JP4227802B2 - Photocatalyst dispersed toner - Google Patents
Photocatalyst dispersed toner Download PDFInfo
- Publication number
- JP4227802B2 JP4227802B2 JP2002350672A JP2002350672A JP4227802B2 JP 4227802 B2 JP4227802 B2 JP 4227802B2 JP 2002350672 A JP2002350672 A JP 2002350672A JP 2002350672 A JP2002350672 A JP 2002350672A JP 4227802 B2 JP4227802 B2 JP 4227802B2
- Authority
- JP
- Japan
- Prior art keywords
- anatase
- photocatalyst
- titania powder
- mass
- group
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000011941 photocatalyst Substances 0.000 title description 8
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 109
- 239000000843 powder Substances 0.000 claims description 50
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 19
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 16
- 239000002245 particle Substances 0.000 claims description 14
- -1 3,4-epoxycyclohexyl group Chemical group 0.000 claims description 12
- POAOYUHQDCAZBD-UHFFFAOYSA-N 2-butoxyethanol Chemical compound CCCCOCCO POAOYUHQDCAZBD-UHFFFAOYSA-N 0.000 claims description 7
- 125000000217 alkyl group Chemical group 0.000 claims description 7
- 239000012046 mixed solvent Substances 0.000 claims description 7
- 125000004432 carbon atom Chemical group C* 0.000 claims description 6
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 claims description 4
- 125000003118 aryl group Chemical group 0.000 claims description 3
- 239000011248 coating agent Substances 0.000 description 30
- 238000000576 coating method Methods 0.000 description 30
- 239000011230 binding agent Substances 0.000 description 19
- 230000001699 photocatalysis Effects 0.000 description 15
- 239000008199 coating composition Substances 0.000 description 13
- 238000002156 mixing Methods 0.000 description 13
- 229910010413 TiO 2 Inorganic materials 0.000 description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 7
- 230000002776 aggregation Effects 0.000 description 7
- 238000001556 precipitation Methods 0.000 description 7
- 238000004220 aggregation Methods 0.000 description 6
- 230000007062 hydrolysis Effects 0.000 description 6
- 238000006460 hydrolysis reaction Methods 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 239000003973 paint Substances 0.000 description 5
- 239000000758 substrate Substances 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- 125000003545 alkoxy group Chemical group 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 238000003860 storage Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- 239000008119 colloidal silica Substances 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 125000000524 functional group Chemical group 0.000 description 3
- 230000003301 hydrolyzing effect Effects 0.000 description 3
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 229910001220 stainless steel Inorganic materials 0.000 description 3
- 239000010935 stainless steel Substances 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 240000008415 Lactuca sativa Species 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 150000004703 alkoxides Chemical class 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000011324 bead Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000013329 compounding Methods 0.000 description 2
- 230000018044 dehydration Effects 0.000 description 2
- 238000006297 dehydration reaction Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 235000012045 salad Nutrition 0.000 description 2
- 150000004756 silanes Chemical class 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- 229910001369 Brass Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- 239000010951 brass Substances 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 239000004567 concrete Substances 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000006482 condensation reaction Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 238000009503 electrostatic coating Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- BFXIKLCIZHOAAZ-UHFFFAOYSA-N methyltrimethoxysilane Chemical compound CO[Si](C)(OC)OC BFXIKLCIZHOAAZ-UHFFFAOYSA-N 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 238000007650 screen-printing Methods 0.000 description 1
- 239000010454 slate Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
Landscapes
- Catalysts (AREA)
- Pigments, Carbon Blacks, Or Wood Stains (AREA)
Description
【０００１】
【産業上の利用分野】
本発明は、各種器物，機器の基材表面に光触媒塗膜を形成する際に使用される光触媒分散トナーに関する。
【０００２】
【従来の技術】
塗膜に光触媒粒子を分散させると、セルフクリーニング作用が塗膜表面に付与され、長期間にわたって清浄な塗膜表面が維持される。有機物ベースの塗膜は光照射で生成した活性酸素によって分解しチョーキング現象が発生するので、活性酸素による分解のない無機物をベースに光触媒塗膜を形成している。
【０００３】
光触媒粒子として代表的なアナターゼ型チタニア粉末を用いて塗料組成物を調合すると、バインダとの混合と同時にアナターゼ型チタニア粉末の凝集沈殿が開始し、貯蔵安定性が極めて悪い。そのため、光触媒分散トナー及び無機系バインダを個別に用意しておき、塗装直前に両者を混合する方法が採用されている。たとえば、テトラエトキシシラン等のアルコキシドを溶解した水／エタノール混合溶媒にＴｉＯ2の水分散ゾルを混合し（ＷＯ９６／２９３７５）、或いはオルガノシリカゾルを有機溶媒に溶解させた溶液にＴｉＯ2粉末を分散させること（特開平８−６７８３５号公報）により塗料組成物を調合している。
【０００４】
【発明が解決しようとする課題】
塗装直前に光触媒分散トナー，無機系バインダを混合することにより調合した塗料組成物でも、アナターゼ型チタニア粉末の凝集沈殿が進行するため塗装性や塗膜性状が安定化しない。凝集沈殿は、アナターゼ型チタニア粉末のゼータ電位が４.５〜６.０の範囲にあり、貯蔵安定化のために調整した無機系バインダのｐＨ３〜６.５に重複することが原因である。
【０００５】
そこで、本発明者等は、アナターゼ型チタニア粉末の凝集沈殿を防止するため、バインダ成分であるオルガノアルコキシシランの一部を光触媒分散トナーに予め添加することを提案した（特開２００２−１０５３５７号公報）。光触媒分散トナーに添加されたオルガノアルコキシシランがアナターゼ型チタニア粉末の表面を覆うと、粉末表面のゼータ電位が無機系バインダのｐＨ値から外れ、結果として無機系バインダと混合した場合でもアナターゼ型チタニア粉末の凝集沈殿が抑制されるものと推察される。
【０００６】
【課題を解決するための手段】
本発明は、先願・特開２００２−１０５３５７号公報で紹介した光触媒塗料組成物を更に改良すべく案出されたものであり、部分加水分解によりオルガノアルコキシシランのアルコキシ基をアナターゼ型チタニア粉末表面のＯＨ基と反応させ、光触媒分散トナーにおいてもアナターゼ型チタニア粉末の分散性を一層改善することを目的とする。
【０００７】
本発明の光触媒分散トナーは、その目的を達成するため、イソプロパノール，ブチルセロソルブの混合溶媒にアナターゼ型チタニア粉末，オルガノアルコキシシランが少量の水と共に配合され、水添加で部分加水分解したオルガノアルコキシシランで被覆したアナターゼ型チタニア粉末が分散していることを特徴とする。水添加量は、オルガノアルコキシシランを部分加水分解させるが、オルガノアルコキシシラン相互の脱水縮合反応を進行させない０.１〜１０質量％の範囲で選定される。
【０００８】
アナターゼ型チタニア粉末としては、粒径５〜２００ｎｍの粉末が好ましく、３０〜６０質量％の割合で配合される。オルガノアルコキシシランは、一般式Ｒ1Ｓｉ(ＯＲ2)3〔Ｒ1は炭素数１〜３のアルキル基，ビニル基，3,4-エポキシシクロヘキシル基，γ-グリシドキシプロピル基又はγ-メルカプトプロピル基、Ｒ2は炭素数１〜４のアルキル基又はアリール基〕で表され、１〜１０質量％の割合で配合される。
【０００９】
【作用及び実施の形態】
光触媒分散トナーに配合したオルガノアルコキシシランは、アナターゼ型チタニア粉末の表面にオルガノアルコキシシランのまま吸着し、或いは溶剤中に単に分散した状態で存在する。吸着したオルガノアルコキシシランはアナターゼ型チタニア粉末の分散性を向上させるが、長期間にわたる貯蔵では分散性が十分とはいえない。
【００１０】
水が存在する系では、オルガノアルコキシシランのアルコキシ基が部分加水分解する。加水分解生成物がアナターゼ型チタニア粉末表面のＯＨ基と結合するので、この結合を介しアナターゼ型チタニア粉末表面にオルガノアルコキシシランが付着する。アナターゼ型チタニア粉末は、オルガノアルコキシシランの付着によって分散性が向上し、長期にわたって凝集沈殿なく光触媒分散トナー中に懸濁する。その結果、貯蔵安定性に優れた光触媒分散トナーが得られる。良好な分散性は、無機系バインダと混合した後でも維持される。
【００１１】
アナターゼ型チタニア粉末表面に対するオルガノアルコキシシランの付着量は光触媒分散トナーの水添加量で制御でき、オルガノアルコキシシラン付着による分散性の向上は０.１質量％以上の水添加量でみられる。水添加量の増加に応じてアナターゼ型チタニア粉末表面に付着するオルガノアルコキシシランが多くなり、アナターゼ型チタニア粉末の分散性が向上する。しかし、１０質量％を超える過剰量の水を添加すると、アナターゼ型チタニア粉末表面に付着するアルコキシ基の加水分解生成物が多くなりすぎ、光触媒活性が損なわれる。過剰量の水添加は、光触媒分散トナーに添加したオルガノアルコキシシラン相互の脱水縮合を促進させ、アナターゼ型チタニア粉末表面に付着する加水分解生成物の割合が却って減少する。
【００１２】
光触媒分散トナーに配合される水以外の成分は、次のように定めることが好ましい。
光触媒としては、光触媒活性が高く化学的安定性にも優れた粒径５〜２００ｎｍのアナターゼ型チタニア粉末を用い、３０〜６０質量％の割合で配合する。粒径５ｎｍの粉末は製造自体が難しく、２００ｎｍを置ける粒径では光触媒活性が不十分となる。アナターゼ型チタニア粉末の配合割合が３０質量％未満になるとチクソ性がなく粒子の沈降が早く固めのケーキになるため、トナー使用時の再分散が困難になる。逆に６０質量％を超える配合量では、チクソ性が高くなりすぎ却ってトナーとしての流動性が損なわれる。
【００１３】
オルガノアルコキシシランは、一般式Ｒ1Ｓｉ(ＯＲ2)3〔Ｒ1はアルキル基，ビニル基，3,4-エポキシシクロヘキシル基，γ-グリシドキシプロピル基又はγ-メルカプトプロピル基，Ｒ2は炭素数１〜４のアルキル基又はアリール基〕で表され、１〜１０質量％の割合で配合される。オルガノアルコキシシランは、有機官能基の導入によってシラン相互の反応が抑制され、アナターゼ型チタニア粉末の表面に付着する割合が高くなる。この点、テトラアルコキシシランでは、加水分解が過度に進行してアナターゼ型チタニア粉末の表面に付着するだけでなく、シラン相互が反応する結果としてアナターゼ型チタニア粉末の分散に寄与しない割合が高くなる。オルガノアルコキシシランであっても、有機官能基が２個以上になるとアナターゼ型チタニア粉末の表面に付着する有機物の量が増加する。過剰の有機物が付着したアナターゼ型チタニア粉末の分散トナーから作製された光触媒塗膜を光照射環境に置くと有機物が分解し、塗膜のチョーキングが短時間に進行する。そこで、Ｓｉに直接結合する有機官能基を一つだけとし、炭素数１〜３のアルキル基，ビニル基，3,4-エポキシシクロヘキシル基，γ-グリシドキシプロピル基又はγ-メルカプトプロピル基にすることが好適である。
【００１４】
オルガノアルコキシシランの配合量は、１〜１０質量％の範囲に定められる。１質量％未満の配合量では分散性の向上がみられず、逆に１０質量％を超える配合量ではアナターゼ型チタニア粉末表面の被覆率が高くなりすぎて塗膜形成後の光触媒活性が極端に低下する。オルガノアルコキシシランの配合量はアナターゼ型チタニア粉末の粒径に依存する。たとえば、７ｎｍのＴｉＯ2粉末は約３００ｍ2／ｇの大きな表面積をもつので、８質量％のオルガノアルコキシシランで最も大きな効果が得られる。粒径２０ｎｍのＴｉＯ2粉末では表面積が５０ｍ2／ｇ程度であり、オルガノアルコキシシランの配合量３質量％で最も効果的になる。
【００１５】
溶媒には、イソプロパノール，ブチルセロソルブの混合溶媒が使用される。混合比率は、イソプロパノール：４０〜６０質量％，ブチルセロソルブ：４０〜６０質量％が好ましい。混合比率の調整によって，アナターゼ型チタニア粉末の分散性が改善されると共に、光触媒分散トナーをバインダと混合した後で塗膜を形成する際に揮発スピードが適度にコントロールされるので、剥離に至るクラックの発生が防止される。
光触媒分散トナーは、オルガノアルコキシシラン，水を添加したイソプロパノール／ブチルセロソルブの混合溶媒にアナターゼ型チタニア粉末を加え、攪拌機で攪拌した後、充填したビーズが攪拌状態に維持されている横型ミルに流量１リットル／分の速さで注入することにより調製される。必要に応じ、顔料，染料等の着色剤や増粘剤等の添加材を添加することも可能である。
【００１６】
光触媒分散トナーと配合可能な無機系バインダには、アルコキシシラン及び／又はオルガノアルコキシシランを加水分解させて縮合したもの，当該加水分解縮合物に水系又はアルコール系のコロイダルシリカを配合したシリカ系、アルミニウムアルコキシドを加水分解させて縮合したもの，当該加水分解縮合物に水系又はアルコール系のコロイダルアルミナを配合したアルミナ系等が挙げられる。シリカ系，アルミナ系を混合して使用することもでき、水系，溶剤系の何れにも配合できる。塗膜に柔軟性を付与する場合には、アクリルシリケート等を配合したバインダを用いても良い。
【００１７】
光触媒分散トナー，無機系バインダから塗料を調製する際，固形分としてＴｉＯ2が５〜８０質量％となる配合比率で光触媒分散トナー，無機系バインダを混合する。十分な光触媒活性を得る上で５質量％以上のＴｉＯ2含有量が必要であるが、８０質量％を超える過剰量のＴｉＯ2が含まれると塗膜の密着性が低下する。混合に際しては、十分に攪拌された光触媒分散トナーに無機系バインダを徐々に加え、更に攪拌することにより塗料化できる。
【００１８】
調製された塗料は、スプレー法，浸漬法，フローコーティング法，ロールコート法，スクリーン印刷法，静電塗装法等によって、前処理された基材に塗布される。塗布後、８０〜１３０℃で１〜３０分加熱することにより、基材に対する密着性に優れた塗膜が形成される。塗膜の厚さは、基材の種類や用途に応じて異なるため一概に定めることはできないが、通常１〜３０μｍの範囲で調整される。光触媒塗料組成物が塗布される基材には、普通鋼，めっき鋼板，ステンレス鋼板，アルミニウム，銅、真鍮等の金属や、セメント，コンクリート，タイル，スレート板，ガラス，石材等がある。加熱時の温度によっては、プラスチック等の有機材料にも塗装可能である。
【００１９】
【実施例】
アナターゼ型チタニア粉末分散トナーの調製
イソプロパノール：５０質量％，ブチルセロソルブ：５０質量％の混合溶媒に３質量％のオルガノアルコキシシラン，水を添加し、更に粒径２０ｎｍのアナターゼ型チタニア粉末を添加した。アナターゼ型チタニア粉末の添加量は、塗料全体の４０質量％となる割合に設定した。ビーズミルを用いた攪拌機で混合物を分散させることにより光触媒分散トナーを調製した。
【００２０】
無機系バインダの調製
水系コロイダルシリカ：２１.２ｇ（平均粒径５〜２０ｎｍ，固形分２０質量％，ｐＨ３.０）とイソプロパノール系コロイダルシリカ６２.６ｇ（平均粒径５〜２０ｎｍ，固形分２０質量％）を混合した後、メチルトリメトキシシラン１３.９ｇを加え、３０℃で５時間攪拌して加水分解を完了させた。次いで、加水分解物にイソプロパノール：３３質量％，ブチルセロソルブ：６７質量％の混合溶媒を添加し、更にアンモニア水を添加してｐＨを４.５に調整した。
得られた光触媒分散トナー，無機系バインダを固形分中のＴｉＯ2含有量が４０質量％となる割合で混合攪拌し、５０μｍのメッシュを用いて濾過し塗料化した。
【００２１】
前処理したSUS304ステンレス鋼基材に塗料をスプレー塗布し、２００℃で２０分加熱することにより膜厚１０μｍの塗膜を形成した。比較のため、水無添加の光触媒分散トナーを無機系バインダと混合することにより調製された塗料を用いて同様にSUS304ステンレス鋼基材を塗装した。
【００２２】
調製された光触媒塗料組成物の分散性及び塗膜の光触媒活性を以下の方法で評価した。
(１)光触媒塗料組成物の分散性
光触媒分散トナー，無機系バインダを混合した塗料化した後、１日経過後にＴｉＯ2粒子の凝集状態を調査した。５μｍ以上のツブが検出されない塗料組成物を○，１０μｍ以上のツブはないが５〜１０μｍのツブが検出された塗料組成物を△，１０μｍ以上のツブが生じた塗料組成物を×として分散性を評価した。
(２)塗膜の光触媒活性
付着量０.２ｍｇ／ｃｍ2でサラダ油を試験片表面に付着させ、５ｍＷ／ｃｍ2のブラックライトで２４時間照射した後、試験片に残存しているサラダ油の重量を測定し、重量減少率を油分解率として光触媒活性を評価した。
【００２３】
表１の調査結果にみられるように、オルガノアルコキシシランを添加した水無添加の光触媒分散トナーから得られた塗料組成物を使用した場合では、分散性はある程度良好であるが、光触媒活性に劣っていた。これに対し、本発明に従った光触媒分散トナーから得られた塗料組成物は、水添加の効果によって分散性が一層よくなりアナターゼ型チタニア粉末が塗膜中に均一分散しており、光触媒活性も一段と向上していた。
【００２４】
【発明の効果】
以上に説明したように、アナターゼ型チタニア粉末，オルガノアルコキシシランを配合した光触媒分散トナーに少量の水を添加してオルガノアルコキシシランを部分加水分解し、アナターゼ型チタニア粉末表面のＯＨ基にアルコキシ基の加水分解生成物を反応させるとき、アナターゼ型チタニア粉末の凝集沈殿が抑制され分散性が向上する。この光触媒分散トナーを無機系バインダと配合することにより調製された塗料組成物は、アナターゼ型チタニア粉末の優れた分散状態を維持したままで塗装原板に塗布され、アナターゼ型チタニア粉末の光触媒活性が効率よく発現する光触媒塗膜となる。[0001]
[Industrial application fields]
The present invention relates to a photocatalyst-dispersed toner used when a photocatalyst coating film is formed on the surface of a substrate of various types of equipment and devices.
[0002]
[Prior art]
When the photocatalyst particles are dispersed in the coating film, a self-cleaning action is imparted to the coating film surface, and a clean coating film surface is maintained over a long period of time. Since the organic-based coating film is decomposed by active oxygen generated by light irradiation and a choking phenomenon occurs, the photocatalytic coating film is formed on the basis of an inorganic substance that is not decomposed by active oxygen.
[0003]
When a coating composition is prepared using typical anatase type titania powder as photocatalyst particles, aggregation and precipitation of the anatase type titania powder starts simultaneously with mixing with the binder, and the storage stability is extremely poor. Therefore, a method is adopted in which a photocatalyst-dispersed toner and an inorganic binder are prepared separately and both are mixed immediately before coating. For example, an aqueous dispersion sol of TiO 2 is mixed in a water / ethanol mixed solvent in which an alkoxide such as tetraethoxysilane is dissolved (WO 96/29375), or TiO 2 powder is dispersed in a solution in which an organosilica sol is dissolved in an organic solvent. (JP-A-8-67835) discloses a coating composition.
[0004]
[Problems to be solved by the invention]
Even in a coating composition prepared by mixing a photocatalyst-dispersed toner and an inorganic binder immediately before coating, the agglomeration and precipitation of anatase-type titania powder proceeds, so that the coating properties and coating properties are not stabilized. The aggregation precipitation is caused by the fact that the zeta potential of the anatase type titania powder is in the range of 4.5 to 6.0 and overlaps with the pH of the inorganic binder adjusted for storage stabilization of 3 to 6.5.
[0005]
Accordingly, the present inventors have proposed to add a part of the organoalkoxysilane as a binder component to the photocatalyst-dispersed toner in advance in order to prevent aggregation and precipitation of the anatase-type titania powder (Japanese Patent Laid-Open No. 2002-105357). ). When the organoalkoxysilane added to the photocatalyst-dispersed toner covers the surface of the anatase titania powder, the zeta potential of the powder surface deviates from the pH value of the inorganic binder, and as a result, even when mixed with the inorganic binder, the anatase titania powder It is presumed that coagulation and precipitation of is suppressed.
[0006]
[Means for Solving the Problems]
The present invention was devised to further improve the photocatalyst coating composition introduced in the prior application / Japanese Patent Application Laid-Open No. 2002-105357, and the surface of the anatase titania powder is modified by partially hydrolyzing the alkoxy group of the organoalkoxysilane. An object of the present invention is to further improve the dispersibility of anatase-type titania powder even in a photocatalyst-dispersed toner by reacting with an OH group.
[0007]
In order to achieve the object, the photocatalyst-dispersed toner of the present invention comprises an anatase-type titania powder and an organoalkoxysilane mixed with a small amount of water in a mixed solvent of isopropanol and butylcellosolve and coated with an organoalkoxysilane partially hydrolyzed by addition of water. The anatase-type titania powder is dispersed. The amount of water to be added is selected in the range of 0.1 to 10% by mass, in which the organoalkoxysilane is partially hydrolyzed but the dehydration condensation reaction between the organoalkoxysilanes does not proceed.
[0008]
As the anatase type titania powder, a powder having a particle size of 5 to 200 nm is preferable, and it is blended at a ratio of 30 to 60% by mass. The organoalkoxysilane has the general formula R 1 Si (OR 2 ) 3 [R 1 is an alkyl group having 1 to 3 carbon atoms, vinyl group, 3,4-epoxycyclohexyl group, γ-glycidoxypropyl group or γ-mercapto. Propyl group, R 2 is an alkyl group or aryl group having 1 to 4 carbon atoms], and is blended at a ratio of 1 to 10% by mass.
[0009]
[Operation and embodiment]
The organoalkoxysilane blended in the photocatalyst-dispersed toner is adsorbed on the surface of the anatase type titania powder as it is, or simply dispersed in a solvent. Although the adsorbed organoalkoxysilane improves the dispersibility of the anatase-type titania powder, it cannot be said that the dispersibility is sufficient for long-term storage.
[0010]
In a system in which water is present, the alkoxy group of the organoalkoxysilane is partially hydrolyzed. Since the hydrolysis product binds to the OH group on the surface of the anatase type titania powder, the organoalkoxysilane adheres to the surface of the anatase type titania powder through this bond. Anatase-type titania powder has improved dispersibility due to adhesion of organoalkoxysilane, and is suspended in the photocatalyst-dispersed toner for a long time without aggregation and precipitation. As a result, a photocatalyst-dispersed toner having excellent storage stability can be obtained. Good dispersibility is maintained even after mixing with an inorganic binder.
[0011]
The adhesion amount of the organoalkoxysilane to the surface of the anatase-type titania powder can be controlled by the water addition amount of the photocatalyst-dispersed toner, and the improvement in dispersibility due to the adhesion of the organoalkoxysilane can be seen at a water addition amount of 0.1% by mass or more. As the amount of water added increases, the amount of organoalkoxysilane adhering to the surface of the anatase titania powder increases, and the dispersibility of the anatase titania powder improves. However, when an excessive amount of water exceeding 10% by mass is added, the hydrolysis product of the alkoxy group adhering to the surface of the anatase-type titania powder increases so that the photocatalytic activity is impaired. Excess water addition promotes dehydration condensation between the organoalkoxysilanes added to the photocatalyst-dispersed toner, and the ratio of hydrolysis products adhering to the surface of the anatase-type titania powder is reduced.
[0012]
Components other than water blended in the photocatalyst-dispersed toner are preferably determined as follows.
As the photocatalyst, anatase titania powder having a particle size of 5 to 200 nm, which has high photocatalytic activity and excellent chemical stability, is blended at a ratio of 30 to 60% by mass. A powder with a particle size of 5 nm is difficult to produce itself, and the photocatalytic activity is insufficient with a particle size of 200 nm. If the blending ratio of the anatase type titania powder is less than 30% by mass, there is no thixotropy and the particles settle quickly and become a hard cake, so that redispersion when using the toner becomes difficult. On the other hand, if the blending amount exceeds 60% by mass, the thixotropy becomes too high and the fluidity as a toner is impaired.
[0013]
The organoalkoxysilane has the general formula R 1 Si (OR 2 ) 3 [R 1 is an alkyl group, vinyl group, 3,4-epoxycyclohexyl group, γ-glycidoxypropyl group or γ-mercaptopropyl group, R 2 is The alkyl group or aryl group having 1 to 4 carbon atoms] is blended at a ratio of 1 to 10% by mass. In the organoalkoxysilane, the reaction between silanes is suppressed by the introduction of the organic functional group, and the ratio of adhesion to the surface of the anatase-type titania powder increases. In this respect, tetraalkoxysilane not only contributes to the dispersion of the anatase titania powder as a result of not only the hydrolysis proceeding excessively and adhering to the surface of the anatase titania powder but also the reaction between the silanes. Even in the case of organoalkoxysilane, when there are two or more organic functional groups, the amount of organic matter adhering to the surface of the anatase titania powder increases. When a photocatalytic coating film prepared from a dispersed toner of anatase-type titania powder to which an excessive amount of organic substance is attached is placed in a light irradiation environment, the organic substance is decomposed and the coating is choked in a short time. Therefore, only one organic functional group directly bonded to Si is used, and an alkyl group having 1 to 3 carbon atoms, a vinyl group, a 3,4-epoxycyclohexyl group, a γ-glycidoxypropyl group, or a γ-mercaptopropyl group. It is preferable to do.
[0014]
The compounding amount of the organoalkoxysilane is determined in the range of 1 to 10% by mass. When the blending amount is less than 1% by mass, no improvement in dispersibility is observed. Conversely, when the blending amount exceeds 10% by mass, the anatase-type titania powder has an excessively high surface coverage, and the photocatalytic activity after coating is extremely high. descend. The compounding amount of the organoalkoxysilane depends on the particle size of the anatase type titania powder. For example, 7 nm TiO 2 powder has a large surface area of about 300 m 2 / g, so that 8% by mass of organoalkoxysilane provides the greatest effect. A TiO 2 powder having a particle size of 20 nm has a surface area of about 50 m 2 / g, and is most effective when the amount of organoalkoxysilane is 3% by mass.
[0015]
As the solvent, a mixed solvent of isopropanol and butyl cellosolve is used. The mixing ratio is preferably isopropanol: 40 to 60% by mass and butyl cellosolve: 40 to 60% by mass. By adjusting the mixing ratio, the dispersibility of the anatase-type titania powder is improved, and the volatilization speed is appropriately controlled when the coating film is formed after the photocatalyst-dispersed toner is mixed with the binder. Is prevented from occurring.
The photocatalyst-dispersed toner is prepared by adding anatase-type titania powder to a mixed solvent of isopropanol / butyl cellosolve to which organoalkoxysilane and water are added, stirring with a stirrer, and then a flow rate of 1 liter into a horizontal mill in which the filled beads are maintained in a stirring state It is prepared by injecting at a rate of / min. If necessary, it is also possible to add colorants such as pigments and dyes, and additives such as thickeners.
[0016]
The inorganic binder that can be blended with the photocatalyst-dispersed toner includes those obtained by hydrolyzing and condensing alkoxysilane and / or organoalkoxysilane, silica-based, aluminum or alcohol-based colloidal silica mixed with the hydrolyzed condensate, aluminum Examples include those obtained by hydrolyzing and condensing an alkoxide, and alumina based in which water-based or alcohol-based colloidal alumina is blended with the hydrolyzed condensate. Silica-based and alumina-based materials can be mixed and used, and can be blended in both water-based and solvent-based ones. When imparting flexibility to the coating film, a binder blended with acrylic silicate or the like may be used.
[0017]
When preparing a paint from the photocatalyst-dispersed toner and the inorganic binder, the photocatalyst-dispersed toner and the inorganic binder are mixed at a blending ratio of 5 to 80% by mass of TiO 2 as a solid content. In order to obtain sufficient photocatalytic activity, a TiO 2 content of 5% by mass or more is necessary, but if an excessive amount of TiO 2 exceeding 80% by mass is contained, the adhesion of the coating film decreases. In mixing, an inorganic binder is gradually added to the sufficiently stirred photocatalyst-dispersed toner, followed by further stirring to form a coating material.
[0018]
The prepared paint is applied to the pretreated substrate by spraying, dipping, flow coating, roll coating, screen printing, electrostatic coating, or the like. After coating, a coating film having excellent adhesion to the substrate is formed by heating at 80 to 130 ° C. for 1 to 30 minutes. The thickness of the coating film varies depending on the type and application of the base material and cannot be determined unconditionally, but is usually adjusted in the range of 1 to 30 μm. Base materials to which the photocatalytic coating composition is applied include ordinary steel, plated steel plate, stainless steel plate, aluminum, copper, brass and other metals, cement, concrete, tile, slate plate, glass, stone and the like. Depending on the heating temperature, it can also be applied to organic materials such as plastic.
[0019]
【Example】
Preparation of Anatase Type Titania Powder Dispersed Toner 3% by weight of organoalkoxysilane and water were added to a mixed solvent of isopropanol: 50% by mass and butyl cellosolve: 50% by mass, and anatase type titania powder having a particle size of 20 nm was further added. The addition amount of the anatase type titania powder was set to a ratio of 40% by mass with respect to the entire coating material. A photocatalyst-dispersed toner was prepared by dispersing the mixture with a stirrer using a bead mill.
[0020]
Preparation of inorganic binder Water-based colloidal silica: 21.2 g (average particle size 5 to 20 nm, solid content 20 mass%, pH 3.0) and isopropanol colloidal silica 62.6 g (average particle size 5 to 20 nm, solid content 20 mass) %), 13.9 g of methyltrimethoxysilane was added, and the mixture was stirred at 30 ° C. for 5 hours to complete the hydrolysis. Next, a mixed solvent of isopropanol: 33% by mass and butyl cellosolve: 67% by mass was added to the hydrolyzate, and ammonia water was further added to adjust the pH to 4.5.
The obtained photocatalyst-dispersed toner and inorganic binder were mixed and stirred at a ratio such that the TiO 2 content in the solid content was 40% by mass, and filtered using a 50 μm mesh to form a paint.
[0021]
A paint was spray-coated on the pretreated SUS304 stainless steel substrate and heated at 200 ° C. for 20 minutes to form a coating film having a thickness of 10 μm. For comparison, a SUS304 stainless steel substrate was similarly coated using a paint prepared by mixing water-free photocatalyst-dispersed toner with an inorganic binder.
[0022]
The dispersibility of the prepared photocatalytic coating composition and the photocatalytic activity of the coating film were evaluated by the following methods.
(1) Dispersibility of photocatalyst coating composition The photocatalyst-dispersed toner and the inorganic binder were mixed to form a coating material, and the aggregation state of TiO 2 particles was investigated after one day. Dispersibility with a coating composition in which no tabs of 5 μm or more are detected as ○, a coating composition in which no tabs of 10 μm or more are detected but 5-10 μm are detected is Δ, and a coating composition in which tabs of 10 μm or more are generated is × Evaluated.
(2) Weight of salad oil remaining on the test piece after the salad oil was attached to the surface of the test piece with a photocatalytic activity adhesion amount of 0.2 mg / cm 2 on the coating film and irradiated with black light of 5 mW / cm 2 for 24 hours. Was measured, and the photocatalytic activity was evaluated using the weight reduction rate as the oil decomposition rate.
[0023]
As can be seen from the investigation results in Table 1, when a coating composition obtained from a water-free photocatalyst-dispersed toner added with an organoalkoxysilane is used, the dispersibility is good to some extent, but the photocatalytic activity is inferior. It was. In contrast, the coating composition obtained from the photocatalyst-dispersed toner according to the present invention has better dispersibility due to the effect of water addition, and the anatase-type titania powder is uniformly dispersed in the coating film, and the photocatalytic activity is also improved. It was further improved.
[0024]
【The invention's effect】
As described above, a small amount of water is added to the photocatalyst-dispersed toner containing anatase-type titania powder and organoalkoxysilane to partially hydrolyze the organoalkoxysilane, and an OH group on the surface of the anatase-type titania powder has an alkoxy group. When the hydrolysis product is reacted, aggregation and precipitation of the anatase-type titania powder is suppressed and dispersibility is improved. The coating composition prepared by blending this photocatalyst-dispersed toner with an inorganic binder is applied to the coating original plate while maintaining the excellent dispersion state of the anatase-type titania powder, and the photocatalytic activity of the anatase-type titania powder is efficient. It becomes a photocatalyst coating film that develops well.
Claims (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002350672A JP4227802B2 (en) | 2002-12-03 | 2002-12-03 | Photocatalyst dispersed toner |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002350672A JP4227802B2 (en) | 2002-12-03 | 2002-12-03 | Photocatalyst dispersed toner |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2004182838A JP2004182838A (en) | 2004-07-02 |
| JP4227802B2 true JP4227802B2 (en) | 2009-02-18 |
Family
ID=32752819
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2002350672A Expired - Fee Related JP4227802B2 (en) | 2002-12-03 | 2002-12-03 | Photocatalyst dispersed toner |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4227802B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5121169B2 (en) * | 2006-06-14 | 2013-01-16 | 株式会社日本触媒 | Organic solvent dispersion of inorganic-containing particles and inorganic-containing particles used in the dispersion |
-
2002
- 2002-12-03 JP JP2002350672A patent/JP4227802B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2004182838A (en) | 2004-07-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3348635B2 (en) | Coating composition, method for forming hydrophilic film, and hydrophilic film-coated article | |
| CN100572462C (en) | Antiadhesive high temperature layers | |
| JP3949175B2 (en) | Polyalkoxysiloxane compound, method for producing the same, and coating composition containing the same | |
| EP1017746B1 (en) | Hydrophilic materials and their method of preparation | |
| JPH05221640A (en) | Production of hydrophobic titanium oxide fine particle | |
| CN101525504A (en) | Photocatalytic self-cleaning film coating agent with self-layered isolation effect and preparation method thereof | |
| JP6961931B2 (en) | Metatitanic acid particles and their production methods, photocatalyst-forming compositions, photocatalysts, and structures | |
| JP2603291B2 (en) | Fine powder of silicone resin containing quaternary ammonium group | |
| JP2018168007A (en) | Metatitanic acid particle, production method of metatitanic acid particle, composition for photocatalyst formation, photocatalyst and structure | |
| JP2018094495A (en) | Titanium oxide particles and method for producing the same, composition for forming photocatalyst, photocatalyst and structure | |
| JP4409169B2 (en) | Paint containing colored pigment particles, substrate with visible light shielding film | |
| JP2002249705A (en) | Photocatalytic coating composition | |
| JP4456809B2 (en) | Photocatalyst coating composition | |
| JP4227802B2 (en) | Photocatalyst dispersed toner | |
| JP2717167B2 (en) | Coating composition | |
| JP2000290528A (en) | Lustrous material, coating composition and coated item | |
| JPH10324838A (en) | Pigment dispersion composition and coating composition | |
| JP3499525B2 (en) | Photocatalytic coating composition | |
| JP2009209250A (en) | Photocatalyst coating film forming composition, photocatalyst coating film, and forming method of photocatalyst coating film | |
| JP2003026959A (en) | Inorganic coating | |
| JP2010043159A (en) | Method for producing titanium oxide dispersion and titanium oxide film | |
| JP2005179472A (en) | Highly corrosionproof zinc powder-containing coating composition | |
| JP2002308664A (en) | Inorganic based curable composition and inorganic coating material | |
| JP2000212473A (en) | Coating composition | |
| JP2005113023A (en) | Photocatalyst-containing silicon composition |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20050712 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A821 Effective date: 20070416 |
|
| RD03 | Notification of appointment of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7423 Effective date: 20070416 |
|
| RD04 | Notification of resignation of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7424 Effective date: 20070416 |
|
| RD03 | Notification of appointment of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7423 Effective date: 20070426 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A821 Effective date: 20070426 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20080811 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20080826 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20081118 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20081201 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111205 Year of fee payment: 3 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20141205 Year of fee payment: 6 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| LAPS | Cancellation because of no payment of annual fees |