JP3758245B2 - Photocatalyst functional material - Google Patents
Photocatalyst functional material Download PDFInfo
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- JP3758245B2 JP3758245B2 JP21585596A JP21585596A JP3758245B2 JP 3758245 B2 JP3758245 B2 JP 3758245B2 JP 21585596 A JP21585596 A JP 21585596A JP 21585596 A JP21585596 A JP 21585596A JP 3758245 B2 JP3758245 B2 JP 3758245B2
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- Prior art keywords
- photocatalytic
- titanium oxide
- functional material
- surface layer
- particles
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- 239000000463 material Substances 0.000 title claims description 34
- 239000011941 photocatalyst Substances 0.000 title description 21
- 230000001699 photocatalysis Effects 0.000 claims description 48
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 42
- 239000002245 particle Substances 0.000 claims description 41
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 40
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 claims description 22
- 239000002344 surface layer Substances 0.000 claims description 18
- 238000005245 sintering Methods 0.000 claims description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- 150000001875 compounds Chemical class 0.000 claims description 8
- 230000001443 photoexcitation Effects 0.000 claims description 7
- 230000009471 action Effects 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 6
- 239000000428 dust Substances 0.000 claims description 3
- 230000002209 hydrophobic effect Effects 0.000 claims description 3
- 238000005406 washing Methods 0.000 claims description 3
- 230000005284 excitation Effects 0.000 claims description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 10
- LSDPWZHWYPCBBB-UHFFFAOYSA-N Methanethiol Chemical compound SC LSDPWZHWYPCBBB-UHFFFAOYSA-N 0.000 description 8
- 238000004332 deodorization Methods 0.000 description 8
- 239000007789 gas Substances 0.000 description 8
- 238000000354 decomposition reaction Methods 0.000 description 7
- 239000000758 substrate Substances 0.000 description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- 230000000844 anti-bacterial effect Effects 0.000 description 6
- 229910000019 calcium carbonate Inorganic materials 0.000 description 5
- 239000010408 film Substances 0.000 description 5
- BDAGIHXWWSANSR-NJFSPNSNSA-N hydroxyformaldehyde Chemical compound O[14CH]=O BDAGIHXWWSANSR-NJFSPNSNSA-N 0.000 description 5
- 229910000018 strontium carbonate Inorganic materials 0.000 description 5
- 230000003373 anti-fouling effect Effects 0.000 description 4
- AYJRCSIUFZENHW-UHFFFAOYSA-L barium carbonate Chemical compound [Ba+2].[O-]C([O-])=O AYJRCSIUFZENHW-UHFFFAOYSA-L 0.000 description 4
- 239000011521 glass Substances 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 3
- 239000000920 calcium hydroxide Substances 0.000 description 3
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 239000010459 dolomite Substances 0.000 description 3
- 229910000514 dolomite Inorganic materials 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000011259 mixed solution Substances 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- 235000019738 Limestone Nutrition 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- AYJRCSIUFZENHW-DEQYMQKBSA-L barium(2+);oxomethanediolate Chemical compound [Ba+2].[O-][14C]([O-])=O AYJRCSIUFZENHW-DEQYMQKBSA-L 0.000 description 2
- 239000004566 building material Substances 0.000 description 2
- 239000006229 carbon black Substances 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000001877 deodorizing effect Effects 0.000 description 2
- 239000006028 limestone Substances 0.000 description 2
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 2
- 239000001095 magnesium carbonate Substances 0.000 description 2
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 2
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 2
- 239000000347 magnesium hydroxide Substances 0.000 description 2
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 238000006864 oxidative decomposition reaction Methods 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 2
- 229910001887 tin oxide Inorganic materials 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 239000012780 transparent material Substances 0.000 description 2
- 239000005995 Aluminium silicate Substances 0.000 description 1
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 235000012211 aluminium silicate Nutrition 0.000 description 1
- 238000000149 argon plasma sintering Methods 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000011449 brick Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 229910001634 calcium fluoride Inorganic materials 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000004567 concrete Substances 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- GUJOJGAPFQRJSV-UHFFFAOYSA-N dialuminum;dioxosilane;oxygen(2-);hydrate Chemical compound O.[O-2].[O-2].[O-2].[Al+3].[Al+3].O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O GUJOJGAPFQRJSV-UHFFFAOYSA-N 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 230000002070 germicidal effect Effects 0.000 description 1
- 230000004313 glare Effects 0.000 description 1
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- ORUIBWPALBXDOA-UHFFFAOYSA-L magnesium fluoride Chemical compound [F-].[F-].[Mg+2] ORUIBWPALBXDOA-UHFFFAOYSA-L 0.000 description 1
- 229910001635 magnesium fluoride Inorganic materials 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 1
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910001507 metal halide Inorganic materials 0.000 description 1
- 150000005309 metal halides Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 229910052901 montmorillonite Inorganic materials 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 description 1
- SIWVEOZUMHYXCS-UHFFFAOYSA-N oxo(oxoyttriooxy)yttrium Chemical compound O=[Y]O[Y]=O SIWVEOZUMHYXCS-UHFFFAOYSA-N 0.000 description 1
- 238000000634 powder X-ray diffraction Methods 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
Landscapes
- Apparatus For Disinfection Or Sterilisation (AREA)
- Disinfection, Sterilisation Or Deodorisation Of Air (AREA)
- Catalysts (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、耐摩耗性に優れた、防臭、抗菌、防汚等の効果を有する光触媒機能材に関する。
【０００２】
【従来の技術】
近年、防臭、抗菌、油分解、防汚、水処理、気体分解、有機合成等の分野において、光触媒を利用することが提案されている。
その態様としては、当初は懸濁液としての利用が提案されていたが、長期使用性等の観点から、最近では基材上に薄膜状に固定して利用する提案が増加している。
光触媒を基材上に薄膜状に固定して利用する場合、光触媒粒子が外気に接するように露出固定すると、結着剤と混合して固定する場合と比較して、防臭、抗菌、油分解等において、より低い照度の光触媒が励起される光の照射で、反応が促進されるようになる。
その理由は、光触媒性酸化チタン粒子の少なくとも一部が外気に露出されているようにすることにより、光触媒の光励起により生成する正孔と電子、及びそれらと酸素種の反応により生成した活性酸素種が、基材表面への拡散を伴わず直接部材表面に付着する微生物や有機物、吸着する気体に作用するようになるためである。
基材上に光触媒粒子が外気に接するように露出固定するように固定する方法としては、光触媒ゾルを基材に塗布し、焼成する方法が簡便である。しかし、この方法で基材上に耐摩耗性に優れた光触媒粒子膜を固定しようとすると、光触媒粒子膜上の光触媒粒子同士の結合を強める必要性が生じる。そのために、従来の方法においては、光触媒粒子同士が焼結する８００℃以上の高温で焼成していた。
【０００３】
【発明の解決すべき課題】
しかしながら、光触媒粒子同士が焼結する程度の高温で焼成する場合、当然に光触媒粒子は粒成長を生じるので、薄膜上の光触媒粒子の比表面積は低下してしまう。そのため、光触媒活性が３００〜７００℃程度の粒成長を生じない程度の低温で焼成した場合と比較して、光触媒活性が低下するという問題があった。
そこで、本発明では、光触媒活性に優れる基材表面に、光触媒性酸化チタン粒子が、少なくとも一部が外気に露出されるように固定された表面層が形成された構造の光触媒機能材において、表面層の耐摩耗性に優れ、かつ上記比表面積低下による光触媒活性の低下のない光触媒機能材を提供することを目的とする。
【０００４】
【課題を解決するための手段、及び作用】
本発明では上記課題を解決すべく、基材表面に、アナターゼ型光触媒性酸化チタン粒子が、少なくとも一部が外気に露出されるように固定された表面層が形成された光触媒機能材において、前記表面層は、光触媒性酸化チタン粒子より低温で焼結しうる第二成分粒子を含有し、前記第二成分粒子の焼結作用により固定されていることを特徴とする光触媒機能材を提供する。
チタンより低温で焼結しうる第二成分物質の焼結作用で表面層を固定することにより、酸化チタン粒子が粒成長して活性を低下させることなく、強固に基材に固定できる。また粒子状の第二成分物質を焼結させることにより、光触媒性酸化チタン粒子と酸化チタンより第二成分物質を混合して担持させても、光触媒性酸化チタン粒子が完全に前記物質で覆われることを防止できるので、光触媒性酸化チタン粒子の少なくとも一部が外気に露出された光触媒機能材を容易に製造できる。
【０００５】
本発明の好ましい態様においては、表面層は０．４μｍ以下の厚みで固定されているようにする。
このようにすることで、建材、透明材（ガラス、鏡等）などの高度の意匠性が要求される基材に、光触媒性酸化チタンを適用する場合においても、光の干渉、散乱によって意匠性が損なわれないようにできる。
【０００６】
本発明の好ましい態様においては、表面層の屈折率は２以下であるようにする。このようにすることで、建材、透明材（ガラス、鏡等）などの高度の意匠性が要求される基材に、光触媒性酸化チタンを適用する場合においても、反射防止性を付与することができるので、ギラギラ感をなくすことができる。
【０００７】
本発明の好ましい態様においては、低温で焼結しうる物質はＩＩａ族化合物であり、かつＩＩａ族化合物の焼結助剤としてフッ化リチウムが添加されているようにする。
ＩＩａ族化合物は、フッ化リチウムを焼結助剤とすれば、６００〜７００℃程度で焼結されるので、光触媒性酸化チタンの粒成長を伴うことなく、表面層を強固に固定できる。
【０００８】
本発明の好ましい態様においては、光触媒性酸化チタン粒子の平均結晶子径は２０ｎｍ以下であるようにする。
酸化チタン粒子の平均結晶子径が小さい程、光触媒活性を高めることができ、より優れた抗菌、有機物分解性、気体分解性を確保できる。
【０００９】
本発明の好ましい態様においては、気体分解機能材表面は、光触媒性酸化チタンの光励起に応じて、水との接触角に換算して３０゜以下の親水性を呈するようにする。
このようにすることで、光触媒による酸化分解では対処できないカーボンブラック等の都市煤塵に含有される疎水性の汚れが降雨又は水洗のみで洗い流せるようになる。
【００１０】
本発明の好ましい態様においては、気体分解機能材表面は、光触媒性酸化チタンの光励起に応じて、水との接触角に換算して１０゜以下の親水性を呈するようにする。
このようにすることで、光触媒による酸化分解では対処できないカーボンブラック等の都市煤塵に含有される疎水性の汚れの他、泥汚れ等の無機質の汚れも降雨又は水洗のみで洗い流せるようになる。
【００１１】
【発明の実施の形態】
以下に本発明の具体的構成について説明する。
光触媒性アナターゼ型酸化チタンの光励起は、光触媒性アナターゼ型酸化チタンの伝導帯と価電子帯との間のバンドギャップよりも大きなエネルギー（すなわち３８７ｎｍ以下の波長）を有する光を照射することにより行う。
その光源としては、蛍光灯、殺菌灯、白熱電灯、メタルハライドランプ、水銀ランプ、室内照明、太陽光、及びそれらの光源から照射される光を低損失のファイバーで誘導した光源等を利用できる。
光触媒性アナターゼ型酸化チタンの光励起により、防臭、抗菌、気体分解、防汚等を行うには、上記励起光の照度は、０．００１ｍＷ／ｃｍ２以上、好ましくは０．０１ｍＷ／ｃｍ２以上、より好ましくは０．１ｍＷ／ｃｍ２以上であれば充分である。
【００１２】
本発明に使用できる基材は、第二成分粒子が焼結しうる温度で耐え得る基材であり、金属、セラミック、ガラス、コンクリート、石、セメント、陶磁器、レンガ等が好適に利用できる。
光触媒機能材とは、上記基材に、光触媒が固定され、光励起により防臭、抗菌、気体分解、防汚等の機能を発揮しうる材料をいう。
【００１３】
光触媒性酸化チタン粒子より低温で焼結しうる第二成分粒子には、例えば酸化錫、フッ化リチウムを焼結助剤とする炭酸マグネシウム、水酸化マグネシウム、炭酸カルシウム、炭酸ストロンチウム、炭酸バリウム、ドロマイト、石灰石、水酸化カルシウムなどが好適に利用できる。
第二成分粒子の焼結作用については、酸化チタンの固溶を伴わなければ、その機構は基本的には問わない。ネック形成を伴う固相焼結、蒸発−凝縮機構等による液相焼結等が好適に利用できる。
【００１４】
ＩＩａ族化合物とは、マグネシウム、カルシウム、ストロンチウム、バリウムを含む化合物であり、例えば、炭酸マグネシウム、水酸化マグネシウム、炭酸カルシウム、炭酸ストロンチウム、炭酸バリウム、ドロマイト、石灰石、水酸化カルシウム等が好適に利用できる。
【００１５】
表面層の膜厚が、０．４μｍ以下、より好ましくは０．２μｍ以下だと、光の散乱、干渉による発色を防止できるとともに、ガラス等の透明基材においては、基材の透明性を確保できる。更に、膜厚を薄くすれば表面層の耐摩耗性が向上する。
【００１６】
また、表面層による反射を防止するため、表面層の屈折率を２以下にするとよい。それには、アナターゼ型酸化チタンの屈折率は２．５なので、第二成分粒子に屈折率が２よりも小さい物質を選ぶか、第三成分として屈折率が２よりも小さい物質を添加する。屈折率が２よりも小さい物質としては、炭酸カルシウム（屈折率１．６）、水酸化カルシウム（同１．６）、炭酸マグネシウム（同１．５）、炭酸ストロンチウム（同１．５）、ドロマイト（同１．７）、フッ化カルシウム（同１．４）、フッ化マグネシウム（同１．４）、シリカ（同１．５）、アルミナ（同１．６）、ケイ砂（同１．６）、ゼオライト（同１．５）、モンモリロナイト（同１．５）、カオリン（同１．６）、セリサイト（同１．６）、酸化第二鉄（同１．８）、酸化錫（同１．９）、酸化イットリウム（同１．９）等が好適に利用できる。
【００１７】
光触媒性アナターゼ型酸化チタン粒子の平均結晶子径とは、粉末Ｘ線回折法により得られた回折パターンにおけるアナターゼ型酸化チタンの最強ピーク（２θ＝２５．２゜）における半価幅からシェラー式により算出される結晶子径をいう。水との接触角とは、表面にマイクロシリンジにより水滴を滴下し、滴下後３０秒後の水濡れ角を接触角測定器により測定した値をいう。
【００１８】
【実施例】
実施例１
５０×１００ｍｍの無釉タイル（東陶機器製、ＡＳ０２Ｍ１１）基材に、アナターゼ型酸化チタンゾル（石原産業製、ＳＴＳ−１１）と炭酸カルシウムとフッ化リチウムの混合液を塗布し、６５０℃で１時間焼成した。ここで、アナターゼ型酸化チタン１００重量部に対し、炭酸カルシウム２０重量部、フッ化リチウム５重量部とした。
実施例２
５０×１００ｍｍの無釉タイル（東陶機器製、ＡＳ０２Ｍ１１）基材に、アナターゼ型酸化チタンゾル（石原産業製、ＳＴＳ−１１）と炭酸ストロンチウムとフッ化リチウムの混合液を塗布し、６５０℃で１時間焼成した。ここで、アナターゼ型酸化チタン１００重量部に対し、炭酸ストロンチウム２０重量部、フッ化リチウム１０重量部とした。
実施例３
５０×１００ｍｍの無釉タイル（東陶機器製、ＡＳ０２Ｍ１１）基材に、アナターゼ型酸化チタンゾル（石原産業製、ＳＴＳ−１１）と炭酸バリウムとフッ化リチウムの混合液を塗布し、６５０℃で１時間焼成した。ここで、アナターゼ型酸化チタン１００重量部に対し、炭酸バリウム２０重量部、フッ化リチウム１０重量部とした。
比較例１
５０×１００ｍｍの無釉タイル（東陶機器製、ＡＳ０２Ｍ１１）基材に、アナターゼ型酸化チタンゾルを塗布し、６５０℃で１時間焼成した。
比較例２
５０×１００ｍｍの無釉タイル（東陶機器製、ＡＳ０２Ｍ１１）基材に、アナターゼ型酸化チタンゾルを塗布し、８８０℃で１時間焼成した。
【００１９】
上記試料について、防臭性及び耐摩耗性を測定した。
防臭性は以下の要領で測定した。石英ガラス製の容積１１リッターのデシケータ内に夫々の試料を配置し、メチルメルカプタンを含有する窒素ガスをメチルメルカプタンの濃度が３ｐｐｍになるように注入した。試料から８ｃｍの距離のところに、４ＷのＢＬＢ蛍光灯を配置し、０．３ｍＷ／ｃｍ２の紫外線照度で紫外線を照射した。３０分後にデシケータ内のガスを採取し、ガスクロマトグラフによりメチルメルカプタン濃度を測定し、メチルメルカプタンの除去率を求めた。耐摩耗性は、試料表面にプラスチック消しゴムを往復２０回摺動させ、その後の試料表面の外観を観察し、変化が認められなければ○、キズが観察されれば△、膜が剥離すれば×と評価した。
結果を表１に示す。
【００２０】
【表１】
表１より、表面層に、光触媒性アナターゼ型酸化チタン粒子のみを塗布焼成した場合には、低温で焼成すると良好な防臭性を示すが耐摩耗性が充分でなく（比較例１）、高温で焼成すると良好な耐摩耗性を示すが防臭性が充分でない。それに対し、光触媒性アナターゼ型酸化チタン粒子以外に、ＩＩａ族化合物とその焼結助剤であるフッ化リチウムを含有する実施例１〜３では、良好な防臭性及び耐摩耗性を有するようになることがわかる。
【００２２】
【発明の効果】
光触媒活性に優れる基材表面に、光触媒性酸化チタン粒子が、少なくとも一部が外気に露出されるように固定された表面層が形成された構造の光触媒機能材において、表面層は、光触媒性酸化チタン粒子より低温で焼結しうる第二成分粒子を含有し、前記第二成分粒子の焼結作用により固定されているようにすることにより、表面層の耐摩耗性に優れ、かつ比表面積低下による光触媒活性の低下のない光触媒機能材となる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photocatalytic functional material excellent in wear resistance and having effects such as deodorization, antibacterial and antifouling.
[0002]
[Prior art]
In recent years, it has been proposed to use a photocatalyst in the fields of deodorization, antibacterial, oil decomposition, antifouling, water treatment, gas decomposition, organic synthesis and the like.
As its mode, the use as a suspension was originally proposed, but from the viewpoint of long-term usability and the like, recently, proposals for use in a thin film form on a substrate are increasing.
When using the photocatalyst fixed in a thin film on the substrate, the photocatalyst particles are exposed and fixed so as to be in contact with the outside air, compared with the case where the photocatalyst particles are mixed with the binder and fixed, deodorizing, antibacterial, oil decomposition, etc. The reaction is promoted by irradiation with light that excites a photocatalyst having a lower illuminance.
The reason is that by making at least a part of the photocatalytic titanium oxide particles exposed to the outside air, the active oxygen species generated by the reaction of the holes and electrons generated by photoexcitation of the photocatalyst and the oxygen species thereof. This is because it acts on microorganisms and organic substances adhering directly to the surface of the member without diffusion to the surface of the base material, and adsorbed gas.
As a method of fixing the photocatalyst particles so that the photocatalyst particles are exposed and fixed on the base material, a method of applying the photocatalyst sol to the base material and baking it is simple. However, if it is attempted to fix the photocatalyst particle film having excellent wear resistance on the substrate by this method, it becomes necessary to strengthen the bond between the photocatalyst particles on the photocatalyst particle film. Therefore, in the conventional method, it baked at the high temperature of 800 degreeC or more at which photocatalyst particles sinter.
[0003]
Problems to be Solved by the Invention
However, when firing at such a high temperature that the photocatalyst particles sinter, the photocatalyst particles naturally grow, so that the specific surface area of the photocatalyst particles on the thin film decreases. For this reason, there is a problem that the photocatalytic activity is reduced as compared with the case where the photocatalytic activity is fired at a low temperature that does not cause grain growth of about 300 to 700 ° C.
Therefore, in the present invention, in the photocatalytic functional material having a structure in which a surface layer in which at least a part of the photocatalytic titanium oxide particles is fixed to the outside air is formed on the surface of the base material excellent in photocatalytic activity, An object of the present invention is to provide a photocatalytic functional material which is excellent in wear resistance of a layer and does not have a reduction in photocatalytic activity due to the reduction in the specific surface area.
[0004]
[Means for solving the problems and actions]
In the present invention, in order to solve the above-mentioned problems, in the photocatalytic functional material, the surface of the base material is formed with a surface layer in which anatase-type photocatalytic titanium oxide particles are fixed so that at least a part thereof is exposed to the outside air. The surface layer contains the second component particles that can be sintered at a lower temperature than the photocatalytic titanium oxide particles, and is fixed by the sintering action of the second component particles.
By fixing the surface layer by the sintering action of the second component material that can be sintered at a temperature lower than that of titanium, the titanium oxide particles can be firmly fixed to the substrate without growing and reducing the activity. Further, by sintering the particulate second component material, the photocatalytic titanium oxide particles are completely covered with the material even if the second component material is mixed and supported from the photocatalytic titanium oxide particles and titanium oxide. Therefore, it is possible to easily produce a photocatalytic functional material in which at least a part of the photocatalytic titanium oxide particles are exposed to the outside air.
[0005]
In a preferred embodiment of the present invention, the surface layer is fixed with a thickness of 0.4 μm or less.
In this way, even when photocatalytic titanium oxide is applied to a base material that requires a high degree of design, such as building materials and transparent materials (glass, mirrors, etc.), the design properties can be reduced by light interference and scattering. Can be kept intact.
[0006]
In a preferred embodiment of the present invention, the refractive index of the surface layer is 2 or less. In this way, even when photocatalytic titanium oxide is applied to a base material that requires a high degree of design, such as building materials and transparent materials (glass, mirrors, etc.), antireflection properties can be imparted. Because it can, it can eliminate the glare.
[0007]
In a preferred embodiment of the present invention, the substance that can be sintered at a low temperature is a Group IIa compound, and lithium fluoride is added as a sintering aid for the Group IIa compound.
Since the group IIa compound is sintered at about 600 to 700 ° C. when lithium fluoride is used as a sintering aid, the surface layer can be firmly fixed without accompanying grain growth of photocatalytic titanium oxide.
[0008]
In a preferred embodiment of the present invention, the photocatalytic titanium oxide particles have an average crystallite size of 20 nm or less.
The smaller the average crystallite size of the titanium oxide particles, the higher the photocatalytic activity, and the better antibacterial, organic matter decomposability, and gas decomposability can be ensured.
[0009]
In a preferred embodiment of the present invention, the surface of the gas decomposition functional material exhibits a hydrophilicity of 30 ° or less in terms of a contact angle with water according to photoexcitation of photocatalytic titanium oxide.
By doing so, hydrophobic dirt contained in urban dust such as carbon black, which cannot be dealt with by oxidative decomposition using a photocatalyst, can be washed away only by rainfall or water washing.
[0010]
In a preferred embodiment of the present invention, the surface of the gas decomposition functional material exhibits a hydrophilicity of 10 ° or less in terms of a contact angle with water according to photoexcitation of photocatalytic titanium oxide.
By doing so, in addition to hydrophobic dirt contained in urban dust such as carbon black that cannot be dealt with by oxidative decomposition by a photocatalyst, inorganic dirt such as mud dirt can be washed away only by rain or water washing.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The specific configuration of the present invention will be described below.
Photoexcitation of the photocatalytic anatase-type titanium oxide is performed by irradiating light having energy larger than the band gap between the conduction band and the valence band of the photocatalytic anatase-type titanium oxide (that is, a wavelength of 387 nm or less).
As the light source, a fluorescent lamp, a germicidal lamp, an incandescent lamp, a metal halide lamp, a mercury lamp, indoor lighting, sunlight, a light source in which light emitted from these light sources is guided by a low-loss fiber, or the like can be used.
In order to perform deodorization, antibacterial, gas decomposition, antifouling, etc. by photoexcitation of photocatalytic anatase titanium oxide, the illuminance of the excitation light is 0.001 mW / cm 2 or more, preferably 0.01 mW / cm 2 or more, More preferably, 0.1 mW / cm 2 or more is sufficient.
[0012]
The base material that can be used in the present invention is a base material that can withstand the temperature at which the second component particles can be sintered, and metals, ceramics, glass, concrete, stones, cement, ceramics, bricks, and the like can be suitably used.
The photocatalytic functional material is a material in which a photocatalyst is fixed to the base material and can exhibit functions such as deodorization, antibacterial, gas decomposition, and antifouling by photoexcitation.
[0013]
The second component particles that can be sintered at a lower temperature than the photocatalytic titanium oxide particles include, for example, magnesium oxide, magnesium hydroxide, calcium carbonate, strontium carbonate, barium carbonate, dolomite with tin oxide and lithium fluoride as a sintering aid. Limestone, calcium hydroxide, and the like can be suitably used.
Regarding the sintering action of the second component particles, the mechanism is basically not limited as long as it does not involve solid solution of titanium oxide. Solid phase sintering with neck formation, liquid phase sintering by an evaporation-condensation mechanism, etc. can be suitably used.
[0014]
The IIa group compound is a compound containing magnesium, calcium, strontium, and barium. For example, magnesium carbonate, magnesium hydroxide, calcium carbonate, strontium carbonate, barium carbonate, dolomite, limestone, calcium hydroxide, and the like can be suitably used. .
[0015]
When the film thickness of the surface layer is 0.4 μm or less, more preferably 0.2 μm or less, it is possible to prevent color development due to light scattering and interference, and in the case of a transparent substrate such as glass, the transparency of the substrate is ensured. it can. Furthermore, if the film thickness is reduced, the wear resistance of the surface layer is improved.
[0016]
In order to prevent reflection by the surface layer, the refractive index of the surface layer is preferably 2 or less. For this purpose, since the refractive index of anatase-type titanium oxide is 2.5, a substance having a refractive index lower than 2 is selected as the second component particle, or a substance having a refractive index lower than 2 is added as the third component. Substances having a refractive index smaller than 2 include calcium carbonate (refractive index 1.6), calcium hydroxide (1.6), magnesium carbonate (1.5), strontium carbonate (1.5), and dolomite. (Same as 1.7), calcium fluoride (same as 1.4), magnesium fluoride (same as 1.4), silica (same as 1.5), alumina (same as 1.6), silica sand (same as 1.6) ), Zeolite (1.5), montmorillonite (1.5), kaolin (1.6), sericite (1.6), ferric oxide (1.8), tin oxide (1.5) 1.9) and yttrium oxide (1.9) can be suitably used.
[0017]
The average crystallite size of the photocatalytic anatase-type titanium oxide particles is determined by the Scherrer equation from the half-value width at the strongest peak (2θ = 25.2 °) of the anatase-type titanium oxide in the diffraction pattern obtained by the powder X-ray diffraction method. This is the calculated crystallite size. The contact angle with water refers to a value obtained by dropping a water droplet on the surface with a microsyringe and measuring a water wetting angle 30 seconds after the dropping with a contact angle measuring device.
[0018]
【Example】
Example 1
A mixed solution of anatase-type titanium oxide sol (manufactured by Ishihara Sangyo Co., Ltd., STS-11), calcium carbonate and lithium fluoride is applied to a 50 × 100 mm solid tile (manufactured by Tosoh Kikai, AS02M11), and 1 at 650 ° C. Baked for hours. Here, 20 parts by weight of calcium carbonate and 5 parts by weight of lithium fluoride were used per 100 parts by weight of anatase-type titanium oxide.
Example 2
A mixed solution of anatase-type titanium oxide sol (manufactured by Ishihara Sangyo Co., Ltd., STS-11), strontium carbonate and lithium fluoride is applied to a 50 × 100 mm solid tile (manufactured by Tosoh Kikai, AS02M11), and 1 at 650 ° C. Baked for hours. Here, 20 parts by weight of strontium carbonate and 10 parts by weight of lithium fluoride were used with respect to 100 parts by weight of anatase-type titanium oxide.
Example 3
A mixed solution of anatase-type titanium oxide sol (manufactured by Ishihara Sangyo Co., Ltd., STS-11), barium carbonate and lithium fluoride is applied to a 50 × 100 mm plain tile (manufactured by Tosoh Kikai Co., Ltd., AS02M11), and 1 at 650 ° C. Baked for hours. Here, 20 parts by weight of barium carbonate and 10 parts by weight of lithium fluoride were used per 100 parts by weight of anatase type titanium oxide.
Comparative Example 1
Anatase-type titanium oxide sol was applied to a 50 × 100 mm plain tile (AS02M11, manufactured by Tosoh Kikai Co., Ltd.) and baked at 650 ° C. for 1 hour.
Comparative Example 2
Anatase-type titanium oxide sol was applied to a 50 × 100 mm glazed tile (manufactured by Tosoh Kikai, AS02M11) and baked at 880 ° C. for 1 hour.
[0019]
The sample was measured for deodorization and wear resistance.
The deodorization property was measured as follows. Each sample was placed in a 11 liter desiccator made of quartz glass, and nitrogen gas containing methyl mercaptan was injected so that the concentration of methyl mercaptan was 3 ppm. A 4 W BLB fluorescent lamp was placed at a distance of 8 cm from the sample and irradiated with ultraviolet rays at an ultraviolet illuminance of 0.3 mW / cm 2 . After 30 minutes, the gas in the desiccator was collected, the methyl mercaptan concentration was measured by gas chromatography, and the removal rate of methyl mercaptan was determined. Abrasion resistance is determined by sliding a plastic eraser 20 times back and forth on the sample surface, and then observing the appearance of the sample surface. If no change is observed, △, if scratch is observed, △, if the film is peeled, × It was evaluated.
The results are shown in Table 1.
[0020]
[Table 1]
From Table 1, when only the photocatalytic anatase-type titanium oxide particles are applied and fired on the surface layer, the deodorizing property is exhibited when fired at a low temperature, but the wear resistance is not sufficient (Comparative Example 1). When baked, it exhibits good wear resistance, but its deodorization is not sufficient. On the other hand, in Examples 1 to 3 containing a group IIa compound and lithium fluoride as a sintering aid in addition to the photocatalytic anatase-type titanium oxide particles, it has good deodorization and wear resistance. I understand that.
[0022]
【The invention's effect】
In a photocatalytic functional material having a structure in which a surface layer in which photocatalytic titanium oxide particles are fixed so that at least a part thereof is exposed to the outside air is formed on the surface of a substrate having excellent photocatalytic activity, the surface layer is formed by photocatalytic oxidation. Contains second component particles that can be sintered at a lower temperature than titanium particles, and is fixed by the sintering action of the second component particles, so that the surface layer has excellent wear resistance and has a reduced specific surface area. It becomes a photocatalyst functional material without a decrease in photocatalytic activity due to.
Claims (5)
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| JP3050071B2 (en) * | 1994-12-21 | 2000-06-05 | 株式会社イナックス | Method for producing sintered calcium carbonate |
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