KR102780110B1 - Preparation method of crystallized fiber using alkali halide and halogen compounds - Google Patents

Abstract

The present invention relates to a method for producing a high-purity crystalline fiber by an evaporation drying method in which an ionic molten solution of an alkali halide compound or a halide is continuously passed between supports while being evaporated and dried by heating. According to the present invention, a crystalline fiber continuously grown with high purity at normal pressure and low temperature can be produced without using expensive equipment, and thus a crystalline fiber having excellent biocompatibility, biodegradability, and piezoelectricity can be produced economically in terms of cost and energy.

Description

{PREPARATION METHOD OF CRYSTALLIZED FIBER USING ALKALI HALIDE AND HALOGEN COMPOUNDS}

The present invention relates to a method for manufacturing a crystalline fiber using an alkali halide compound and a halide, and more specifically, to a method for manufacturing a crystalline fiber in which an ionic substance in an aqueous solution diffuses through a space subjected to a shear stress by an evaporation drying method to manufacture the crystalline fiber, a piezoelectric body using the crystalline fiber, and a piezoelectric element application product including the piezoelectric body.

Piezoelectricity refers to electricity and its phenomenon that is generated from polarization created by pressure. A piezoelectric element is an element that generates voltage by applying pressure (piezoelectric effect) or deforms by applying voltage (inverse piezoelectric effect).

Piezoelectric materials are applied in various fields such as communication devices (resonators, filters, piezoelectric speakers, piezoelectric transformers, etc.), medical devices (ultrasonic blood flow meters, ultrasonic cleaners, etc.), sensors (acceleration sensors, pressure sensors, etc.), displays (piezoelectric motors, ultra-precision actuators, printer heads, etc.), and energy harvesting.

Piezoelectric materials are classified into single crystals, ceramics, and thin films. Currently, the mainstream piezoelectric ceramic material is PZT [Pb(Zr,Ti)O ₃ ], which is a ferroelectric compound with a perovskite structure based on lead. PZT materials cause fatal poisoning problems in the human body, and lead volatilization causes environmental pollution. Therefore, interest in the development of environmentally friendly lead-free piezoelectric materials is gradually increasing to fundamentally solve this problem.

Conventional piezoelectric single crystals are manufactured by methods such as the Bridgman method, Bernoulli method, Czochralski method, melting method, traveling heater method (THM), sublimation method, Kyropoulos method, flux method, hydrothermal synthesis method, zone melting method, physical vapor transport method, chemical vapor transport method, and heat exchange method. Most of these conventional single crystal growth methods must be performed under high temperature or high pressure conditions, and expensive equipment must be used to perform the process under such conditions, which results in high manufacturing costs.

Meanwhile, when producing salt using seawater in a salt farm, a lot of labor and energy are required for the repeated heating and recovery of the seawater, and the crystals that continuously accumulate during the evaporation process accumulate on the evaporation surface and pump parts, which not only reduces efficiency and causes malfunctions, but the salt produced in this way may contain contaminants such as heavy metals, environmental substances, and trace bacteria derived from the salt farm bottom material, raising safety issues.

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KR 10-1748858 B US 8946974 B

One object of the present invention is to provide an economical method for producing a continuously grown crystalline fiber at atmospheric pressure and low temperature using a molten solution of an alkali halide compound or a halide.

Another object of the present invention is to provide a method for manufacturing a high-purity crystalline fiber that can implement new performances suitable for the purpose of an application field as a new eco-friendly material.

Another object of the present invention is to provide an economical method for producing safe and hygienic salt that does not contain harmful components derived from salt pan bottom materials without requiring much labor and energy by crystallizing sodium chloride from seawater, which is a representative example of an aqueous solution of halides.

Another object of the present invention is to provide a piezoelectric material having excellent biocompatibility, biodegradability and piezoelectricity, comprising a crystalline fiber manufactured by the method of the present invention.

Another object of the present invention relates to a piezoelectric element using a crystalline fiber manufactured by the method of the present invention.

One aspect of the present invention to achieve the above-described purpose is:

A step of preparing an ionic molten solution by mixing an alkali halide compound or a halide into a solvent;

A step of preparing a slurry by mixing a porous solid material into the ionic melt obtained in the previous step;

A step of compressing and packing the above slurry inside a carrier so that there are no pores;

The present invention relates to a method for producing a crystalline fiber using an alkali halide compound or a halide, including a step of heating a slurry-compressed packing support to grow crystals while evaporating and drying to obtain a crystalline fiber.

The above alkali halide compound may be selected from the group consisting of LiF (lithium fluoride), LiCl (lithium chloride), LiBr (lithium bromide), LiI (lithium iodide), NaF (sodium fluoride), NaCl (sodium chloride), NaBr (sodium bromide), NaI (sodium iodide), KF (potassium fluoride), KCl (potassium chloride), KBr (potassium bromide), KI (potassium iodide), RbF (rubidium fluoride), RbCl (rubidium chloride), RbBr (rubidium bromide), RbI (rubidium iodide), CsF (cesium fluoride), CsCl (cesium chloride), CsBr (cesium bromide), CsI (cesium iodide), and mixtures thereof.

The above halide may be selected from the group consisting of TlCl (thallium chloride), TlBr (thallium bromide), TlI (thallium iodide), InCl (indium chloride), InBr (indium bromide), InI (indium iodide), SnCl ₂ (tin (II) chloride), SnBr ₂ (tin (II) bromide), SnI ₂ (tin (II) iodide), BiCl ₃ (bismuth (III) chloride), BiBr ₃ (bismuth (III) bromide), BiI ₃ (bismuth (III) iodide), and CuI (copper iodide).

The solvent usable for producing the ionic molten solution may be at least one selected from the group consisting of alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, and hydrocarbon solvents.

The concentration of the ionic melt of the above alkali halide compound or halide may be 5 to 40 wt%. When mixing the above alkali halide compound or halide with a solvent, heating or stirring may be performed as necessary. For example, mixing may be performed at room temperature or high temperature of 25°C to 70°C for 0.5 to 2 hours at about 350 to 450 rpm.

Porous solid materials usable in the present invention include silicate, sodium silicate, sodium meta silicate, lithium silicate, fumed silica, silicon dioxide, magnesium aluminum silicate, magnesium calcium silicate, aluminum calcium silicate, magnesium aluminum calcium silicate, aluminum oxide, germanium oxide, zirconium oxide, boric anhydride, activated carbon, super activated carbon, microcrystalline cellulose, cellulose fiber, zeolite, montmorillonite, hectorite, It consists of magadite, kenyaite, kaolinite, saponite, beidelite, nontronite, vermicullite, swellable mica, synthetic mica, kanemite, smectite, illite, chlorite, muscovite, pyrophyllite, antigorite, glauconite, vermiculite, sepiolite, imogolite, sobockite, nacrite, anauxite, sericite, ledikite, chrysotile, and antigorite. Nanoparticles may be composed of materials selected from the group consisting of, but are not necessarily limited to, these.

The ionic molten liquid is mixed with the porous solid material in a weight ratio of 7:2 to 9:2 and uniformly mixed at about 100 to 200 rpm to produce a slurry having a viscosity of 100,000 to 200,000 cP at room temperature.

The above-mentioned carrier is a columnar (channel) carrier that accommodates a slurry containing a porous solid material, the diameter of the carrier is 10 mm to 50 mm, and the length of the carrier is within the range of 3 to 6 cm.

In the evaporation drying step of the above-mentioned carrier, the heating temperature due to thermal diffusion that causes material movement of the ionic aqueous solution occurring in the microvolume pores is preferably set to 25 to 100°C, and the humidity in the evaporation drying step is preferably set to 10 to 50%.

Another aspect of the present invention for solving the above-described problem relates to a piezoelectric element comprising an alkali halide compound or a halide crystalline fiber obtained by the above-described method.

The above piezoelectric element may be an energy harvesting device, a sensor, an actuator, a transducer, a transformer, or a sonar.

Another aspect of the present invention is:

A step of preparing a slurry by mixing seawater with a porous solid material;

A step of compressing and packing the above slurry inside a carrier so that there are no pores;

The present invention relates to a method for producing salt, including a step of obtaining salt crystals by heating a slurry-compressed packing support with solar heat to evaporate and dry the crystals while growing the crystals.

According to the method of the present invention, a high-density alkali halide compound or halide crystalline fiber can be economically manufactured by continuously growing it at atmospheric pressure and low temperature without expensive equipment or creating extreme conditions, saving energy and at low cost.

In addition, according to the evaporation drying method using the carrier of the present invention, salt that does not contain foreign substances such as heavy metals, environmental hormones, and bacteria that may be harmful to the human body can be manufactured at a low cost. The salt manufactured in this way can be used as a fire extinguisher for soft metals, a preservative, a disinfectant, a defrosting agent, an anti-fungal agent, a stain remover, etc.

Figure 1 is a flow chart explaining a method for manufacturing a crystalline fiber using an alkali halide compound and a halide according to the present invention.
Figure 2 shows a scanning electron microscope (SEM) photograph of a LiCl crystalline fiber manufactured in an embodiment of the present invention.
Figure 3 shows an SEM photograph of a NaCl crystalline fiber manufactured in an embodiment of the present invention.
Figure 4 shows an SEM photograph of a KCl crystalline fiber manufactured in an embodiment of the present invention.
FIG. 5 shows a scanning electron microscope (SEM) photograph of a KCl crystalline fiber manufactured in an embodiment of the present invention.
Figure 6 shows an EDS spectrum of a KCl crystalline fiber manufactured in an embodiment of the present invention.
Figure 7 shows the pressure of KCl crystalline fibers manufactured in an embodiment of the present invention.
This is a graph of voltage characteristics according to the voltage.
FIG. 8 is a graph showing the results of X-ray diffraction (XRD) analysis of NaCl crystalline fibers mass-produced in seawater in an embodiment of the present invention.
Figure 9 shows an SEM photograph of an RbCl crystalline fiber manufactured in an embodiment of the present invention.
Figure 10 shows an SEM photograph of a CsCl crystalline fiber manufactured in an embodiment of the present invention.
FIG. 11 is a schematic perspective view of a device capable of mass-producing NaCl crystalline fibers manufactured in an embodiment of the present invention using seawater, a seawater (seawater) fixative, and a solar thermal collector.

The present invention is described in more detail below.

The term ‘porous solid material’ in this specification means a solid material composed of nanoparticles having an average particle diameter of 10 nm to 30 nm, which are accommodated in a support to form pores (microscopic volume spaces) for crystalline fiber growth.

In this specification, the ‘carrier’ is a columnar case that accommodates a porous solid material made of metal, plastic, ceramic, and/or glass, having a diameter of about 10 mm to 50 mm and a length of about 3 to 6 cm.

Figure 1 is a flow chart explaining a method for manufacturing a crystalline fiber using an alkali halide compound and a halide according to the present invention.

Referring to FIG. 1, in a method for manufacturing a crystalline fiber using an alkali halide compound or halide of one embodiment of the present invention, first, an alkali halide compound or halide is mixed with a solvent to manufacture an ionic molten liquid (S10). Next, a porous solid material is mixed with the ionic molten liquid obtained in the previous step to manufacture a slurry (S20). The slurry is compressed and packed inside a carrier so that there are no pores (S30). The carrier in which the slurry is compressed and packed is heated to grow crystals while evaporating and drying according to a temperature and concentration gradient to obtain a crystalline fiber (S40).

In the method of the present invention, a high-purity crystalline fiber is manufactured by an evaporation drying method in which an ionic substance of an alkali halide compound or a halide is mixed in a solvent and the molten solution is continuously passed between carriers while heating.

The upper part of the carrier is open, and the temperature of the upper part is low due to evaporation, and since crystal nuclei are formed at the upper part, the concentration increases as it goes toward the upper part. In this way, in the present invention, when a molten solution containing an alkali halide compound or a halide passes through the carrier, temperature and concentration gradients are formed according to the height difference of the carrier as it evaporates by capillary phenomenon between the micro spaces of the carrier. At this time, a continuous crystalline fiber can be manufactured due to the effect of arranging and self-assembling the ion crystals by receiving shear stress through the micro pores. Therefore, it forms a regular three-dimensional array in space as a highly crystallized and well-organized particle.

Non-limiting examples of the above alkali halide compounds may include LiF (lithium fluoride), LiCl (lithium chloride), LiBr (lithium bromide), LiI (lithium iodide), NaF (sodium fluoride), NaCl (sodium chloride), NaBr (sodium bromide), NaI (sodium iodide), KF (potassium fluoride), KCl (potassium chloride), KBr (potassium bromide), KI (potassium iodide), RbF (rubidium fluoride), RbCl (rubidium chloride), RbBr (rubidium bromide), RbI (rubidium iodide), CsF (cesium fluoride), CsCl (cesium chloride), CsBr (cesium bromide), CsI (cesium iodide), and mixtures thereof.

In addition, halides that can be used include TlCl (thallium chloride), TlBr (thallium bromide), TlI (thallium iodide), InCl (indium chloride), InBr (indium bromide), InI (indium iodide), SnCl ₂ (tin (ii) chloride), SnBr ₂ (tin (ii) bromide), SnI ₂ (tin (ii) iodide), BiCl ₃ (bismuth (iii) chloride), BiBr ₃ (bismuth (iii) bromide), BiI ₃ (bismuth (iii) iodide), CuI (copper iodide), and mixtures thereof.

In the present invention, solvents that can be used to form an ionic melt of an alkali halide compound or a halide and to adjust the evaporation rate include polar organic solvents such as alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, etc., and hydrocarbon solvents. As alcohol solvents, monohydric alcohols having 1 to 18 carbon atoms such as ethanol, isopropyl alcohol, amyl alcohol, 4-methyl-2-pentanol, cyclohexanol, 3,3,5-trimethylcyclohexanol, furfuryl alcohol, benzyl alcohol, diacetone alcohol, dihydric alcohols having 2 to 12 carbon atoms such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, and partial ethers thereof. Examples of ether solvents include dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, and diisoamyl ether; cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; and aromatic ring-containing ether solvents such as diphenyl ether and anisole. Examples of ketone solvents include chain ketone solvents such as acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl iso-butyl ketone, 2-heptanone, ethyl-n-butyl ketone, methyl-n-hexyl ketone, di-iso-butyl ketone, and trimethylnonanone; cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, and methylcyclohexanone; and 2,4-pentanedione, acetonylacetone, and acetophenone. Amide solvents include cyclic amide solvents such as N,N'-dimethylimidazolidinone and n-methylpyrrolidone; chain amide solvents such as n-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and n-methylpropionamide. Examples of the ester solvent include monohydric alcohol carboxylate solvents such as ethyl acetate, butyl acetate, benzyl acetate, cyclohexyl acetate, ethyl lactate, and ethyl 3-methoxypropionate; polyhydric alcohol partial ether carboxylate solvents such as monocarboxylate of alkylene glycol monoalkyl ether and monocarboxylate of dialkylene glycol monoalkyl ether; cyclic ester solvents such as butyrolactone; carbonate solvents such as diethyl carbonate; and polyhydric carboxylic acid alkyl ester solvents such as diethyl oxalate and diethyl phthalate. Examples of the hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, iso-propylbenzene, diethylbenzene, iso-butylbenzene, triethylbenzene, di-iso-propylbenzene, and n-amylnaphthalene.

The solvents used in the present invention have different specific heat capacities and thus require different heat energy for evaporation. Therefore, the degree of evaporation and diffusion is different, so that the crystal growth speed can be controlled. Through this, crystal growth energy can be supplied according to the alkali halide compound or halide. Basically, distilled water with a specific heat capacity of 1 Cal/g·℃ is used as the basic solvent. When mixing a different type of solvent in the aqueous solution to control the degree of evaporation and diffusion, acetone, tetrahydrofuran, ethanol, and N,N-dimethylformamide can be used, and the content of distilled water in the mixed solvent is preferably 10 to 50 wt%.

The concentration of the ionic melt of the alkali halide compound or halide may be 5 to 40 wt%. If the concentration of the ionic melt of the alkali halide compound or halide is less than 5 wt%, the minimum quantitative standard for growing crystals after nucleation and forming a fiber cannot be reached, and thus a crystalline fiber cannot be obtained. On the other hand, if it exceeds 40 wt%, the critical concentration for nucleation is quickly reached, and the crystals solidify in the gaps between the nanoparticles in the carrier and cannot grow in the form of a crystalline fiber.

After mixing an alkali halide compound or a halide with a solvent to produce an ionic molten solution, a porous solid material is mixed into the ionic molten solution to produce a slurry. The ionic molten solution is mixed with the porous solid material in a weight ratio of 7:2 to 9:2 and uniformly mixed at 100 to 200 rpm to produce a slurry having a viscosity of 100,000 to 200,000 cP at room temperature.

The above porous solid material provides microscopic volume spaces for crystalline fiber growth within the support. Porous solid materials usable in the present invention include silicate, sodium silicate, sodium meta silicate, lithium silicate, fumed silica, silicon dioxide, aluminum oxide, germanium oxide, zirconium oxide, boric anhydride, activated carbon, super activated carbon, microcrystalline cellulose, cellulose fiber, zeolite, montmorillonite, hectorite, magadite, kenyaite, kaolinite, saponite, beidelite, Nanoparticles composed of a material selected from the group consisting of nontronite, vermicullite, swellable mica, synthetic mica, kanemite, smectite, illite, chlorite, muscovite, pyrophyllite, antigorite, glauconite, vermiculite, sepiolite, imogolite, sobockite, nacrite, anauxite, sericite, ledikite, chrysotile, and antigorite can be used. The porous solid material is selected from polyvalent silicates containing one or more polyvalent metal elements. At this time, the multivalent metal element is a metal element having a valence of two or more, and may be selected from, for example, metal elements belonging to groups 2 to 5 of the periodic table, and more specifically, may be selected from Mg, Al, Ca, and Ba.

The slurry is compressed and packed in a carrier so as to have no pores (S30), and the carrier in which the slurry is compressed and packed is put into a heating means with only one surface exposed, and the temperature and humidity are adjusted (S40). When the carrier in which the slurry is compressed and packed is placed in the heating means with the temperature and humidity conditions set in this way for a certain period of time and reacted, a temperature and concentration gradient are formed as the solvent evaporates and dries, so that crystals grow and crystalline fibers are created (S50). A forced circulation dryer or a constant temperature and humidity chamber can be used as the heating means. The heating means can include a heat source configured to heat the carrier. The heating speed, temperature, time, and atmosphere can affect the crystallinity and shape of the crystalline fiber. After the solvent evaporates, the alkali halide or halide active material remains in a crystallized state. The crystallized fiber can be separated from the carrier and used.

In the present invention, the micro volume formed by the pores between the porous solid materials in the carrier acts as a substrate that creates nucleation, supersaturation, and single crystal growth necessary for crystallization as the molten solution of an alkali halide compound or a halide, which evaporates and diffuses by capillary phenomenon, is arranged under shear stress. At this time, the diameter of the carrier is 10 mm to 50 mm in consideration of nucleation, supersaturation, and single crystal growth necessary for crystallization.

In the present invention, the length of the carrier may be 3 to 6 cm. If the length of the carrier is less than 3 cm or more than 6 cm, nucleation necessary for crystallization may not occur well, so that crystalline fibers may not be formed. In the present invention, when the slurry of the porous solid material is compression-packed, pores having a size of 10 nm to 30 nm are formed during the evaporation process.

In the present invention, the temperature required for evaporation and diffusion of the melt of the alkali halide compound or halide is 25 to 100°C, and preferably 50 to 80°C. If the temperature is less than 25°C or more than 100°C, the nucleation required for crystallization, supersaturation, and crystallization speed required for single crystal growth change, making it impossible to obtain a uniform crystalline fiber.

In the present invention, the humidity required for evaporation and diffusion of the melt of the alkali halide compound or halide is 10 to 50%, more preferably 20 to 40%. If the humidity is less than 10% or more than 50%, the cooling conditions required for nucleation, supersaturation, and crystal growth rate required for crystallization change, making it impossible to obtain a uniform crystalline fiber.

In the present invention, as the moisture in the molten solution injected into the carrier evaporates, the concentration of the molten solution becomes thicker and nuclei are generated for forming crystals. The concentration necessary for crystallization is 5 to 40 wt% of the alkali halide compound or halide relative to the aqueous solution, more preferably 20 to 30 wt%. If the nucleation concentration is less than 5 wt% or more than 40 wt%, the nucleation and supersaturation conditions change due to the concentration gradient generated by evaporation and diffusion, so that the crystal growth rate changes and it becomes impossible to obtain a uniform crystalline fiber.

Another aspect of the present invention relates to a piezoelectric material using the crystalline fiber manufactured by the method of the present invention described above and a piezoelectric element using the same. The crystalline fiber manufactured by the present invention has excellent biocompatibility, biodegradability and piezoelectric properties, and can be usefully used in the manufacture of piezoelectric elements such as energy harvesting devices, sensors, actuators, transducers, transformers, and sonar.

Since the crystalline fiber manufactured by the present invention can output contact, pressure, shape change, vibration, etc. on a surface as an electric signal, it can be used as a sensor that detects the size of stress applied to the crystalline fiber or the applied position.

Another aspect of the present invention is:

A step of preparing a slurry by mixing seawater with a porous solid material;

A step of compressing and packing the above slurry inside a carrier so that there are no pores;

The present invention relates to a method for producing salt, including a step of obtaining salt crystals by heating a slurry-compressed packing support with solar heat to evaporate and dry the crystals while growing the crystals.

In the present invention, seawater can be used instead of NaCl aqueous solution as an ionic molten solution. When seawater is used, salt can be produced economically by continuously crystallizing sodium chloride from dissolved substances dissolved in seawater. Existing evaporation-based salt production is a method of evaporating seawater using solar heat and recovering the remaining crystals, which requires a lot of labor and energy consumption. According to the method of the present invention, sodium chloride present in seawater can be efficiently produced through an evaporation drying method.

When the technology of the present invention is applied to salt production, a device such as that illustrated in Fig. 11, which includes a seawater fixing inducer and a solar thermal collector, can be used. In this case, the carrier is enlarged, and salt can be mass-produced by an evaporative drying method using solar heat as an energy source without a separate heating means.

Hereinafter, the present invention will be described in more detail through examples. These examples are only intended to explain the present invention more specifically, and the scope of the present invention is not limited by these examples.

Example

Example 1 (Manufacture of LiCl crystalline fiber)

LiCl (ACS reagent, ≥99% Sigma Aldrich) and distilled water were mixed at an initial concentration of 20 wt%, and then melted in a heating stirrer at 25°C and 400 rpm to prepare a LiCl aqueous solution. The LiCl aqueous solution was added to fumed silica having a size of 15 nm and uniformly mixed at 100 rpm to prepare a slurry having a viscosity of 100,000 to 200,000 cP at room temperature. At this time, the aqueous solution was 7 g and the fumed silica was 2 g. The slurry was added to a columnar (channel) carrier filled with silica particles inside a polyethylene tube having a diameter of 15 mm and a height of 30 mm, and compression-packed so that there were no pores inside the carrier. The slurry-packed support was placed upright in a forced convection oven with only one surface exposed, and the inside of the dryer was set to a temperature of 70°C and a humidity of 20%, and left for 48 hours.

Pure LiCl crystalline fibers were produced as a result of crystal growth according to the temperature and concentration gradient for 48 hours under the above conditions. The SEM image of the produced LiCl crystalline fiber is shown in Fig. 2.

Example 2 (Preparation of NaCl crystalline fiber)

Crystalline fibers were manufactured in the same manner as in Example 1, except that a NaCl aqueous solution was used and a constant temperature and humid chamber was used. In order to control the degree of evaporation and diffusion through an elevated temperature and humidity environment, the slurry-packed carrier was placed upright in the constant temperature and humidity chamber with only one surface exposed. The inside of the constant temperature and humidity chamber was set to a temperature of 80°C and a humidity of 40%, and crystals were grown for 48 hours, resulting in the manufacture of pure NaCl crystalline fibers. The SEM image of the manufactured NaCl crystalline fibers is shown in Fig. 3. The crystalline fibers

Example 3 (Preparation of NaCl crystalline fibers in seawater)

A NaCl crystalline fiber was manufactured in the same manner as in Example 2, except that 1 kg of seawater was concentrated to 20 g using a rotary evaporator instead of a NaCl aqueous solution, and a carrier having a diameter of 500 mm and a length of 75 cm was used.

Example 4 (Preparation of KCl crystalline fiber)

Crystalline fibers were manufactured in the same manner as in Example 1, except that a KCl aqueous solution was used. The microstructure of the manufactured KCl crystalline fibers was measured using a scanning electron microscope (SEM), and the SEM images are shown in Figs. 4 and 5.

In order to confirm the crystal phase of the KCl crystalline fiber manufactured in this example, X-ray diffraction (XRD) analysis was performed, and the results are shown in Fig. 7. Fig. 6 is an EDS spectrum of the KCl crystalline fiber manufactured in this example, and Fig. 8 is a graph of the voltage characteristics according to the pressure application of the KCl crystalline fiber manufactured in this example.

As shown in Fig. 7, in the case of the KCl crystalline fiber of the present invention, peaks due to crystals appear, but in the case of the KCl powder, it was confirmed that no crystal phase appears other than the peaks appearing in the crystalline KCl fiber of the present invention. It was confirmed that the manufacturing method of the present invention produces a crystallized fiber by SEM, XRD, and EDS data.

Example 5 (Preparation of RbCl crystalline fiber)

Crystalline fibers were manufactured in the same manner as in Example 1, except that an RbCl aqueous solution was used. An SEM image of the manufactured RbCl crystalline fiber is shown in Fig. 5.

Example 6 (Preparation of CsCl crystalline fiber)

Crystalline fibers were manufactured in the same manner as in Example 1, except that a CsCl aqueous solution was used. An SEM image of the manufactured CsCl crystalline fiber is shown in Fig. 6.

Comparative Example 1 (Manufacture of LiCl Crystalline Fiber)

An attempt was made to manufacture crystalline fibers by the same method as Example 1, except that the temperature conditions inside the forced circulation dryer were set to 90°C, but LiCl crystalline fibers were not formed.

Comparative Example 2 (Manufacture of NaCl crystalline fibers under different humidity conditions)

The same procedure as Example 2 was performed, except that the humidity conditions in the constant temperature and humidity chamber were set to 5%, but NaCl crystalline fibers were not formed.

Comparative Example 3 (Manufacture of KCl crystalline fibers with different carrier sizes)

The same procedure as Example 3 was followed, except that a carrier having a diameter of 80 mm was used, but KCl crystalline fibers were not formed.

Comparative Example 4 (Manufacture of KCl crystalline fibers under different temperature conditions)

The same procedure as Example 3 was performed, except that the temperature inside the constant temperature and humidity chamber was set to 150°C, but KCl crystalline fibers were not formed.

Comparative Example 5 (Manufacture of KCl crystalline fibers under different humidity conditions)

The same procedure as Example 3 was performed, except that the humidity in the constant temperature and humidity chamber was set to 70%, but KCl crystalline fibers were not formed.

Comparative Example 6 (Manufacture of KCl crystalline fibers under different concentration conditions)

The same procedure as Example 3 was followed, except that a KCl aqueous solution having a concentration of 5 wt% was used, but KCl crystalline fibers were not formed.

Comparative Example 7 (Manufacture of KCl crystalline fibers with different carrier length conditions)

The same procedure as Example 3 was performed, except that a carrier having a length of 1 cm was used as the carrier, but KCl crystalline fibers were not formed.

Comparative Example 8 (Manufacture of RbCl crystalline fibers with different carrier length conditions)

The same procedure as Example 4 was performed, except that a carrier having a length of 15 cm was used, but RbCl crystalline fibers were not formed.

Comparative Example 9 (Manufacture of CsCl crystalline fibers with different carrier size conditions)

The same procedure as in Example 5 was repeated except that a carrier having a diameter of 80 mm was used as the carrier, but CsCl crystalline fibers were not formed.

Comparative Example 10 (Manufacture of KCl crystalline fibers using different solvents)

The same method as Example 3 was performed except that only N,N-dimethylformamide was used as a solvent to prepare the KCl solution, but KCl crystalline fibers were not formed.

Exam example

In order to confirm the morphology of the crystalline fibers obtained in Examples 1 to 6, scanning electron microscope (SEM) photographs were taken of the crystalline fibers manufactured in each example, and the lengths of the fibers were measured, and the results are shown in Table 1 below.

To measure the piezoelectric potential, PDMS was poured onto a crystalline fiber, sealed, and made into a film with a thickness of 0.2-0.5 of 4×4, and then Cu electrode tapes were attached to the front and back of the film, and a 4×4×0.5 PLA substrate was attached to produce a sample. After performing a poling process to generate piezoelectric characteristics by applying an electric field to the sample at 2.0 kV for 20 minutes, the piezoelectric potential was measured, and the results are shown in Table 1.

Molten liquid Carrier diameter (mm) carrier
Length (cm) menstruum density
(wt%) temperature
(℃) RH(%) Fiber length (cm) Piezoelectric potential
(v) Example 1 LiCl 15 3 Distilled water 20 70 10 5 4.8 Example 2 NaCl 15 3 Distilled water 20 80 40 6 6.4 Example 3 NaCl 500 75 sea water 100 70 40 2 8.3 Example 4 KCl 15 3 Distilled water 20 70 10 17 16.2 Example 5 RbCl 15 3 Distilled water 20 70 10 4.4 4.5 Example 6 CsCl 15 3 Distilled water 20 70 10 2.5 3.9 Comparative Example 1 LiCl 15 3 Distilled water 20 90 10 0 - Comparative Example 2 NaCl 15 3 Distilled water 20 70 5 0 - Comparative Example 3 KCl 80 3 Distilled water 20 70 10 0 - 4 in comparison KCl 15 3 Distilled water 20 150 10 0 - Comparative Example 5 KCl 15 3 Distilled water 20 70 60 0 - Comparative Example 6 KCl 15 3 Distilled water 5 70 10 0 - Comparative Example 7 KCl 15 1 Distilled water 20 70 10 0.4 - Comparative Example 8 RbCl 15 15 Distilled water 20 70 10 0 - Comparative Example 9 CsCl 80 3 Distilled water 20 70 10 0 - Comparative Example 10 KCl 15 3 DMF 20 70 10 0 -

As shown in Table 1 above, the crystalline fiber according to the present invention grew to a length of 2.5 cm to 17 cm, and the piezoelectric body using the crystalline fiber manufactured according to the present invention exhibited piezoelectric properties.

The crystalline fiber manufactured by the method of the present invention is a crystalline fiber formed of highly crystallized and well-ordered particles in a regular three-dimensional array in space, and can provide a piezoelectric material and various applications.

The crystallized fiber of the present invention having biocompatibility, biodegradability, and piezoelectricity can be used in disposable nanomotors and sensors. In one embodiment, the piezoelectric material based on the alkali halide compound or halide crystalline fiber of the present invention can be used in medical sensors and nanomotors. In addition, the crystallized fiber of the present invention can be suitably used as an electroacoustic transducer such as a speaker or a buzzer, an actuator, a tactile display, and a power generation device.

While the preferred embodiments of the present invention have been described in detail above, it will be understood that these embodiments are provided by way of example only. Numerous modifications, changes, and substitutions will occur to those skilled in the art without departing from the spirit of the present invention. Accordingly, the appended claims are intended to cover all modifications that fall within the spirit and scope of the present invention.

Claims (16)

A step of preparing an ionic molten solution by mixing an alkali halide compound or a halide into a solvent;
A step of preparing a slurry by mixing a porous solid material into the ionic melt obtained in the previous step;
A step of compressing and packing the above slurry inside a carrier so that there are no pores;
A method for producing a crystalline fiber using an alkali halide compound or a halide, comprising the step of heating a slurry-compressed packing support to grow crystals while evaporating and drying to obtain a crystalline fiber. In the first paragraph, the crystal growth step is,
A step of introducing a slurry-packed carrier into a heating means with only one surface exposed; and
A method for manufacturing a crystalline fiber using an alkali halide compound or a halide, characterized by including a step of reacting a slurry-packed support for a predetermined period of time in a heating means set to a crystal growth temperature and humidity. A method for producing a crystalline fiber using an alkali halide compound or a halide, characterized in that in claim 1, the alkali halide compound is selected from the group consisting of LiF (lithium fluoride), LiCl (lithium chloride), LiBr (lithium bromide), LiI (lithium iodide), NaF (sodium fluoride), NaCl (sodium chloride), NaBr (sodium bromide), NaI (sodium iodide), KF (potassium fluoride), KCl (potassium chloride), KBr (potassium bromide), KI (potassium iodide), RbF (rubidium fluoride), RbCl (rubidium chloride), RbBr (rubidium bromide), RbI (rubidium iodide), CsF (cesium fluoride), CsCl (cesium chloride), CsBr (cesium bromide), CsI (cesium iodide), and mixtures thereof. A method for producing a crystalline fiber using an alkali halide compound or halide, characterized in that in claim 1, the halide is selected from the group consisting of TlCl (thallium chloride), TlBr (thallium bromide), TlI (thallium iodide), InCl (indium chloride), _InBr (indium bromide), _InI (indium iodide), SnCl ₂ (tin (ii) chloride), SnBr ₂ (tin (ii) bromide), SnI ₂ (tin (ii) iodide), BiCl 3 (bismuth (iii) chloride), BiBr ₃ (bismuth (iii) bromide), BiI 3 (bismuth (iii) iodide), and CuI (copper iodide). A method for producing a crystalline fiber using an alkali halide compound or a halide, characterized in that in claim 1, the solvent is at least one selected from the group consisting of an alcohol solvent, an ether solvent, a ketone solvent, an amide solvent, an ester solvent, and a hydrocarbon solvent. A method for producing a crystalline fiber using an alkali halide compound or halide, characterized in that in claim 1, the concentration of the ionic melt of the alkali halide compound or halide is 5 to 40 wt%. In the first paragraph, the porous solid material is selected from the group consisting of silicate, sodium silicate, sodium meta silicate, lithium silicate, fumed silica, silicon dioxide, aluminum oxide, germanium oxide, zirconium oxide, boric anhydride, activated carbon, super activated carbon, microcrystalline cellulose, cellulose fiber, zeolite, montmorillonite, hectorite, magadite, kenyaite, kaolinite, saponite, beidelite, A method for producing a crystalline fiber using an alkali halide compound or a halide, characterized in that the nanoparticle is composed of a material selected from the group consisting of nontronite, vermicullite, swellable mica, synthetic mica, kanemite, smectite, illite, chlorite, muscovite, pyrophyllite, antigorite, glauconite, vermiculite, sepiolite, imogolite, sobokite, nacrite, anauxite, sericite, ledikite, chrysotile, and antigorite. A method for producing a crystalline fiber using an alkali halide compound or a halide, characterized in that in the first paragraph, the slurry preparation step is a step of preparing a slurry having a viscosity of 100,000 to 200,000 cP at room temperature by uniformly mixing an ionic molten liquid and a porous solid material at a weight ratio of 7:2 to 9:2 at 100 rpm to 200 rpm. A method for producing a crystalline fiber using an alkali halide compound or a halide, characterized in that in claim 1, the average particle diameter of the porous solid material is 10 nm to 30 nm. A method for manufacturing a crystalline fiber using an alkali halide compound or a halide, characterized in that in claim 1, the carrier has a diameter of 10 to 50 mm and a length of 3 to 6 cm. A method for manufacturing a crystalline fiber using an alkali halide compound or a halide, characterized in that in the first paragraph, the evaporation drying step in the carrier is performed at a heating temperature of 25 to 100°C. A method for manufacturing a crystalline fiber using an alkali halide compound or a halide, characterized in that in the first paragraph, the humidity in the evaporation drying step is 10 to 50%. A method for producing a crystalline fiber using an alkali halide compound or halide, characterized in that in claim 1, the nucleation concentration according to the concentration of the ionic aqueous solution is 5 to 40 wt%. A piezoelectric element comprising an alkali halide compound or a halide crystalline fiber obtained by any one of the methods of claims 1 to 13. A piezoelectric element in claim 14, characterized in that the piezoelectric element is an energy harvesting device, a sensor, an actuator, a transducer, a transformer, or a sonar. A step of preparing a slurry by mixing seawater with a porous solid material;
A step of compressing and packing the above slurry inside a carrier so that there are no pores;
A method for producing salt, comprising the step of heating a slurry-packed support by solar heat to evaporate and dry while growing crystals to obtain salt crystals.