KR20150126573A - Silica coated zinc oxide-polymer resin matrix and use thereof - Google Patents

Abstract

The present invention is a silica-coated zinc oxide nanoparticle preparing method, a silica-coated zinc oxide-polymer resin matrix preparing method using the same, and a use thereof. More specifically, the silica-coated zinc oxide nanoparticle preparing method can be used to adjust the thickness of the silica coating. The present invention can coat the surface of coated zinc oxide nanoparticles with silica at an appropriate thickness to prevent the photocorrosion of the nanoparticles while exhibiting an excellent photocatalytic activity inhibitory effect. According to the present invention, the silica-coated zinc oxide nanoparticles can exhibit a visible light transmission function as well as an excellent UV absorbing function. The silica-coated nanoparticles can be fused and mixed with a polymer resin to significantly increase the dispersion rate of the nanoparticles and block the pores on the silica-coated surface of the nanoparticles, thereby preventing the nanoparticles from being decomposed by an acid.

Description

[0001] SILICA COATED ZINC OXIDE-POLYMER RESIN MATRIX AND USE THEREOF [0002]

The present invention relates to a silica-coated zinc oxide-polymer resin matrix and its use, and more particularly to a silica-coated zinc oxide-polymer resin matrix using silica-coated zinc oxide nanoparticles whose silica coating thickness is controlled, Lt; / RTI >

Global warming and other factors are increasing the level of ultraviolet radiation on the Earth's surface. Ultraviolet rays have harmful effects on human skin. When exposed to ultraviolet light for a long time, polymers such as high-performance fabrics lose strength and deteriorate in quality. High-energy ultraviolet rays generate active oxygen by homolytic bond cleavage, which degrades the performance and decomposes the polymer into monomers at a rapid rate. Polymer degradation can be prevented by mixing the polymer with a suitable ultraviolet absorbing material. These materials can act as a way to quench the free radicals produced, or to reflect, disperse or absorb high energy ultraviolet radiation. By filling zinc oxide nanoparticles as an ultraviolet screening agent, polymers and fabrics can be protected.

Nano-sized ultrafine zinc oxide particles with high transparency serve as blocking agents for a wide range of UV wavelengths. Zinc oxide, an inorganic material, performs important functions in the optoelectronics, photonics and textile industries. Nanostructured oxide nanoparticles can be used for solar cells, diodes, conduction films, catalysts, gas sensors, photoluminescent devices, antimicrobial agents, wound dressings, cell labeling, UV Blocking agents and the like. On the other hand, due to their high surface energy and large surface area, zinc oxide nanoparticles tend to agglomerate easily. Therefore, the surface of the bare zinc oxide needs to be modified for better dispersion. At the same time, the photocatalytic activity of zinc oxide nanoparticles needs to be reduced to make them safer UV absorbers.

Korean Patent Publication No. 10-2010-0008690

The present invention provides a silica-coated zinc oxide-polymer resin matrix using silica-coated zinc oxide nanoparticles having excellent light stability and uses thereof.

The method for preparing silica coated zinc oxide nanoparticles comprises mixing water, an organic solvent and a catalyst (step a); Adding a zinc oxide nanoparticle and a silicate to the mixture to perform a sol-gel process comprising ultrasonication and separating the solid material by centrifugation (step b); And drying the solid to produce silica-coated zinc oxide nanoparticles (step c). The method may adjust the thickness of the silica coating by adjusting the addition amount of the silicate on the basis of the amount of the zinc oxide nanoparticles added. That is, the thickness of the silica coating can be controlled by adjusting the amount of the silicate added to a certain amount of the zinc oxide nanoparticles.

The organic solvent may include at least one selected from the group consisting of ethanol, methanol, propanol, butanol, ethyl acetate, chloroform, and hexane.

The catalyst may be ammonium hydroxide.

The silicate may be tetraethyl orthosilicate.

The step (b) may be a step of sonicating at 10 to 30 ° C for 5 to 30 minutes and centrifuging at 4000 to 6000 rpm. The drying of the step c may be carried out at 50 to 80 ° C for 10 to 24 hours.

The zinc oxide nanoparticles and the silicate may be mixed in a weight ratio of 10: 1 to 10. More preferably in a weight ratio of 10: 7 to 9. When mixed in the above range, a silica coating having the most appropriate thickness, which is excellent in light stability, can be obtained.

The polymeric resin may be poly (ethylene-co-acrylic acid).

1, zinc oxide nanoparticles can be coated with silica by TEOS through hydrolysis and subsequent condensation in the presence of NH ₄ OH. In this sol-gel process, TEOS acts as a precursor and NH ₄ OH can act as a catalyst. The surface of the zinc oxide nanoparticles can be coated with a layer of OH, and when TEOS is added to the nanoparticle mixture, the silane material can begin hydrolysis to form ZnO-Si-OH bonds at the surface of the nanoparticles. In addition, OH groups left on the outer surface can cause side-to-side polymerization. A silica shell surrounding the nanoparticles may be formed over a period of 12 hours to 24 hours.

According to the present invention, there is provided a method of preparing a zinc oxide nanoparticle, comprising: preparing a silica-coated zinc oxide nanoparticle preparation by the method; And a step of melt-mixing the silica-coated zinc oxide nanoparticles with a polymer resin to prepare a molten mixture and extrusion molding the silica-coated zinc oxide-polymer resin matrix.

The silica-coated zinc oxide nanoparticles may be 1 to 10 wt%, and more preferably 2 to 5 wt%, based on the total weight of the molten mixture.

If zinc oxide nanoparticles are not present or lower or higher wt% nanoparticles are used, the UV system can damage the entire system and cause undesirable results.

The melt mixing may be carried out at a temperature of from 150 to 200 DEG C at a screw speed of from 150 to 250 rpm. When the melt mixing is performed in the above range, the zinc oxide nanoparticles can be uniformly and highly dispersed on the polymer resin.

According to the present invention, there is also provided a silica-coated zinc oxide nanoparticle produced by the above method, wherein the surface of the zinc oxide nanoparticle is provided with silica-coated nanoparticles. The thickness of the coating may be between 6 and 8 nm. When the silica coating has the above-mentioned range of thickness, excellent light stability can be exhibited.

The silica-coated zinc oxide nanoparticles may be used for ultraviolet light shielding.

In addition, according to the present invention, there is provided a zinc oxide nanoparticle comprising silica-coated zinc oxide nanoparticles and a polymer resin, wherein the surface of the zinc oxide nanoparticles is coated with silica, and the silica nanoparticles are uniformly distributed throughout the polymer resin Zinc oxide-polymer resin matrix.

The silica-coated zinc oxide may be a silica coating having a thickness of 6 to 8 nm. When the silica coating has the above-mentioned range of thickness, excellent light stability can be exhibited.

The silica-coated zinc oxide content may be 1 to 10 wt%, more preferably 2 to 5 wt%, based on the total weight of the silica-coated zinc oxide-polymer resin matrix. If nanoparticles are absent or lower or higher wt% nanoparticles are used, UV irradiation can damage the entire system and cause undesirable results.

The silica-coated zinc oxide-polymer resin matrix may be used as a composition for blocking ultraviolet rays.

Also, according to the present invention, it is possible to provide a UV-blocking composition comprising the silica-coated zinc oxide-polymer resin matrix prepared by the above method.

According to the present invention, it is possible to prevent photocorrosion of nanoparticles and to exhibit an excellent photocatalytic activity inhibiting effect by coating the surface of zinc oxide nanoparticles with an appropriate thickness of silica.

In addition, the silica-coated zinc oxide nanoparticles according to the present invention can exhibit not only excellent UV shielding function but also visible light transmission function.

According to the present invention, the dispersion ratio of the nanoparticles can be remarkably increased by melt-mixing the polymer resin into the silica-coated nanoparticles, and the pores present on the silica-coated surface of the nanoparticles can be blocked, Can be prevented from being degraded.

Figure 1 is a schematic view of a sol-gel process involving silica coating of zinc oxide nanoparticles.
FIG. 2 shows FT-IR spectra analysis results of (a) Comparative Example 1 (bare ZnO nanoparticles) and (b) Example 1 (thin Si-ZnO nanoparticles).
FIG. 3 shows HR-TEM images of (A) Comparative Example 1 (bare ZnO nanoparticles), (B) Example 1 (thin Si-ZnO nanoparticles) and (C) Example 2 The results of the analysis are the EDX analysis results of (D) Comparative Example 1 (bare ZnO nanoparticles), (E) Example 1 (thin Si-ZnO nanoparticles) and (F) Example 2 .
FIG. 4 shows the PL intensity analysis results of Comparative Example 1 (bare ZnO nanoparticles), Example 1 (thin Si-ZnO nanoparticles), and Example 2 (thick Si-ZnO nanoparticles).
5 shows the results of analysis of methylene blue decomposition degree of Comparative Example 1 (bare ZnO nanoparticles), Example 1 (thin Si-ZnO nanoparticles) and Example 2 (thick Si-ZnO nanoparticles).
6 shows the UV-Vis absorption spectrum analysis results of Comparative Examples 1 (Z1 to Z4) and Example 2 (SZ1 to SZ4).
FIG. 7 is a schematic view showing a synthesis process of a silica-coated zinc oxide nanoparticle-polymer resin matrix according to an embodiment of the present invention.
Fig. 8 shows the FE-SEM image analysis results of (A) Comparative Example 2 (PEAA resin), (B) Comparative Example 3 (bare ZnO / PEAA) and (C) Example 3 (thick Si- ZnO / PEAA) (I) Comparative Example 2, (ii) Comparative Example 3, and (iii) EDX spectral analysis results of Example 3.
9 is a graph showing the results of (a) Comparative Example 1 (bare ZnO nanoparticles), (b) Example 1 (thin Si-ZnO nanoparticles) ) Comparative Example 3 (bare ZnO / PEAA), (c) UV-Vis transmission spectral analysis of Example 3 (thick Si-ZnO / PEAA).

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. The scope of the present invention is defined by the appended claims and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

Example 1: Preparation of silica-coated zinc oxide nanoparticles (thin Si-ZnO nanoparticles)

(30 wt% in ethanol, Advanced Nano Particles Co., Ltd.), tetraethylorthosilicate (TEOS, 99.999%, Sigma-Aldrich, USA), ethanol (99.9% (NH ₄ OH, 25-28%, DC Chemical, Korea), acetic acid (99.5%, Samcheon Chemical, Korea), poly (ethylene-co- acrylic acid) (PEAA resin, Dow Chemical) wt% solution in water, Sigma-Aldrich USA).

Silica - coated ZnO nanoparticles were synthesized by sol - gel process as follows. Ethanol 35 ㎖, 15 ㎖ water and _{NH 4 OH 10 ㎖ (pH 12} ) was stirred in 100 ㎖ round bottom flask. 0.5 g of ZnO dispersion and an appropriate amount of TEOS (weight ratio of ZnO to TEOS of 10: 3) were injected into the reaction flask. After sonication for 10 minutes, the colloidal dispersion was stirred for 12 hours for complete hydrolysis of TEOS. The solids were then recovered by centrifugation at 5,000 rpm (Sigma, 2-6PK), washed successively three times with ethanol and then dried in a vacuum oven at 60 占 폚 for 12 hours to obtain a 2 nm thick silica coated zinc oxide nano (Thin Si-ZnO nanoparticles) were prepared.

Example 2: Manufacture of silica-coated zinc oxide nanoparticles (thick Si-ZnO nanoparticles)

The remaining conditions were the same as above and zinc oxide (thick Si-ZnO nanoparticle) having a silica coating formed with a thickness of 7 nm was prepared by varying the amount of TEOS (weight ratio of ZnO and TEOS to 10: 8).

Example  3: Silica coated zinc oxide-polymer resin matrix ( thick Si - ZnO / PEAA  Matrix) manufacturing

PEAA resin was used as the polymer resin. The acrylic acid content of the PEAA resin was about 20% by weight. First, the PEAA resin pellets and the powder of the thick-Si-ZnO nanoparticles according to Example 2 were mixed. The content of the nanoparticles according to Example 2 was set at 3 wt% based on the total mixture. Then melt-blended at 180 DEG C at a screw speed of 200 rpm and extruded using a twin-screw extruder (Bautek Co., ba-11). These pellets were formed into a film (thick Si-ZnO / PEAA matrix) in the form of a film having a thickness of 1 mm at a temperature of 180 ° C and a pressure of 600 kg / cm ² using a press machine (Seijin Technology Co., Ltd.). The sample was cut into liquid nitrogen and used for analysis.

Comparative Example  One

Zinc oxide nanoparticles (bare ZnO nanoparticles) were prepared by drying a solution of ZnO (30 wt% in ethanol, Advanced Nano Particles Co., Ltd.) in a vacuum oven at 60 캜 for 12 hours

Comparative Example  2

A matrix (PEAA resin matrix) was formed by the same method using the same resin pellets as used in Example 3 (zinc oxide nanoparticles were not added).

Comparative Example  3

In addition to the nanoparticles (thick Si-ZnO nanoparticles) according to Example 2, nanoparticles according to Comparative Example 1 were used, and other conditions were the same as Example 3 except that bare ZnO / PEAA Matrix)

Experimental Example  One: FT - IR ( Fourier transform infrared ) Spectra analysis

(Bruker, IFS-66 / S) to (a) Comparative Example 1 (bare ZnO nanoparticles) and (b) Example 1 (thin Si- ZnO nanoparticles) Respectively. The peaks at 1,550 to 1,700 cm ^-1 and 3,100 to 3,600 cm ^-1 can be attributed to the hydroxyl groups of water. ~ Si-O-Si asymmetric 980 stretching vibration band of 1,190cm ^-1 was found only in the spectrum of Example 1 (b). Si-ZnO bond formation was confirmed by a decrease in peak intensity at 700-750 cm < ^-1 > associated with Si-O-Si. This demonstrates the presence of the silica layer and that the silica layer has been successfully coated onto the zinc oxide nanoparticles.

Experimental Example  2: HR - TEM  image, EDX  And zeta potential analysis

HR-TEM images of (A) Comparative Example 1 (bare ZnO nanoparticles), (B) Example 1 (thin Si-ZnO nanoparticles) and (C) Example 2 ray spectrometer (Tecnai G2 TF 30ST). The results are shown in FIG. A ZnO core surrounded by a distinctive silica coating (indicated by the arrow) is clearly visible. A thin layer of silica coating was observed in Figure 3 (B). The nanoparticles are non-uniformly covered with a thickness of 2 nm. Fig. 3 (C) shows a thick, uniform silica layer. 7 nm thick, which is due to the high concentration of silicate. The silica layer formed on the ZnO nanoparticles was further analyzed by EDX and zeta potential measurements. (D) Comparative Example 1 (pure ZnO nanoparticles), (E) Example 1 (thin Si-ZnO nanoparticles), (F) Thick Si-ZnO nanoparticles were subjected to EDX analysis (Tecnai G2 TF 30ST) 3 (D, E and F). This reflects the chemical composition of the core and silica shell, including Zn, O and Si. Table 1 shows the results of elemental quantitative analysis of the nanoparticles. In the EDX analysis, 0.02 wt% of silica was observed in thin Si-ZnO nanoparticles whereas 0.19 wt% of silica was observed in thick Si-ZnO nanoparticles. This weight difference is due to the difference in silica thickness comprised between 2 nm and 7 nm. The silica quantitative peaks in Figures 3 (E) and 3 (F) agreed well with the TEM image (see Figures 3 (B) and 3 (C)).

Sample Comparative Example 1 Example 1 Example 2 Element Weight% Atomic% Weight% Atomic% Weight% Atomic% C (K) 41.81 65.56 19.32 40.12 40.87 65.55 O (K) 19.58 23.05 24.71 38.52 18.63 22.43 Si (K) 0.00 0.00 0.02 0.02 0.19 0.13 Zn (K) 38.61 11.38 55.93 21.33 40.29 11.87

Zeta potential analysis (Malvern Zeta-Sizer 3000HS) was performed for electrokinetic analysis at pH 7. Comparative Example 1 showed a value of + 31.0 mV. Example 1 showed -23.7 mV and Example 2 showed -43.6 mV. The high negative zeta potential of Example 2 is due to the bulk silica layer containing a large number of Si-OH groups on the surface.

When light is irradiated on the surface of a semiconductor (ZnO) having photocatalytic activity, the binding energy becomes weaker, so that electron-hole pairs diffuse to the surface. These electrons and holes interact with the surrounding oxygen or water to produce a free radical with strong oxidizing ability. This decomposes organic compounds such as dyes and polymers (J. Yao, C. X. Wang, Int. J. Photo. 643182 (2010) 1-6.). In addition, photocorrosion of the semiconductor nanoparticles increases the energy gap causing photoetching of the particles and causes agglomeration to form larger particles (T. Torimoto, JP Reyes, K. Iwasaki, B. Pal , T. Shibayama, K. Sugawara, H. Takahashi, B. Ohtani, J. Am. Chem. Soc. 125 (2003) 316-7.). In consideration of this fact, in order to prevent photocorrosion of ZnO nanoparticles, the surface of the nanoparticles is coated with silica.

Experimental Example 3: PL intensity analysis

The PL reaction of the nanoparticles after UV irradiation was analyzed and shown in FIG. The extent of photodegradation was measured indirectly by measuring the change in PL intensity using a spectrofluorometer (Varian Cary Eclipse). (Bare ZnO nanoparticles), Example 1 (thin Si-ZnO nanoparticles) and Example 2 (thick Si-ZnO nanoparticles) were irradiated with UV light (CN-6 UV lamp, 365 nm 60 HZ), and the respective PL intensity responses were recorded every 4 hours.

As time elapsed, Comparative Example 1 showed low light stability for light irradiation. PL decreased to 80% after 72 hours. In contrast, Example 2 showed only a 5% decrease after the entire exposure time. Meanwhile, Example 1 showed a reduction rate of about 50% lower than that of Comparative Example 1 during the entire exposure time, but showed a higher reduction rate than Example 2. This is due to the rather thin silica layer to prevent photocorrosion. This is because the thick silica shell covering the ZnO nanoparticles prevents excited electrons associated with free radical generation or photoetching after monochromatic light exposure. Compared to silica coated ZnO nanoparticles, uncoated particles are easily attacked by strong light and become unstable by photoetching. This is due to the fact that the optical stability of the semiconducting nanoparticles is reduced due to energy gap-type surface defects due to high-energy irradiation.

Experimental Example 4: Photolysis analysis of MB (methylene blue)

To evaluate the photodegradation mechanism of Comparative Example 1 (bare ZnO nanoparticles), Example 1 (thin Si-ZnO nanoparticles) and Example 2 (thick Si-ZnO nanoparticles) for water-soluble MB solution, a photocatalyst Particles) were dispersed in MB aqueous solution and stirred for 30 minutes in a dark environment to achieve complete physical adsorption equilibrium. The reaction mixture was then irradiated with UV light for up to 180 minutes for photodecomposition studies. Then, at regular intervals, samples taken from the reaction vessel were quickly centrifuged to avoid particle interference. The supernatant was determined by UV-VIS spectroscopy (Varian Inc., Cary 5000) at 664.1 nm. Absorbance was measured and plotted as a function of time. The degree of MB decomposition is expressed by the following equation [R. Wang, J.H. Xin, Y. Yang, H. Liu, L. Xu, J. Hu, Appl. Surf. Sci. 227 (2004) 312-317.]:

Remaining MB (%) = (A ₀ -A / A ₀ ) × 100%

(A ₀ = initial absorbance, A = variable absorbance).

In Fig. 5, the relationship between the change in MB residual amount and the irradiation time is shown. In each of Examples 1 and 2, MB degradation of 55% and 12% was observed. This result implies that silica-coated nanoparticles reduce photodegradation. When ultraviolet light is irradiated on the non-silica-coated nanoparticles, electron / hole migration or formation of oxygen-active species occurs on the surface, which quickly breaks the MB from blue to colorless. Example 1 improved significant light stability, but MB decomposition also increased as UV irradiation time increased. This is due to an uneven silica layer.

Example 2 in which the ratio of TEOS to ZnO was increased to form a silica shell with a thickness of 7 nm showed an excellent photocatalytic activity inhibiting effect and was attributed to the chafing effect of the silica layer uniformly formed on the surface of the ZnO nanoparticles . The SiO ₂ layer acts as a barrier to prevent the movement of electrons / holes generated in ZnO on the surface. Therefore, zinc oxide nanoparticles having a silica shell thicker than a thin silica shell may exhibit photodegradation-inhibiting properties, that is, light stability. In addition, the silica-coated zinc oxide nanoparticles according to an embodiment of the present invention exhibit not only excellent UV absorption but also visible light transmission function.

FIG. 6 shows UV-VIS absorption spectral analysis (Varian Inc., Cary 5000) of Comparative Example 1 (bare ZnO nanoparticles) and Example 2 (thick Si-ZnO nanoparticles). Different concentrations of aqueous acetic acid were used as the acid solution medium. To 100 ml of pure water was added acetic acid with a suspension of Comparative Example 1 (bare ZnO nanoparticles) and Example 2 (thick Si-ZnO nanoparticles), respectively. After stirring for 30 minutes, the sample was analyzed by UV-VIS spectroscopy. The concentration of the nanoparticles was kept constant and UV-VIS absorption was measured according to acetic acid concentration (see Table 2). In the case of Comparative Example 1, an absorption peak was exhibited at 370 nm. The initial absorbance intensity was highest in the absence of acetic acid. However, the absorbance intensity of the nanoparticles (Z2 to Z4) according to Comparative Example 1 decreased with increasing acetic acid concentration. This indicates that the dissolution of ZnO was completely performed by the acid. An aqueous solution of acetic acid transforms ZnO into a zinc acetate complex, which does not absorb UV light. No absorption peak was observed at the highest acetic acid concentration. The absorbance of the ZnO nanoparticles (SZ1 - SZ4) according to Example 2 showed a tendency to decrease in absorbance intensity similar to that of the nanoparticles according to Comparative Example 1. The silica coating formed on ZnO has many micro- and mesopores, and these pores allow direct contact with acids on the surface of ZnO. High-concentration water-soluble acetic acid dissolves all ZnO regardless of whether the silica layer is thick or thin.

Sample code Acetic acid Comparative Example 1
(Bare ZnO nanoparticles) Sample code Acetic acid Example 2
(Thick Si-ZnO nanoparticles) Z1 None 0.002 mol
(0.163 g) SZ1 None 0.002 mol
(0.203 g) Z2 0.002 mol
(0.120 g) 0.002 mol
(0.163 g) SZ2 0.002 mol
(0.120 g) 0.002 mol
(0.203 g) Z3 0.003 mol
(0.180 g) 0.002 mol
(0.163 g) SZ3 0.003 mol
(0.180 g) 0.002 mol
(0.203 g) Z4 0.004 mol
(0.240 g) 0.002 mol
(0.163 g) SZ4 0.004 mol
(0.240 g) 0.002 mol
(0.203 g)

Experimental Example 5: UV Shielding Effect

By measuring the transmission spectrum of the film, the UV shielding properties of nanoparticles and PEAA incorporated nanoparticles were compared. The melt-blended nanoparticles / PEAA matrix (see FIG. 7) was cut into thin films of the required size and further analyzed by the UV-VIS spectrophotometer FE-SEM-EDX. 8 shows an FE-SEM image of (A) Comparative Example 2 (PEAA resin), (B) Comparative Example 3 (bare ZnO / PEAA matrix) and (C) Example 3 (thick Si-ZnO / PEAA matrix) . Comparative Example 2 exhibited a flat, smooth surface with no particles. In Comparative Example 3, bare ZnO nanoparticles observed as agglomerates were unevenly attached to the resin. In the case of Example 3, silica-coated ZnO nanoparticles were uniformly distributed on the entire surface of the resin. This was easily distinguished by the bright spots found on the resin surface due to the higher atomic weight of the nanoparticles due to photon excitation. It has been determined that the complete high dispersion of silica-coated ZnO nanoparticles by the melt mixing process produced a more efficient shading polymer matrix.

ZnO coated with melt-mixed silica is inserted into the PEAA resin layer. At this time, incomplete bonding of the silica layer on the surface of the OH group and silica coated ZnO results in weak interaction with the carbonyl group of PEAA to form a solid-metal complex . Basically, the silica particles are not easily decomposed by weak acids such as acrylic. However, the results of FIG. 6 above showed that the silica-coated ZnO nanoparticles were completely decomposed by acetic acid. This is because the acid directly contacts the surface of ZnO through the micro- and mesopores present in the silica layer. However, since ZnO can not be in direct contact with the acid group of PEAA because such pores are blocked during melt mixing of PEAA and silica coated ZnO nanoparticles, ) Exhibited strong stability against acid decomposition as compared with Comparative Example 3 (bare ZnO / PEAA).

8 (i, ii, iii) are the EDX analysis results. The elemental spectrum showed the presence of Zn in Comparative Example 3 (ZnO / PEAA matrix) and the presence of Zn and Si in Example 3 (Si-ZnO / PEAA matrix). In Comparative Example 2 (PEAA resin), nothing was confirmed (C and O are derived from the supporting substrate).

FIG. 9 is a graph showing the results of (a) Comparative Example 1 (bare ZnO nanoparticles), (b) Example 2 (thick Si-ZnO nanoparticles) and (ii) Comparative Example 2 (PEAA resin matrix) b) Comparative Example 3 (bare ZnO / PEAA matrix), and (c) Example 3 (Si-ZnO / PEAA matrix). As shown in Fig. 9, Comparative Example 2 (PEAA resin matrix) exhibited the highest transmittance to light. In the case of Comparative Example 3, about 96% of ultraviolet light was transmitted through the nanoparticle resin matrix. Zinc oxide exhibited excellent ultraviolet shielding effect when present alone, but Comparative Examples 2 and 3 showed high transmittance. As a result, zinc oxide was decomposed by an acid group present in the PEAA resin present in the PEAA resin . In the case of Example 3, the ultraviolet shielding property was about 97%. At 380 nm and below, the transmittance was lower than that of semiconductor nanocrystals (ZnO). Where the absorption edge of the semiconductor nanocrystals is related to the bandgap.

In the visible region, Example 3 (Si-ZnO / PEAA matrix) showed a transmittance reduced by about 50% at 800 nm compared to Comparative Example 3 (bare ZnO / PEAA matrix). This is based on the ZnO core size. The smaller the size, the better the visible light transmittance and the superior ultraviolet shielding effect. Example 3 (thick Si-ZnO / PEAA matrix) showed a transmission spectrum similar to that of Example 2 (thick Si-ZnO nanoparticles). Example 3 shows that even though the PEAA resin was added, Shielding properties. These results indicate that the increase of the thickness of the silica layer surrounding the zinc oxide nanoparticles prevents the decomposition of PEAA resin by ultraviolet rays and prevents the acid dissolution of zinc oxide by PEAA. As described above, since the silica-coated zinc oxide-PEAA matrix (see Example 3) by the melt mixing process significantly improves ultraviolet shielding property, it is used for producing ultraviolet shielding fibers using nylon 4 or the like .

Claims (5)

A silica-coated zinc oxide-polymer resin matrix having zinc oxide nanoparticles in which silica is coated on the surface of particles is uniformly distributed throughout the polymer resin,
Wherein the polymer resin is poly (ethylene-co-acrylic acid)
Characterized in that it has a structure in which the pores of the silica layer coated on the surface of the nanoparticles are blocked by a melt mixing method.
Silica coated zinc oxide - polymeric resin matrix.
The method according to claim 1,
Wherein the silica-coated zinc oxide is formed with the silica coating having a thickness of 6 to 8 nm.
The method according to claim 1,
Wherein the zinc oxide-coated silica-coated zinc oxide-polymeric resin matrix is 2-5 wt% based on the total weight of the silica-coated zinc oxide-polymeric resin matrix.
The method according to any one of claims 1 to 3,
Wherein the silica-coated zinc oxide-polymer resin matrix is used as an ultraviolet-shielding composition.
A composition for ultraviolet protection comprising the silica-coated zinc oxide-polymer resin matrix of claim 4.

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