WO2009051443A2

WO2009051443A2 - Photoactive composition comprising scoria and preparation method thereof

Info

Publication number: WO2009051443A2
Application number: PCT/KR2008/006152
Authority: WO
Inventors: Se Jong Koh; Seung Hyeop Kwon
Original assignee: NURIDLE CO Ltd
Current assignee: NURIDLE CO Ltd
Priority date: 2007-10-19
Filing date: 2008-10-17
Publication date: 2009-04-23
Anticipated expiration: 2010-04-19
Also published as: KR20090040066A; WO2009051443A3; KR100941738B1

Abstract

Disclosed is a photoactive composition including 0.1-40 wt % of a photocatalyst in a powder or solution phase or a photocatalyst made of metal alkoxide; and 0.1-30 wt % of scoria powder, with the balance being a solvent, and a preparation method thereof. When interior coating is performed using the photoactive composition, activity can be exhibited even without the additional irradiation of light, and an organic material can be adsorbed and decomposed at high efficiency using only a very low light source through the combination of the adsorption performance of scoria and the decomposition performance of a photocatalyst. Because the photoactive composition is not in a powder phase but is in a liquid colloidal state, it can be efficiently employed as a coating agent enabling the surface coating treatment of any material and as an additive which is introduced into the preparation process of industrial materials or processed products.

Description

PHOTOACTIVE COMPOSITION COMPRISING SCORIA AND PREPARATION METHOD THEREOF

Technical Field

[1] The present invention relates to a photoactive composition containing scoria powder, which can exhibit activity using only an interior light source without the additional irradiation of light and can adsorb and decompose an organic material at high efficiency even using only the very low light source through the combination of the adsorption performance of scoria and the decomposition performance of a photocatalyst, and to a preparation method thereof. Background Art

[2] Scoria, which is a volcanic rock distributed over the whole region of Jeju island, is mainly composed of SiOl-AllOS-FelCβ-MgO-CaO-NalO-TiOl, and development of various commercial products using scoria and research into utilizing the properties of scoria has been conducted.

[3] In particular, the 4 wt% titanium dioxide (TiO2) contained in scoria and a porous structure thereof enable the absorption and decomposition of an organic material.

[4] The applicative fields of scoria which have been at present commercialized generally include cosmetic products or fiber applications using natural minerals contained in scoria or the porous structure thereof.

[5] Also, a photocatalyst is a catalyst that accelerates a chemical reaction using light.

Particularly useful in the industrial field, titanium dioxide decomposes harmful materials or exhibits the ability to purify the atmosphere and water, deodorization, disinfecting and antifouling functions, and also, has super-hydrophilic properties and thus manifests a self -purification function of a surface of a substrate.

[6] In the case of pure titanium dioxide, it shows excellent photocatalytic activity under

UV light at a wavelength of 380 nm or less but has insignificant activity under visible light at 400 nm or longer wavelength, which corresponds to most solar light.

[7] Hence, thorough research into development of photocatalysts having activity under visible light is being conducted, and includes doping of metal ions or mixing of materials having different photocatalytic properties.

[8] However, these photocatalysts require a special control process upon preparation thereof and their stability has not yet been demonstrated, compared to titanium dioxide which is known as a stable material upon exposure to the outside and to the human body. Further, methods of injecting metal ions have a very complicated process with a need for expensive materials, and are thus difficult to commercialize. [9] To date, a photoactive agent using scoria has not been developed, and natural scoria rock is applied as a building material using a processing technique. Moreover, scoria is regarded as a specialty product of Jeju island and the amount which can be taken out thereof is very limited. The current processing technique includes crushing through simple milling, and thus the resulting rock particles have a non-uniform particle size and are unable to be used to prepare a colloidal dispersion state for an application as a coating agent.

[10] Also, in the case of the photocatalyst, substances having activity in the visible range have been developed, but have problems in which the preparation process thereof is complicated and expensive materials are used, and there are questions as to whether such substances are stable in terms of chemical stability or stability in the human body. Disclosure of Invention Technical Problem

[11] Accordingly, the present invention has been made keeping in mind the above problems encountered in the related art, and provides a novel photoactive composition, in which Fe2O3 mainly contained in scoria is dissolved in a solvent upon milling, thus enabling the stable addition of Fe, thereby realizing metal ion injection effects, and also in which, upon the milling of scoria and metal alkoxide including titanium alkoxide, nano-sized anatase-type titanium dioxide may be produced, thus exhibiting activity using only an interior light source.

[12] In addition, the present invention provides a novel photoactive composition, which can exhibit activity even without the additional irradiation of light after an interior coating process has been performed and which can adsorb and decompose an organic material at high efficiency using only the very low light source through the combination of the adsorption performance of scoria and the decomposition performance of a photocatalyst.

[13] In addition, the present invention provides a novel photoactive composition, which can be prepared not in a powder phase but in a liquid colloidal state and can thus be applied on the surface of any material, and also can be easily introduced to the preparation process of industrial materials and processed products to thus be uniformly mixed therewith. Technical Solution

[14] According to the present invention, a photoactive composition includes 0.1-40 wt% of a photocatalyst in a powder or solution phase or a photocatalyst made of metal alkoxide; and 0.1-30 wt% of scoria powder, with the balance being a solvent.

[15] The metal alkoxide may include one or more selected from among any one titanium alkoxide selected from the group consisting of titanium(IV) propoxide, titanium(IV) isopropoxide, titanium(IV) diisopropoxide, titanium(IV) butoxide, titanium(IV) ethoxide and titanium(IV) methoxide; and any one zirconium alkoxide selected from the group consisting of zirconium(IV) tert-butoxide, zirconium(IV) butoxide, zirconium(rV) ethoxide, zirconium(IV) propoxide and zirconium(IV) isopropoxide.

[16] The amount of the photocatalyst derived from metal alkoxide may be set to 0.1-40 wt% and preferably 1-30 wt% based on the total solid content of the composition. If the amount thereof falls outside of the above range and exceeds 40 wt%, storage stability is reduced and a coating film appears as a white turbidity. Conversely, if the amount thereof is less than 0.1 wt%, purification and deodorization performance may be deteriorated.

[17] The amount of the scoria powder may be set to 0.1-30 wt% and preferably 0.5-20 wt% based on the total solid content of the composition. If the amount thereof falls outside of the above range and exceeds 30 wt%, dispersion stability is reduced and thus precipitation occurs. Conversely, if the amount thereof is less than 0.1 wt%, photoactive agent functionality cannot be obtained under visible light.

[18] The solvent may include one or more selected from the group consisting of water; any one alcohol selected from the group consisting of methanol, ethanol, propanol, butanol and isopropanol; any one acetone selected from among diacetone alcohol and acetyl acetone; and cellosolve selected from the group consisting of methyl cellosolve, ethyl cellosolve, butyl cellosolve and cellosolve acetate.

[19] The solvent may be added such that the total solid content is 1-30 wt%. If the solvent is used in an amount exceeding the above upper limit, the solid content is small and thus photoactive agent functionality cannot be obtained. Conversely, if the solvent is used in an amount less than the above lower limit, storage stability is reduced, a uniform coating film cannot be formed, and a white turbidity phenomenon may occur.

[20] Also, the photoactive composition according to the present invention may further include an inorganic binder for improving adhesion to a substrate and adsorption performance. The inorganic binder may be used in an amount of 100 parts by weight or less based on 100 parts by weight of the photoactive composition. If the amount thereof falls outside of the above range and is used in an excess amount, photoactive agent functionality cannot be obtained.

[21] The inorganic binder may be prepared by subjecting colloidal silica having a particle size of 5-50 nm to adjustment of pH with a solvent and an acid catalyst or a base catalyst, mixing with an organic silane compound and then reaction at a temperature ranging from room temperature to 6O⁰C for 3-6 hours.

[22] Examples of the colloidal silica may include commercially available products under the trade name of Rudox or Snowtex, and examples of the solvent may include water, an alcohol such as methanol, ethanol, propanol, butanol and isopropanol, a cellosolve such as methyl cellosolve, ethyl cellosolve, butyl cellosolve and cellosolve acetate, and an acetone such as diacetone alcohol and acetyl acetone.

[23] Examples of the organic silane compound may include methyltrimethoxy silane, methyltriethoxy silane, dimethyldimethoxy silane, dimethyldiethoxy silane, vinyltrimethoxy silane, vinyltriethoxy silane, vinylmethyldimethoxy silane, vinyl- methyldiethoxy silane, phenyltrimethoxy silane, diphenylethoxyvinyl silane, tetraethoxy silane, ethoxymethylvinyl silane, butoxytrimethyl silane, butyltrimethoxy silane, methyltriisopropoxy silane, methyltriacetoxy silane, tetraphetoxy silane, tetrapropoxy silane and vinyltriisopropoxy silane, which may be used alone or in combinations of two or more thereof.

[24] Also, the photoactive composition according to the present invention may further include a metal additive for improving antimicrobial and disinfecting functions. The metal additive may include silver (Ag), platinum (Pt) and copper (Cu), and may be used in an amount of 0.01-5 parts by weight based on 100 parts by weight of the photoactive composition.

[25] If the metal additive is used in an amount exceeding the above upper limit, a precipitation occurs due to the reaction of metal ions, undesirably causing storage stability problems. Conversely, if the metal additive is used in an amount less than the above lower limit, antimicrobial effects under visible light may be reduced.

[26] In addition, the present invention provides a method of preparing the photoactive composition, including dissolving metal alkoxide in a solvent thus preparing a pho- tocatalyst solution; mixing the photocatalyst solution with scoria powder and then performing milling, thus preparing a scoria dispersion solution; adding a solvent to the scoria dispersion solution, thus controlling a solid content of the solution; and adding an acid or a base to the solution having the controlled solid content, thus adjusting a pH of the solution.

[27] Specifically, in the preparation of the photocatalyst solution, the solvent may be mixed with an acid catalyst or a base catalyst, and, with stirring, metal alkoxide may then be added thereto, thus preparing the photocatalyst solution. As such, the acid catalyst or the base catalyst functions to adjust a reaction rate and improve the storage stability and dispersibility of a final sol. The acid catalyst or the base catalyst may be used alone or in combinations of two or more, depending on the storage stability and properties of the dispersion solution. Examples of the acid catalyst may include acetic acid, phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid, chlorosulfonic acid, para-toluenesulfonic acid, trichloroacetic acid, polyphosphoric acid, iodic acid, and iodic anhydride.

[28] Examples of the base catalyst may include caustic soda, aqueous ammonium solution, potassium hydroxide, n-butylamine, imidazole, ammonium perchlorate, trimethylamine, and triethylamine.

[29] In the preparation of the scoria dispersion solution, the prepared photocatalyst solution or anatase-type TiO2 colloidal solution or powder may be added with scoria powder, mixed with stabilized zirconia balls having a diameter of 1-10 mm, and then milled at 100-500 rpm for 4-24 hours, thus preparing the scoria dispersion solution.

[30] Examples of the anatase-type TiO2 colloidal solution or powder may include commercial available products under the trade name of ST series (Ishihara) or P-25 (Degussa), and the prepared solution may be used alone as an additive through the control of the solid content thereof.

[31] To serve as a coating agent, the prepared scoria dispersion solution may be further added with the inorganic binder. The inorganic binder may be prepared by subjecting colloidal silica having a particle size of 5-100 nm to adjustment of pH using the solvent and the acid catalyst or base catalyst, mixing with the organic silane compound, and then reaction at a temperature ranging from room temperature to 8O⁰C for 3-6 hours.

[32] In the control of the solid content, the prepared scoria dispersion solution may be added with the solvent, thus controlling the solid content.

[33] In the adjustment of the pH, the solution having the controlled solid content may be added with the acid catalyst or the base catalyst so that the pH thereof is adjusted from 1 to 14, thereby preparing a final scoria-based photoactive colloidal solution.

[34] In the method of preparing the photoactive composition according to the present invention, fining of scoria powder and production of titanium dioxide from titanium alkoxide may be simultaneously performed, thereby obtaining a solution which has nano-sized particles so that a specific surface area is maximized upon coating to thus maintain a photoactive reaction for a long period of time. Further, the scoria, which has been processed to a powder phase, may be provided in the form of a nano-sized colloidal coating solution having dispersion stability.

[35] Also, according to the present invention, using natural scoria rock, it is possible to provide the solution which is improved in terms of the metal ion injection effect and adsorption performance, includes the nano-sized anatase-type titanium dioxide easily resulting from the reaction, has superior storage stability, and has demonstrated stability in the human body, thereby enabling various applications.

Advantageous Effects

[36] According to the present invention, a photoactive composition can exhibit activity using only an interior light source through production of nano-sized anatase-type titanium dioxide resulting from the reaction of metal alkoxide including titanium alkoxide with scoria upon milling, and also can adsorb and decompose an organic material at high efficiency even using only the very low light source through the combination of the adsorption performance of scoria and the decomposition performance of a photocatalyst. The photoactive composition according to the present invention can be prepared not in a powder phase but in a liquid colloidal state and thus can be applied on the surface of any material. Also, the photoactive composition can be easily introduced to the preparation process of industrial materials and processed products to thus be uniformly mixed therewith. Therefore, the photoactive composition according to the present invention can be efficiently utilized as a coating agent and an additive for decomposition of harmful materials, purification of the atmosphere and water, deodorization, antimicrobial, antifouling, self-purification, super-hydrophilic, and far infrared radiation functions. Brief Description of the Drawings

[37] FIGS. 1 and 2 show the results of EDS of the examples of the present invention;

[38] FIG. 3 shows the results of XRD of the examples of the present invention (upper:

Example 3, lower: Example 1);

[39] FIG. 4 shows an electron micrograph of the example of the present invention;

[40] FIGS. 5 and 6 show the contact angle to water of the examples of the present invention; and

[41] FIG. 7 shows the decomposition rate of organic material by the examples of the present invention (■: Example 1; ▲: Example 2; O: Example 3; *: Example 4; ♦: Example 5). Best Mode for Carrying Out the Invention

[42] A better understanding of the present invention may be obtained through the following examples and comparative examples which are set forth to illustrate, but are not to be construed as limiting the present invention.

[43] <Example 1>

[44] Into an Erlenmeyer flask, 140 g of distilled water and 4 g of acetic acid were introduced, and, with stirring, 40 g of titanium(IV) isopropoxide and 4 g of acetyl acetone were then added thereto, after which stirring was performed until a completely clear solution was obtained.

[45] The solution thus obtained was loaded in a mill, mixed with 12 g of scoria powder and stabilized zirconia balls having a diameter of 1-10 mm and then rapidly milled at 400 rpm for 12 hours.

[46] To 30 g of the scoria dispersion solution thus milled was added 70 g of distilled water and then ammonia water, thus preparing a solution having a pH of 6.

[47] <Example 2>

[48] A solution was prepared in the same manner as in Example 1, with the exception that zirconium(IV) propoxide was used instead of titanium(IV) isopropoxide.

[49] <Example 3> [50] A solution was prepared in the same manner as in Example 1, with the exception that 44 g of distilled water was used instead of titanium(IV) isopropoxide and acetyl acetone.

[51] <Example 4> [52] A solution was prepared in the same manner as in Example 1, with the exception that anatase-type titanium dioxide photocatalyst powder having an average particle size of 10-30 nm was used instead of scoria powder.

[53] <Example 5> [54] 100 g of the dispersion solution of Example 1 was mixed with an inorganic binder, added with water to control a solid content thereof, and then added with ammonia water, thus preparing a solution having a pH of 6.

[55] As such, the inorganic binder was prepared by subjecting 10 g of colloidal silica to mixing with 35 g of distilled water, 1 g of nitric acid and 20 g of alcohol, stirring, addition of 34 g of tetraethoxy silane, reaction at 6O⁰C for 4 hours, cooling and then mixing.

[56] Experimental Example 1> Evaluation of Properties [57] 1) Component Analysis [58] The dry powder of the scoria dispersion solution of each of Examples 1 and 3 was analyzed using EDS (Energy Dispersive X-ray Spectrometer) (JSM-6500, Jeol, Japan). As a result, as shown in FIGS. 1 and 2, the Ti peak of FIG. 1 in which the amount of TiO2 was increased due to the addition of titanium alkoxide was higher than that of FIG. 2 in which only the scoria powder was dispersed. As shown in Table 1 below, the scoria dispersion solution of Example 1 had an increased amount of TiO2, and Fe2O3 mainly contained in scoria was dissolved in the solvent and thus the amount thereof was reduced.

[59] Table 1 [Table 1] [Table ]

[60] 2) X-ray Diffractive Analysis [61] The dry powder of the scoria dispersion solution of each of Examples 1 and 3 was analyzed using XRD (X-ray Diffractometer) [Cu Ka] (RINT200, Rigaku Co., Japan). As a result, as shown in FIG. 3, in Example 1, titanium alkoxide could be seen to be efficiently formed into an anatase phase through the reaction in the course of milling.

[62] 3) Microstructure Observation

[63] The scoria dispersion solution of Example 1 was applied on glass and the surface thereof was observed using SEM (JSM-6500, Jeol, Japan). As a result, as shown in FIG. 4, nano-sized particles were uniformly distributed, and high surface roughness could maximize a specific surface area in a coating process so that adsorption and decomposition performance of a harmful material could be maintained for a long period of time even using only an interior light source.

[64] 4) Measurement of Contact Angle

[65] The contact angle to water of the scoria dispersion solution of each of Examples 1 and 3 under visible light was measured in a manner such that a coating film thereof was formed and then simply dried, after which the contact angle was measured using a contact angle meter (SEO 300A, SEO Co. Ltd., Korea) under a fluorescent light without the additional irradiation of light. As a result, as shown in FIG. 5, in the case of the scoria dispersion solution of Example 1, the contact angle was measured to be 4° or less, thus exhibiting high hydrophilic properties. As shown in FIG. 6, in the case of the scoria dispersion solution of Example 3, the contact angle was measured to be 15°, resulting in relatively weak hydrophilic properties.

[66] 5) Measurement of Decomposition Rate of Organic Material (TMA)

[67] Using the scoria dispersion solution of each example, a coating film was formed and then simply dried to measure the decomposition rate of a gaseous organic material under visible light. Then, without the additional irradiation of light, the concentration of formaldehyde (HCHO) over time was measured using a gas detecting tube, and thus the deodorization rate related to the organic material decomposition was calculated using Equation 1 below.

[68] Equation 1

[69] Deodorization Rate = ((Cb-Cs)/Cb) x 100

[70] wherein Cb is the concentration of the test gas of a blank remaining in the test tube after a lapse of time, and Cs is the concentration of the test gas of a sample remaining in the test tube after a lapse of time.

[71] As shown in Table 2 below, when only the scoria powder was used, the deodorization rate was determined to be about 47% for 1 hour, and thus adsorption performance and decomposition performance were exhibited but the effects thereof were insignificant. However, according to the present invention, the photoactive composition containing scoria exhibited a relatively high deodorization rate.

[72] 6) Measurement of Dispersion Stability

[73] The dispersion stability of the scoria dispersion solution of each example was determined in a manner such that the dispersion solution was stored at 25⁰C for 1 month and the degree of precipitation thereof was observed. As a result, as shown in Table 2 below, the scoria dispersion solutions of Examples 1, 2 and 5 showed excellent dispersion stability.

[74] Table 2 [Table 2] [Table ]

[75]

Claims

[1] A photoactive composition, comprising 0.1-40 wt% of a photocatalyst in a powder or solution phase or a photocatalyst made of metal alkoxide; and 0.1-30 wt% of scoria powder, with a balance being a solvent.

[2] The photoactive composition according to claim 1, wherein the metal alkoxide is one or more selected from among any one titanium alkoxide selected from the group consisting of titanium(IV) propoxide, titanium(IV) isopropoxide, titanium(IV) diisopropoxide, titanium(IV) butoxide, titanium(IV) ethoxide and titanium(IV) methoxide; and any one zirconium alkoxide selected from the group consisting of zirconium(IV) tert-butoxide, zirconium(IV) butoxide, zirconium(IV) ethoxide, zirconium(IV) propoxide and zirconium(IV) isopropoxide.

[3] The photoactive composition according to claim 1, wherein the solvent is one or more selected from the group consisting of water; any one alcohol selected from the group consisting of methanol, ethanol, propanol, butanol and isopropanol; any one acetone selected from among diacetone alcohol and acetyl acetone; and cellosolve selected from the group consisting of methyl cellosolve, ethyl cellosolve, butyl cellosolve and cellosolve acetate.

[4] The photoactive composition according to any one of claims 1 to 3, further comprising an inorganic binder.

[5] A method of preparing a photoactive composition, comprising: dissolving metal alkoxide in a solvent, thus preparing a photocatalyst solution; mixing the photocatalyst solution with scoria powder and then performing milling, thus preparing a scoria dispersion solution; adding a solvent to the scoria dispersion solution, thus controlling a solid content of the solution; and adding an acid or a base to the solution having the controlled solid content, thus adjusting a pH of the solution.

[6] The method according to claim 5, wherein the milling is performed at 100-500 rpm for 4-24 hours using stabilized zirconia balls having a diameter of 1-10 mm.