COPPER SULFIDE NANOPARTICLES HAVING CORE-SHELL STRUCTURE INCLUDED IN COATING COMPOSITION FOR BLOCKING NEAR-INFRARED LIGHT, AND PREPARATION METHOD THEREFOR

Abstract

Proposed are copper sulfide nanoparticles having a core-shell structure included in a coating composition for blocking near-infrared light, and a method of manufacturing the same. More particularly, a method of manufacturing copper sulfide nanoparticles having a core-shell structure includes manufacturing CuS nanoparticles, manufacturing Cu.sub.2-xS nanoparticles by heating a mixed solution of the CuS nanoparticles, a reducing agent, and a solvent, and manufacturing Cu.sub.2-xS@Cu.sub.2-yO core-shell nanoparticles by heating a mixed solution of the Cu.sub.2-xS nanoparticles, an oxidizing agent, and a solvent.

Claims

1. A method of manufacturing copper sulfide nanoparticles having a core-shell structure, comprising: manufacturing Cu.sub.2-xS nanoparticles by heating a mixed solution of CuS nanoparticles, a reducing agent, and a solvent; and manufacturing Cu.sub.2-xS@Cu.sub.2-yO core-shell nanoparticles by heating a mixed solution of the Cu.sub.2-xS nanoparticles, an oxidizing agent, and a solvent.

2. The method of claim 1, wherein the copper sulfide nanoparticles having the core-shell structure have a primary particle size of 5 nm to 200 nm and satisfy a Cu/S element ratio of 1 to 2.

3. The method of claim 1, wherein the reducing agent comprises at least one selected from the group consisting of lithium aluminum hydride, diisobutyl aluminum hydride, diborane, lithium borohydride, sodium borohydride, potassium borohydride, formic acid, formaldehyde, acetaldehyde, propyl aldehyde, butyl aldehyde, hexyl aldehyde, decyl aldehyde, dodecyl aldehyde, hexadecyl aldehyde, octadecyl aldehyde, hydrogen sulfide, mercaptomethane, mercaptoethane, mercaptopropane, mercaptobutane, mercaptohexane, mercaptooctane, mercaptodecane, mercaptododecane, mercaptohexadecane, mercaptooctadecane, mercaptomethanol, mercaptoethanol, mercaptopropanol, mercaptobutanol, mercaptohexanol, mercaptooctanol, mercaptodecanol, mercaptododecanol, mercaptohexadecanol, mercaptooctadecanol, mercaptoacetic acid, mercaptopropionic acid, mercaptobutyric acid, mercaptohexanoic acid, mercaptooctanoic acid, mercaptodecanoic acid, mercaptododecanoic acid, mercaptododecanoic acid, mercaptohexanoic acid, mercaptooctanoic acid, mercaptomethylamine, mercaptoethylamine, mercaptopropylamine, mercaptobutylamine, mercaptohexylamine, mercaptooctylamine, mercaptodecylamine, mercaptododecylamine, mercaptohexadecylamine, mercaptooctadecylamine, dimercaptomethane, dimercaptoethane, dimercaptopropane, dimercaptobutane, dimercaptohexane, dimercaptooctane, dimercaptodecane, dimercaptododecane, dimercaptohexadecane, dimercaptooctadecane, cysteine, mercaptopyruvic acid, mercaptosuccinic acid, mercaptomaleic acid, sodium, potassium, lithium, metal amalgam, hydrogen ascorbate, methane, ammonia, carbon monoxide, sodium hydride, lithium hydride, potassium hydride, lithium diisopropyl amine, potassium ethoxide, sodium ethoxide, and lithium ethoxide.

4. The method of claim 1, wherein the oxidizing agent comprises at least one selected from the group consisting of hydrogen oxide, lithium hydroxide, sodium hydroxide, potassium hydroxide, hydrogen peroxide, benzoyl peroxide, dicumyl peroxide, lauroyl peroxide, tert-butyl peroxide, cyclohexanone peroxide, 2,4-pentanedione peroxide, peracetic acid, cumene hydroperoxide, tert-butyl peroxybenzoate, tert-butyl peracetate, tert-butyl hydroperoxide, hydrogen persulfate, lithium persulfate, sodium persulfate, potassium persulfate, ammonium persulfate, hydrogen permanganate, lithium permanganate, sodium permanganate, potassium permanganate, ammonium permanganate, hydrogen manganate, lithium manganate, sodium manganate, potassium manganate, ammonium manganate, hydrogen dichromate, lithium dichromate, sodium dichromate, potassium dichromate, ammonium dichromate, hydrogen chromate, lithium chromate, sodium chromate, potassium chromate, ammonium chromate, hydrogen periodate, lithium periodate, sodium periodate, potassium periodate, hydrogen iodate, lithium iodate, sodium iodate, potassium iodate, hydrogen iodite, lithium iodite, sodium iodite, potassium iodite, hydrogen hypoiodite, lithium hypoiodite, sodium hypoiodite, potassium hypoiodite, hydrogen perbromate, lithium perbromate, sodium perbromate, potassium perbromate, hydrogen bromate, lithium bromate, sodium bromate, potassium bromate, hydrogen bromite, lithium bromite, sodium bromite, potassium bromite, hydrogen hypobromite, lithium hypobromite, sodium hypobromite, potassium hypobromite, hydrogen perchlorate, lithium perchlorate, sodium perchlorate, potassium perchlorate, hydrogen chlorate, lithium chlorate, sodium chlorate, potassium chlorate, hydrogen chlorite, lithium chlorite, sodium chlorite, potassium chlorite, hydrogen hypochlorite, lithium hypochlorite, sodium hypochlorite, potassium hypochlorite, oxygen, ozone, and nitric acid.

5. The method of claim 1, wherein the solvent comprises at least one selected from the group consisting of water, methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, formic acid, acetic acid, formaldehyde, acetaldehyde, methyl acetate, ethyl acetate, butyl acetate, toluene, xylene, benzene, chlorobenzene, dichlorobenzene, trichlorobenzene, pyridine, hexene, cyclohexene, octane, isophorone, dioxane, tetrahydrofuran, chloroform, dichloromethane, carbon tetrachloride, dichloroethane, diethyl ether, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, formamide, dimethylsulfoxide, acetonitrile, propylene carbonate, ethylene glycol, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, diethylene glycol, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, polyethylene glycol, propylene glycol, propylene glycol monobutyl ether, propylene glycol monobutyl ether acetate, propylene glycol monoethyl ether, propylene glycol monoethyl ether acetate, dipropylene glycol, dipropylene glycol monobutyl ether, dipropylene glycol monobutyl ether acetate, dipropylene glycol monoethyl ether, dipropylene glycol monoethyl ether acetate, and polypropylene glycol.

6. Copper sulfide nanoparticles having a core-shell structure, comprising a core represented by Chemical Formula 1 below and a shell represented by Chemical Formula 2 below:
Cu.sub.2-xS  [Chemical Formula 1] in Chemical Formula 1, 0≤x≤1.0; and
Cu.sub.2-yO  [Chemical Formula 2] in Chemical Formula 2, 0≤y≤1.0.

7. The copper sulfide nanoparticles of claim 6, wherein the copper sulfide nanoparticles having the core-shell structure have a primary particle size of 5 nm to 200 nm and a blocking wavelength range of 600 nm to 2500 nm.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0037] FIG. 1 is a flowchart showing a process of preparing a coating composition for blocking near-infrared light;

[0038] FIG. 2 shows the results of analysis of a crystal structure through X-ray diffraction (XRD) of CuS nanoparticles manufactured in Preparation Example 1, Cu.sub.2-x nanoparticles manufactured in Example 1, and Cu.sub.2-xS@Cu.sub.2-yO nanoparticles manufactured in Example 2;

[0039] FIG. 3 shows a transmission electron microscope (TEM) image of the nanoparticles manufactured in Example 2;

[0040] FIG. 4 shows the results of particle size analysis showing the size distribution of the aggregated secondary particles of the nanoparticles manufactured in Example 2; and

[0041] FIG. 5 shows initial transmission spectra and transmission spectra after storage for 100 hours in a thermo-hygrostat chamber (temperature: 85° C., relative humidity: 85%) of coating films including the CuS nanoparticles manufactured in Preparation Example 1, the Cu.sub.2-x nanoparticles manufactured in Example 1, and the Cu.sub.2-xS@Cu.sub.2-yO nanoparticles manufactured in Example 2.

MODE FOR DISCLOSURE

[0042] Hereinafter, preferred embodiments of the present disclosure will be described in detail. However, the present disclosure may be embodied in other forms, rather than being limited to the embodiments described herein. Rather, the present disclosure is provided to sufficiently transfer the spirit of the present disclosure to those skilled in the art such that the content disclosed herein is thorough and complete.

Preparation Example 1. Manufacture of CuS Nanoparticles

[0043] 50 ml of a solution of 4 M copper nitrate in ethylene glycol and 50 ml of a solution of 4 M thiourea in ethylene glycol were mixed and heated at 100° C. for 1 hour with stirring, thus synthesizing CuS nanoparticles. Thereafter, the reaction mixture was cooled to room temperature, centrifuged, washed three times with ethanol and then dried at 60° C., thereby manufacturing a CuS nanoparticle powder.

[0044] Based on the results of X-ray diffraction (XRD) analysis of the CuS nanoparticles thus manufactured, it was confirmed that only the CuS crystal peak appeared.

[0045] Based on the results of measurement of the particle size using a transmission electron microscope, it was confirmed that the primary particle size fell in the range of 5-200 nm.

Example 1. Manufacture of Cu.SUB.2-x.S Nanoparticles

[0046] 10 g of the CuS nanoparticle powder manufactured in Preparation Example above, 2 g of ascorbic acid, and 88 g of ethanol (ethyl alcohol) were placed in a 250 ml round-bottom flask, after which the internal temperature of the flask was raised to 80° C., followed by stirring for 12 hours, thus synthesizing Cu.sub.2-xS nanoparticles. Thereafter, the reaction mixture was cooled to room temperature, centrifuged, washed three times with ethanol and then dried at 60° C., thereby manufacturing a Cu.sub.2-xS nanoparticle powder.

[0047] Based on the results of XRD analysis of the Cu.sub.2-xS nanoparticles thus manufactured, the same peak as that of a CuS crystal was observed, and simultaneously, the same peak as a Cu.sub.1.8S crystal was also observed, indicating that the Cu.sub.2-xS nanoparticles were formed by reducing the CuS nanoparticles.

Example 2. Manufacture of Cu.SUB.2-x.S@Cu.SUB.2-y.O Nanoparticles from Cu.SUB.2-x.S Nanoparticles

[0048] 10 g of the Cu.sub.2-xS nanoparticle powder manufactured in Example 1, 1 g of benzoyl peroxide, and 89 g of ethanol (ethyl alcohol) were placed in a 250 ml round-bottom flask and then stirred at room temperature for 12 hours, thus synthesizing Cu.sub.2-xS@Cu.sub.2-yO nanoparticles from the Cu.sub.2-xS nanoparticles. Thereafter, the reaction mixture was cooled to room temperature, centrifuged, washed three times with ethanol and then dried at 60° C., thereby manufacturing a Cu.sub.2-xS@Cu.sub.2-yO nanoparticle powder from the Cu.sub.2-xS nanoparticles.

[0049] Based on the results of XRD analysis of the Cu.sub.2-xS@Cu.sub.2-yO nanoparticles thus manufactured, the same peak as that of a CuS crystal was observed, and simultaneously, the same peak as that of a Cu.sub.1.8S crystal was also observed. In addition, the peak of a Cu.sub.2O crystal was observed at the time of a decrease in the peak intensity of the Cu.sub.1.8S crystal, indicating that Cu.sub.2O was formed by oxidizing the surface of the Cu.sub.1.8S nanoparticles.

Comparative Example 1. Manufacture of CuS@Cu.SUB.2-y.O Nanoparticles from CuS Nanoparticles

[0050] 10 g of the CuS nanoparticle powder manufactured in Preparation Example above, 1 g of benzoyl peroxide, and 89 g of ethanol (ethyl alcohol) were placed in a 250 ml round-bottom flask and then stirred at room temperature for 12 hours, thus synthesizing CuS@Cu.sub.2-yO nanoparticles from the CuS nanoparticles. Thereafter, the reaction mixture was cooled to room temperature, centrifuged, washed three times with ethanol and then dried at 60° C., thereby manufacturing a CuS@Cu.sub.2-yO nanoparticle powder from the CuS nanoparticles.

[0051] The copper sulfide nanoparticles manufactured in Preparation Example 1, Example 1, Example 2, and Comparative Example 1 were subjected to energy-dispersive X-ray spectroscopy (EDAX). Based on the results thereof, the element ratio is shown in Table 1 below.

TABLE-US-00001 TABLE 1 Element ratio of nanoparticles analyzed through EDAX Cu S O CuS nanoparticles (Preparation Example 1) 1.00 0.97 0.11 Cu.sub.2−xS nanoparticles (Example 1) 1.00 0.75 0.09 Cu.sub.2−xS@Cu.sub.2−yO nanoparticles synthesized 1.00 0.82 0.27 from Cu.sub.2−xS nanoparticles (Example 2) CuS@Cu.sub.2−yO nanoparticles synthesized from 1.00 0.92 0.53 CuS nanoparticles (Comparative Example 1)

[0052] As is apparent from Table 1, compared to CuS manufactured in Preparation Example 1, in the copper sulfide of Example 1, obtained by reducing CuS, the ratio of Cu to S was lowered, and in the copper sulfide of Example 2, obtained through oxidation, the ratio of Cu to S was increased, and the O ratio was also increased, based on which it was confirmed that copper sulfide nanoparticles having a Cu.sub.2-xS@Cu.sub.2-yO core-shell structure were ultimately manufactured by reducing the CuS nanoparticles into Cu.sub.2-xS, followed by oxidation.

[0053] In Comparative Example 1, in which CuS nanoparticles were not reduced but were only oxidized, the O ratio was increased, based on which it was confirmed that copper sulfide nanoparticles having a CuS@Cu.sub.2-yO core-shell structure were manufactured.

Test Example 1. Transmittance and Stability of Copper Sulfide Nanoparticles

[0054] Preparation of Nanoparticle Suspension

[0055] 10 g of the copper sulfide nanoparticle powder manufactured in each of Preparation Example 1, Example 1, Example 2, and Comparative Example 1, 10 g of DISPERBYK-116, 80 g of methyl isobutyl ketone (MIBK), and 50 g of zirconia balls (500 μm) were added and dispersed for 14 days using a ball-mill disperser. Thereafter, zirconia balls and foreign substances were removed using a PP filter (300 mesh), thereby manufacturing a nanoparticle suspension. In addition, the size distribution of the copper sulfide nanoparticles was confirmed using a nanoparticle size analyzer (Zetasizer, Nano ZS90).

[0056] Preparation of Nanoparticle Coating Solution

[0057] 23.9 g of dipentaerythritol hexaacrylate (DPHA), 4.7 g of isobornyl (meth)acrylate (IBOA), 60.9 g of pentaerythritol triacrylate (PEPTA), and 5.5 g of 1-hydroxycyclohexylphenylketone were placed in a 250 ml flask and stirred for 1 hour using a motor stirrer, thereby preparing a binder. The binder thus prepared and the nanoparticle suspension prepared above were mixed at a weight ratio of 1:2. Thereafter, a coating solution including the nanoparticles was manufactured through stirring for 30 minutes using a stirrer.

[0058] Manufacture of Film Including Nanoparticles

[0059] The nanoparticle coating solution was applied on a PET film (SKC V7610, 100 μm) using a #5 MAYER bar. Thereafter, drying was performed for 2 minutes in a convection oven at 80° C., followed by irradiation with UV light at an intensity of 400 mJ/cm.sup.2, thus manufacturing a film including nanoparticles, of which properties such as visible-light transmittance (VLT), infrared cut (IRC), and haze were then evaluated. In order to evaluate the stability of the manufactured nanoparticles, the nanoparticles were stored for 100 hours in a thermo-hygrostat chamber (temperature: 85° C., relative humidity: 85%) and then evaluated again. The results thereof are shown in Table 2 below and in FIG. 3.

TABLE-US-00002 TABLE 2 Initial properties and properties after storage under constant-temperature and constant-humidity conditions of film including nanoparticles Initial After 100 hours under constant-temperature properties and constant-humidity conditions VLT IRC Haze VLT IRC Haze (%) (%) (%) (%) (%) (%) Preparation 58.78 70.57 1.95 67.09 32.28 18.94 Example 1 Example 1 58.70 72.00 4.69 58.63 72.19 5.35 Example 2 59.28 74.34 2.70 58.99 74.51 5.37 Comparative 67.40 44.07 5.13 68.01 30.40 21.46 Example 1

[0060] <Evaluation of Properties>

[0061] (1) VLT (visible-light transmittance): Using a UV-Vis-NIR spectrometer (Jasco, V670) for the coated film, the average value of the transmittance in the wavelength range of 380 to 780 nm was calculated to determine visible-light transmittance (%).

[0062] (2) IRC (infrared cut): Using a UV-Vis-NIR spectrometer (Jasco, V670) for the coated film, the average value of the transmittance in the wavelength range of 780 to 2,500 nm was calculated to determine infrared transmittance (%), after which the infrared cut (%) was obtained by subtracting the infrared transmittance from 100(%).

[0063] (3) Haze: The coated film was measured using a haze meter (NDK, NDH-2000N).

[0064] As is apparent from the results of Table 2, the film using the nanoparticles of Comparative Example 1 exhibited the highest visible-light transmittance but a very low near-infrared blocking effect. In Example 2, in which the CuS nanoparticles were reduced and oxidized, the visible-light transmittance was increased, and in particular, the near-infrared cut was the highest, namely 74.34%.

[0065] Based on the results of evaluation of stability under constant-temperature and constant-humidity conditions, the film using the CuS nanoparticles of Preparation Example 1 and the film using the CuS@Cu.sub.2-yO nanoparticles obtained through oxidation of Comparative Example 1 exhibited increased visible-light transmittance, but were remarkably decreased in near-infrared blocking effect. In contrast, the reduced Cu.sub.2-xS and Cu.sub.2-xS@Cu.sub.2-yO had almost no change in the visible-light transmittance, but the near-infrared cut thereof was increased. Briefly, when Cu.sub.2-xS was formed by reducing CuS, water resistance under conditions of constant temperature and constant humidity was increased and stability in water was ultimately increased.

[0066] In particular, it is possible to obtain copper sulfide nanoparticles having a core-shell structure, which are capable of exhibiting improved stability in water while maintaining the superior visible-light transmittance and infrared cut of existing copper sulfide nanoparticles, by forming a dense copper oxide film through the process of converting the surface of Cu.sub.2-xS into copper oxide. Although the visible-light transmittance and the near-infrared cut vary depending on the amount of copper sulfide nanoparticles in the film and the coating thickness, the film using Cu.sub.2-xS@Cu.sub.2-yO manufactured in Example 2 can be confirmed to exhibit a maximum visible-light transmittance of 59.28% and a maximum near-infrared cut of 74.34%. Moreover, the Cu.sub.2-xS@Cu.sub.2-yO nanoparticles had superior stability in water and thus exhibited a maximum visible-light transmittance of 58.99% and a maximum near-infrared cut of 74.51% even after 100 hours under constant-temperature and constant-humidity conditions, which are regarded as almost the same level of visible-light transmittance and near-infrared cut as before the constant-temperature and constant-humidity test.

[0067] As described hereinbefore, the present disclosure has been described in connection with specified items and predetermined embodiments and drawings, which are merely set forth to provide a better understanding of the present disclosure, and the present disclosure is not limited to the above embodiments, based on which various changes and modifications are possible, as will be apparent to those skilled in the art. Accordingly, the spirit of the present disclosure should not be confined to the disclosed embodiments, but should be defined by all modifications or modified forms derived from the accompanying claims and equivalents thereto.