2 μm or less, In the case of general metals such as stainless steel, inconel, fecralloy, titanium, and nickel, fibers can be made into diameters of about 4, 8, 12, and 22 ㎛.

The cutting method is a metal fiber manufacturing method developed in Japan. A vibration cutting method that peels off the side of a rotating round bar type metal material with a vibrating bite and a lathe method that cuts the side of a rotating coil with a lathe. and the like, and is advantageous for producing short-fiber metal fibers having a length of less than 3 cm.

The powder extrusion method is a method that applies the principle that metal powder mixed with a separating material is made into a round bar shape and then extruded to transform the powder into a fiber shape while being stretched. has the advantage of controlling

The CME method is a method of extracting metal fibers by bringing a rotating chilled disc into contact with the liquid metal contained in the crucible.

Similar to the CME method, the PDME method is a method of melting a part of a round bar having a diameter of about 10 mm and then contacting it with a rotating chilled disc to extract metal fibers. Fine metal fibers of 20 to 30 ㎛ level can be produced, and due to the high cooling rate of 10 ⁴ to 10 ⁶ °C/sec, fine crystal grains of several ㎛ level, uniformity of components, increase in supersaturation solubility limit, metastable phase and amorphous metal fibers having changes such as formation of an amorphous phase can be prepared.

The Taylor-Ulitowski method is a method of manufacturing metal fibers by wrapping molten metal with a high-viscosity protective material such as pylex glass, drawing it together with the protective material in a semi-molten state, and then chemically removing the protective material to produce metal fibers. It has the advantage of being able to manufacture even metal fibers having a diameter of 1 μm or less.

In the present invention, a more preferred method for producing the metal fiber is the Taylor-Ulitowski method. Since the Taylor-Ulitowski method is a kind of two-component spinning method in which molten metal is spun together with an inorganic component such as glass, the shape of the mold of the spinneret, the viscosity of the molten components, the temperature, etc. It has the advantage of freely adjusting the volume between the coated inorganic components. However, in the case of the Taylor-Ulitowski method, since unnecessary reactions between metal and glass must be prevented, glass having a specific composition must be radiated together.

If the Taylor-Ulitowski method is described in more detail, it is a two-component spinning method in which a metal raw material in which components such as powder or ingot are melted as an island component and a glass component as a sea component, a kind of tube The metal raw material can be placed in the glass component of the shape and spun. The molten liquid metal and glass components can then be drawn through appropriate drawing (stretching) conditions.

According to the Taylor-Ulitowski method, the size of the spinneret used, the pressure of the spinning solution, the spinning speed, etc., can adjust the thickness of the metal fiber or glass component to be coated. For example, in order to reduce the diameter after stretching of the metal fiber, the metal raw material may be spun through a spinneret below a certain level during the manufacturing process, or the spinning pressure of the metal component may be intentionally reduced and the spinning speed may be increased at the same time to increase the spinning speed of the metal fiber. diameter can be reduced.

In addition, the microstructure and mechanical properties of the metal fiber or glass coating layer formed during the process may change depending on the cooling rate. For example, rapid cooling, such as wet or air-wet, increases the strength and hardness of metal fibers, and slow cooling in air reduces the difference in curing speed between the surface and the inside of the metal material, preventing crack formation due to volume expansion. It can be prevented.

Specifically, it is preferable to cool the metal fiber through an air blast wet spinning method. In general, metal materials can obtain a predetermined effect through heat treatment, and such heat treatment includes quenching, tempering, normalizing, annealing, and the like. there is.

Double quenching is an operation to increase the hardness and strength of a material, and is an operation to increase the hardness and strength of the material by heating the material to a certain temperature (austenitization temperature), maintaining it for a certain time, and then cooling it in a coolant.

The present invention is an application of such a quenching method, and by separating the distance from the spinneret to the coolant at least a certain distance during spinning of the metal fiber, crack formation in the metal fiber or coating layer due to rapid cooling can be minimized and at the same time sufficient hardness can be secured. .

At this time, when the metal fiber is spun from the spinneret, it is preferable to first cool it slowly by hot air and then rapidly cool it by being immersed in a coolant again. Specifically, the temperature of the hot air applied during cooling is 300 to 500 ° C. Rapid cooling It is preferable because it can suppress crack formation according to and at the same time prevent interlayer separation between the metal fiber and the coating layer.

In addition, as the main cooling methods used in the heat treatment (especially quenching), there are a water cooling method using water, an oil cooling method using oil, an air cooling method using air, and other furnace cooling methods. is being applied

According to this water cooling method, higher hardness can be obtained during quenching than other cooling methods. However, since deformation such as cracks may occur due to rapid cooling, it is preferable to control the cooling time and the temperature of the coolant.

Specifically, when proceeding with the water cooling method as described above, it is preferable to mix any one or two or more salts selected from potassium nitrate, sodium nitrite, and sodium nitrate with water in order to increase the temperature of water, which is a coolant, and the temperature of the coolant is 200 to 200 °C. Maintaining 300 ° C. is preferable because crack generation due to rapid cooling can be suppressed.

In the present invention, the metal fiber is not limited in fineness or aspect ratio, but it is preferable that the diameter before stretching satisfies 10 to 100 μm. If the diameter before stretching is less than the above range, manufacturing is difficult and there is a risk that the metal fiber may be cut during the stretching process.

In the present invention, the inorganic component is provided to form a coating layer on the surface of the above-described metal fiber, has meltability and is hardened to the extent of forming a coating layer on the surface of the metal fiber at the same time, and melts or It is preferable to have a property of being gelled and bonded, and these inorganic components are glass compositions such as Pyrex-glass, Duran-glass, Fiolax-glass, Simax-glass, etc., characterized by including metal components and other inorganic components along with silicon components. do.

As the silicon component, it is preferable to use silicon oxide. The silicon oxide is also called silica, and is contained in silicate minerals, gravel, sand, etc. in a natural state. In addition, it can be usually classified into quartzite, silica stone, silica sand, etc. according to its size.

It is preferable to use silica sand more preferably as the silicon component. Since silica sand has a high specific surface area, it has low cohesive force, fewer bubbles, and high homogeneity and flatness of the coating layer compared to other types of silicon oxide.

Although the particle size of the silica sand is not limited, it is preferable that the median particle size (D ₅₀ ) is 20 to 100 μm, and more preferably 20 to 30 μm to satisfy the above-described effect and at the same time melt the silica sand more easily. It is desirable because

The silicon component is preferably included in 50 to 70% by weight of 100% by weight of the total composition. When the silicon component is added below the above range, the coating layer is not uniformly formed, and when the silicon component is added above the above range, the weatherability of the composition may deteriorate.

In the present invention, the other inorganic component is characterized in that it includes boron. Examples of such boron compounds include orthoboric acid (H ₃ BO ₃ ), metaboric acid (HBO ₂ ), tetraboric acid (H ₂ B ₄ O ₇ ), boric anhydride (anhydrous B ₂ O ₃ ), and the like, In manufacture of normal alkali-free glass, boric acid anhydride is preferable from the point of being cheap and easy to obtain.

Since boric anhydride as described above suppresses aggregation of the glass raw material, it is possible to suppress the generation of additional bubbles during melting, and the effect of improving homogeneity or flatness is remarkable. In addition, the amount of moisture in the inorganic component can be reduced.

In general, as the average particle diameter of the silica sand decreases, the solubility of the silica sand increases, while the moisture content in the molten composition tends to increase due to the increase in the specific surface area. Moisture in the molten composition may deteriorate the homogeneity and flatness of the coating layer because air bubbles may not be completely removed even through the degassing process, so it is preferable to use boric anhydride to overcome this disadvantage.

Boric anhydride as described above is preferably added in an amount of 5 to 15% by weight based on 100% by weight of the total composition. When boric anhydride is added in an amount less than the above range, the weather resistance of the coating layer may be deteriorated, and when it exceeds the above range, acid resistance and heat resistance of the coating layer may be deteriorated.

In addition, fluorine may be further included as the other inorganic component. The fluorine is added to further improve mechanical properties and weather resistance of the coating layer, and is preferably added in the form of a compound. Examples of the fluorine compound as described above include tin fluoride (SnF ₂ ), lead fluoride (PbF ₂ ), and the like, and these are preferably added in an amount of 0.0001 to 1% by weight of the total composition.

As the metal component, any inorganic component, especially one included in a composition forming a glass film, can be used regardless of the type. These metal components include, for example, any one or a plurality of inorganic oxides selected from aluminum oxide, magnesium oxide, calcium oxide, strontium oxide, sodium oxide, potassium oxide, lithium oxide, iron oxide and titanium oxide, and more preferably preferably contains an alkaline earth metal compound such as magnesium oxide, calcium oxide, or strontium oxide.

Specific examples of such an alkaline earth metal compound include carbonates such as MgCO ₃ , CaCO ₃ , BaCO ₃ , SrCO ₃ , (Mg,Ca)CO ₃ (dolomite), oxides such as MgO, CaO, BaO, and SrO, Mg ( and hydroxides such as OH) ₂ , Ca(OH) ₂ , Ba(OH) ₂ , and Sr(OH) ₂ .

Specifically, as an alkaline earth metal source, for example, (Mg,Ca)CO ₃ (dolomite) alone, alkaline earth metal carbonate alone, a mixture of dolomite and alkaline earth metal hydroxide, a mixture of alkaline earth metal hydroxide and carbonate, and alkaline earth metal Hydroxide alone etc. can be used. As the carbonate, any one or more of MgCO ₃ , CaCO ₃ and (Mg,Ca)CO ₃ (dolomite) is preferably used.

Further, a part or all of the alkaline earth metal source may contain a hydroxide. The content of the hydroxide in this case is not particularly limited, but is preferably in the range of 15 to 100 mol% (in terms of MO) in 100 mol% of the alkaline earth metal source (in terms of MO. However, M is an alkaline earth metal). If the added amount of the hydroxide is 15 mol% or more, the unmelted amount of the SiO ₂ component contained in the silica sand is reduced when the glass raw material is melted, and the unmelted SiO ₂ is introduced into the bubbles when bubbles are generated in the glass melt, resulting in improved homogeneity and stability. Flatness may be reduced.

Commercial examples of such glass components include Pyrex ^ⓡ (SiO ₂ 81 wt %, B ₂ O ₃ 13 wt %, Na ₂ O 4 wt %, Al ₂ O ₃ 2 wt %, Corning), Duran ^ⓡ (SiO ₂ 80.6 wt %). % by weight, B ₂ O ₃ 12.6 wt %, Na ₂ O 4.2 wt %, Al ₂ O ₃ 2.2 wt %, CaO 0.1 wt %, Cl 0.1 wt %, MgO 0.05 wt %, Fe ₂ O ₃ 0.04 wt %, balance Other components of DURAN Group GmbH), Fiolax ^ⓡ (SiO ₂ 75 wt%, B ₂ O ₃ 10.5 wt%, Al ₂ O ₃ 5 wt%, Na ₂ O 7 wt%, CaO 1.5 wt%, remaining amount of other components , Schott), Simax ^ⓡ (SiO ₂ 80.3 wt%, B ₂ O ₃ 13 wt%, Al ₂ O ₃ 2.4 wt%, Na ₂ O, K ₂ O 4.3 wt%, remaining amount of other components) and the like. .

The glass component may be included in an amount of 20 to 40% by weight based on 100% by weight of the total composition. When the glass component is added in an amount less than the above range, the weather resistance of the coating layer may decrease, and if the glass component is added in an amount exceeding the above range, processability is deteriorated and viscosity is increased, which is undesirable.

The inorganic component does not limit the method of forming a coating layer on the surface of the metal fiber. For example, when the Taylor-Ulitowski method is applied as a production method of the metal fiber, it can be produced by spinning with a molten metal component similarly to two-component yarn, and after lowering the melting point by adjusting the composition ratio of the inorganic component It can be applied by immersing or passing a metal component into a molten inorganic component and then curing it.

The coating layer is not limited in thickness. Specifically, the coating layer is preferably softened or melted to a certain extent when heating and stretching the bundled metal fibers to be described later, so that the coating layers of adjacent metal fibers are combined to form a single thickness.

For example, the coating layer may have a thickness of 1 to 20 μm. If the thickness of the coating layer is less than the above range, even if the coating layer is softened by heating, it is difficult to have viscoelasticity, so that plying is not properly performed.

Next, a plurality of coated metal fibers prepared as described above are bundled by collecting them. At this time, the bundling includes a step of winding the plied metal fibers around the bobbin, and the number of strands of the bundled fibers is not limited, but it is preferable to ply 2 to 20 strands as shown in FIG. 2 and the like.

In addition, when the metal fibers are plied in the step b), the twisting process may be further performed simultaneously with the bundling of the metal fibers to impart twist. The twist is to prevent the bundled metal fiber bundles from being easily disturbed in the middle of the process, and the twist direction, number of twists, angle, etc. are not limited, but 2 to 20 T / M (twist) in the S or Z direction per meter), and the twist angle is preferably less than 20°. If the twisting condition is less than the above range, the fiber bundle may be easily disturbed during the stretching process of the metal fiber and the plying may not be performed properly, and if the twisting condition exceeds the above range, cutting of the metal fiber or interfacial separation between the metal fiber and the coating layer may occur may be

Next, as in the step c), the bundled fibers are stretched in both ends and simultaneously heated locally to soften the inorganic components and at the same time reduce the diameter of the metal fibers in the bundle to form a single fiber.

Step c) locally heats and simultaneously applies tension to the multiple metal fibers bundled through step b) to soften the coating layer formed on the surface of each metal fiber and combine with the coating layer of adjacent metal fibers to form one coating layer. formed, and the fineness of the metal fiber inside is reduced by stretching. That is, through step c), a plurality of fiber strands are combined into one fiber, and several metal fibers are located in a state in which the fineness is reduced in one combined fiber.

In step c), as shown in FIG. 1, after unwinding the unwound bobbin 100 in which the bundled metal fibers 10 are plied, the metal fibers unwound from the bobbin pass through the induction coil 200, and then the guide roller 300 and Tension is applied through the elongation roller 400. At this time, the stretching rollers are provided as a pair, and the metal fiber bundle may be heated and plied at the same time as stretching by providing a heating unit 500 between the stretching rollers.

Specifically, the stretching machine for plying the metal fibers includes an unwinding bobbin 100 for supplying bundled metal fibers 10, a winding bobbin 600 for winding the metal fibers supplied from the unwinding bobbin, and the unwinding bobbin. and a pair of elongating rollers 400 formed between the winding bobbin and passed through the metal fibers supplied from the unwinding bobbin to draw them to a desired diameter, and passing the metal fibers between the elongating rollers to apply heat to the metal fibers to be plied. A heating means 500 may be included. In addition, a motor (not shown) is provided on the bobbins or the elongating roller to adjust the rotational speed.

That is, as described above, in the stretching machine, the heating means is provided between the stretching rollers, so that the metal fiber receives tension and heating at the same time. Through this, the heated metal fiber is softened or expanded to a certain extent or more, so that the draw ratio can be further increased. At the same time, the coating layer formed on the surface of each metal fiber is also softened by heat and at the same time receives tension to bond and combine adjacent coating layers.

As shown in FIG. 1, an induction coil 200 may be further provided between the unwinding bobbin and the guide roller. The induction coil is a kind of heat source for providing heat to the bundled nanowires to be manufactured, and is preferably provided as a hollow induction coil as shown in FIG. 1 so that the bundled nanowires pass through the hollow.

Specifically, the hollow induction coil has a structure in which the metal fiber is spirally wound while forming a tubular shape of a predetermined length in the traveling direction, and both ends return in a straight line. Then, the bundled nanowires pass through the spirally wound inside of the hollow induction coil, and if necessary, a ceramic coating layer or tube on the inner surface of the induction coil to prevent the bundled nanowires and the induction coil from being energized. It is good to install etc.

The induction coil can effectively control the range or temperature of the heat source. For example, the temperature of the induction coil can be increased or decreased by controlling the amount of current supplied. At this time, the heating temperature of the induction coil is not limited, but can be adjusted within the range of 300 to 600° C. to soften the coating layer of the metal fiber.

The heating unit 500 preferably maintains an argon or nitrogen atmosphere or a low vacuum state so that the coating layer formed through the above-described process is not destroyed by oxidation, and locally heats the metal fiber at a temperature of 800 to 1,200 ° C. It is good to do. When the heating temperature is less than the above range, stretching of the metal fibers and softening of the coating layer are not performed properly, and when the heating temperature exceeds the above range, the coating layer is melted, the thickness is not uniform, and the flatness may be deteriorated.

The stretching of the step c) may be performed by changing the rotational speed of the unwinding bobbin 100 for supplying the metal fiber bundle and the winding bobbin 600 for rewinding, or by changing the rotational speed between the stretching rollers 400. In this case, the present invention does not limit the drawing ratio of the metal fiber, but it is preferable to adjust the drawing ratio to 1 to 20. When the stretching ratio is less than the above range, the coating layer may not be properly softened or bonded, and when the stretching ratio is above the above range, metal fibers in the coating layer may be cut.

The stretching or heat treatment in step c) may be repeated several times as needed. This is to compensate for the fact that expansion or softening according to temperature may not be properly performed depending on the material of the metal fiber or coating layer. Stretching and cooling may be sequentially performed several times by alternately providing means.

Finally, the stretched metal fiber as described above is formed as a single fiber strand, but inside the coating layer, metal fibers having a reduced diameter compared to before stretching have a form in which several strands are arranged. After the elongation is completed, the metal fiber is washed with water or cleaned as necessary, and then is wound around a winding roller.

The present invention may include a bundled nanowire manufactured by the above manufacturing method. As described above, the bundled nanowire is coated with a plurality of metal fibers provided inside the fibrous inorganic component in the longitudinal direction. At this time, the bundled fibers may be adjusted according to the fineness of the metal fibers, the material of the coating layer, the stretching ratio, the heating temperature, etc. during the manufacturing process, but the total diameter including the coating layer is 10 to 200 μm, and the fineness of the internal metal fibers is 1 to 200 μm. It is characterized by being 100 nm.

Since the bundled nanowire according to the present invention has a fineness that is further reduced compared to metal fibers to which the conventional drawing method is applied, it has excellent electrical properties such as high sensitivity and high thermal electron emission at low temperatures, so it is a metal for biosensors or security papers. It can be used in various fields such as fiber sheets, electromagnetic shielding, and filaments for ionizers.

Hereinafter, the present invention will be described in more detail by way of Examples and Comparative Examples. However, the following examples are only one example for explaining the present invention in more detail, and the present invention is not limited to the following examples.

The physical properties of the specimens prepared through the following Examples and Comparative Examples were measured as follows.

(optical properties)

The appearance and color change were observed with the naked eye using a color copier (Lotte Canon CLC1150) and a scanner (AGFA DUOSCAN, EPSON PERFECTION 2400PHOTO) on security paper inserted into paper, and an instrument irradiated in the infrared region with an excitation wavelength of 980 nm ( Chroma-Calc 3.2 & MF45 IR spectrophotometer from Datacolor, Lambda 9 UV/VIS/NIR spectrophotometer from Perkin-Elmer) were used to check the intensity of emission and detection.

(current measurement)

In order to measure the anode current of the specimens prepared through Examples and Comparative Examples, after connecting each power supply to the cathode and anode, an ammeter was installed between the anode and the anode power supply to generate at the cathode and flow to the anode The strength of the current was measured. At this time, the measurement of the anode current was carried out in a high vacuum of 1.0 × 10 ^-5 to 9.0 × 10 ^-6 torr, and the vacuum environment was confirmed through a vacuum gauge. In addition, the cathode voltage was adjusted to 1.5 to 10 V, and the anode voltage to 30 to 400 V range.

(diameter measurement)

In order to measure the diameter of a metal fiber, a transmission electron microscope (manufactured by Nippon Electronics Co., Ltd.; JEM-1011) was used for bright field observation at an accelerating voltage of 100 kV and a magnification of 40,000 times to obtain an observation image and to measure an accurate diameter. For this purpose, after enlarging the captured original image to twice the size, using software (Motic Image Plus2.1S), the average diameter and whether or not it was cut were measured according to the above definition. Otherwise, it was judged as ×.

(Example 1)

As a metal fiber, a metal fiber made of amorphous alloy ((Co ₂ FeNi) ₅₀ (CrMo) ₃₀ (CB) ₂₀ ) (50㎛ in diameter was prepared, and the metal fiber was added to the molten glass component (Pyrex ^ⓡ ) to coat the surface. After passing through it and curing it in air at room temperature (20° C.), the coated glass component was polished to have a thickness of 10 μm.

Next, 10 strands of the metal fibers were plied and wound, and then the metal fibers were supplied from the winding roller to the drawing roller while passing through a heater so that the metal fibers were stretched and the coating layer was softened at the same time so that they were physically completely plied. At this time, the temperature of the heater was 850 ℃, and the speed of the winding roller and the stretching roller was adjusted so that the stretching ratio was 10.

(Example 2)

Specimens were prepared in the same manner as in Example 1 except that the draw ratio was set to 25 when manufacturing the fiber.

(Example 3)

In Example 1, the metal fiber was manufactured using a wet-air method. Specifically, a metal fiber (50㎛ in diameter) made of amorphous alloy ((Co ₂ FeNi) ₅₀ (CrMo) ₃₀ (CB) ₂₀ ) was prepared as a metal fiber, and the molten glass component (Pyrex ^ⓡ ) was added to the surface to coat the Water as a coolant was spun through a metal fiber, the distance between the spinneret and the coolant was maintained at 50 cm, hot air heated to 400 ° C was continuously supplied between the spinneret and the coolant, and the temperature of the coolant was adjusted to 250 ° C. Specimens were prepared in the same way except for .

(Example 4)

In Example 3, when manufacturing metal fibers, the metal fibers were spun from the spinneret using the wet method and obtained as a coolant at the same time.

(Example 5)

Specimens were prepared in the same manner as in Example 3, except that the temperature of the hot air was set to 200 ° C. when manufacturing the metal fiber.

(Example 6)

Specimens were prepared in the same manner as in Example 3, except that the temperature of the coolant was set to 350 ° C. when manufacturing metal fibers.

(Comparative Example 1)

Specimens were prepared in the same manner as in Example 1 except that stretching was not performed during fiber production.

(Comparative Example 2)

Specimens were prepared in the same manner as in Example 1 except that the coating layer was not formed during the manufacture of fibers.

[Table 1]

Table 1 above measures the maximum value of the anode current with the cathode voltage fixed at 10V. The greater the maximum anode current, the greater the thermionic emission generated from the metal fiber, and the higher the efficiency when used as an ionizer. can

As shown in Table 1, it can be seen that the metal fiber manufactured according to the present invention did not break while maintaining a diameter of 15 μm or less through stretching, and thus exhibited a high maximum value of anode current. However, in the case of Example 2 with a high draw ratio, the maximum value of current rather decreased as a part of the metal fiber was cut, and the maximum value of current decreased in Comparative Example 1 in which no drawing was performed or Comparative Example 2 in which no coating layer was formed. Able to know. In particular, when the coating layer was not formed as in Comparative Example 2, it was confirmed that elongation of the metal fibers was induced during the softening and physical bonding of the coating layer.

In addition, Example 3, in which metal fibers were manufactured using the wet-air method, showed the best maximum value of anode current. This seems to be because, when nanocrystals are formed by cooling, fine nanocrystals are formed because they are not rapidly cooled, and the contact area between crystals increases, further increasing the current flow. However, apart from this, in Examples 4 to 6 in which the wet-drying was not performed or the temperature conditions were different, the crystals were rapidly formed or the formation was slow, so the current flow was also reduced, and additionally, interlayer separation between the metal fibers and the coating layer occurred.

(Examples 7 to 8 and Comparative Examples 3 to 4)

Metal fiber sheets were prepared using the specimens prepared in Examples 1 to 3 and Comparative Examples 1 to 2. Specifically, 20% by weight of conductive pigment (Dental SD 100 (15% by weight), Dental WK 500 (5% by weight), Otsuka Chemical) in 75% by weight of varnish for PET (polyester compound, medium for PET, Daehan Paint) was added and stirred slowly to ensure sufficient mixing, and 2.5% by weight of methyl ethyl ketone and 2.5% toluene were added and stirred to prepare an ink composition.

After immersing the specimen prepared in Examples 1 and 2 and Comparative Examples 1 and 2 in the ink composition prepared as above for 1 minute, it was taken out and dried so that the ink composition was coated on the surface of the specimen. Then, it was put into a conventional metal wire input method in a circular net paper machine and directly inserted into a single paper pencil to manufacture a concealed security paper in which metal fibers are completely inserted.

[Table 2]

As shown in Table 2, it can be seen that the metal fiber manufactured according to the present invention turns black during copying, so it can be confirmed that it has an effect of preventing forgery and falsification.

In the above, preferred embodiments of the present invention have been described, but the scope of the present invention is not limited only to the specific embodiments as described above, and those skilled in the art can appropriately within the scope described in the claims of the present invention. change will be possible.

10: bundled nanowire
11: metal fiber
12: inorganic component (coating layer)
100: winding bobbin
200: induction coil
300: guide roller
400: elongation roller
500: heating means
600: winding bobbin

Claims (6)

a) forming a coating layer containing an inorganic component on the surface of the metal fiber;
b) collecting and bundling a plurality of coated metal fibers of step a); and
c) stretching the bundled fibers in both end directions and simultaneously heating them locally to soften inorganic components and at the same time reduce the diameter of metal fibers in the bundle to form a single fiber;
It is characterized in that it includes,
The method of manufacturing a bundled nanowire coated with an inorganic component, characterized in that the metal fiber has a diameter of 20 to 100 μm before stretching and a diameter of 1 to 100 nm after stretching.
According to claim 1,
The metal fiber is an inorganic component characterized in that it contains any one or a plurality of metals selected from iron, copper, aluminum, cobalt, nickel, tungsten, zirconium, niobium, boron, silicon, chromium, silver, gold and palladium Method for manufacturing coated bundled nanowires.
According to claim 1,
The inorganic component includes any one or a plurality of inorganic oxides selected from silicon oxide, boron oxide, aluminum oxide, magnesium oxide, calcium oxide, strontium oxide, sodium oxide, potassium oxide, lithium oxide, iron oxide, and titanium oxide. A method for producing a bundled nanowire coated with an inorganic component.
According to claim 1,
Step c) is a method for producing a bundled nanowire coated with an inorganic component, characterized in that the heating at a temperature of 800 to 1,200 ℃.
According to claim 1,
Step c) is a method for producing a bundled nanowire coated with an inorganic component, characterized in that the stretching is performed at a stretching ratio of 1 to 20.
A bundled nanowire manufactured by the manufacturing method according to any one of claims 1 to 6, wherein the bundled nanowire has a plurality of metal fibers provided in the longitudinal direction inside the fibrous inorganic component,
The bundled nanowire coated with an inorganic component, characterized in that the fineness of the bundled nanowire is 10 to 100㎛, the fineness of the metal fiber is 1 to 100㎚.

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