JP3814653B2 - Aqueous coating solution for forming photocatalyst layer, method for producing metal plate having photocatalyst layer, and metal plate having photocatalyst layer - Google Patents
Aqueous coating solution for forming photocatalyst layer, method for producing metal plate having photocatalyst layer, and metal plate having photocatalyst layer Download PDFInfo
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- JP3814653B2 JP3814653B2 JP2002128414A JP2002128414A JP3814653B2 JP 3814653 B2 JP3814653 B2 JP 3814653B2 JP 2002128414 A JP2002128414 A JP 2002128414A JP 2002128414 A JP2002128414 A JP 2002128414A JP 3814653 B2 JP3814653 B2 JP 3814653B2
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- photocatalyst layer
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- 239000011248 coating agent Substances 0.000 title claims description 48
- 238000000576 coating method Methods 0.000 title claims description 48
- 229910052751 metal Inorganic materials 0.000 title claims description 46
- 239000002184 metal Substances 0.000 title claims description 46
- 239000011941 photocatalyst Substances 0.000 title claims description 31
- 238000004519 manufacturing process Methods 0.000 title claims description 9
- 229910010413 TiO 2 Inorganic materials 0.000 claims description 46
- 229910019142 PO4 Inorganic materials 0.000 claims description 28
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 28
- 239000010452 phosphate Substances 0.000 claims description 28
- 239000007788 liquid Substances 0.000 claims description 16
- 239000002245 particle Substances 0.000 claims description 14
- 239000002243 precursor Substances 0.000 claims description 12
- 150000003839 salts Chemical class 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 6
- 150000007524 organic acids Chemical class 0.000 claims description 6
- ILRRQNADMUWWFW-UHFFFAOYSA-K aluminium phosphate Chemical compound O1[Al]2OP1(=O)O2 ILRRQNADMUWWFW-UHFFFAOYSA-K 0.000 claims description 5
- 229910017604 nitric acid Inorganic materials 0.000 claims description 5
- -1 oxy titanium oxalate ammonium Chemical compound 0.000 claims description 5
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 4
- 230000015572 biosynthetic process Effects 0.000 claims description 2
- FUFJGUQYACFECW-UHFFFAOYSA-L calcium hydrogenphosphate Chemical compound [Ca+2].OP([O-])([O-])=O FUFJGUQYACFECW-UHFFFAOYSA-L 0.000 claims description 2
- 238000010304 firing Methods 0.000 claims description 2
- QQFLQYOOQVLGTQ-UHFFFAOYSA-L magnesium;dihydrogen phosphate Chemical compound [Mg+2].OP(O)([O-])=O.OP(O)([O-])=O QQFLQYOOQVLGTQ-UHFFFAOYSA-L 0.000 claims description 2
- BECVLEVEVXAFSH-UHFFFAOYSA-K manganese(3+);phosphate Chemical compound [Mn+3].[O-]P([O-])([O-])=O BECVLEVEVXAFSH-UHFFFAOYSA-K 0.000 claims description 2
- 150000003013 phosphoric acid derivatives Chemical class 0.000 claims description 2
- LKCUKVWRIAZXDU-UHFFFAOYSA-L zinc;hydron;phosphate Chemical compound [Zn+2].OP([O-])([O-])=O LKCUKVWRIAZXDU-UHFFFAOYSA-L 0.000 claims description 2
- 235000005985 organic acids Nutrition 0.000 claims 1
- 230000001699 photocatalysis Effects 0.000 description 30
- 239000010410 layer Substances 0.000 description 24
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 13
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 12
- 239000000243 solution Substances 0.000 description 11
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 10
- 239000007864 aqueous solution Substances 0.000 description 10
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 8
- 229910052782 aluminium Inorganic materials 0.000 description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 8
- VBIXEXWLHSRNKB-UHFFFAOYSA-N ammonium oxalate Chemical compound [NH4+].[NH4+].[O-]C(=O)C([O-])=O VBIXEXWLHSRNKB-UHFFFAOYSA-N 0.000 description 8
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 238000002156 mixing Methods 0.000 description 7
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 6
- 239000012298 atmosphere Substances 0.000 description 6
- 235000019253 formic acid Nutrition 0.000 description 6
- 239000010959 steel Substances 0.000 description 6
- 229910021529 ammonia Inorganic materials 0.000 description 5
- 239000010419 fine particle Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 4
- 235000006408 oxalic acid Nutrition 0.000 description 4
- 239000003973 paint Substances 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 3
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 3
- 229910001297 Zn alloy Inorganic materials 0.000 description 3
- FJMNNXLGOUYVHO-UHFFFAOYSA-N aluminum zinc Chemical compound [Al].[Zn] FJMNNXLGOUYVHO-UHFFFAOYSA-N 0.000 description 3
- 238000000137 annealing Methods 0.000 description 3
- 238000005452 bending Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 238000000746 purification Methods 0.000 description 3
- 239000004408 titanium dioxide Substances 0.000 description 3
- 239000011701 zinc Substances 0.000 description 3
- 229910052725 zinc Inorganic materials 0.000 description 3
- BNGXYYYYKUGPPF-UHFFFAOYSA-M (3-methylphenyl)methyl-triphenylphosphanium;chloride Chemical compound [Cl-].CC1=CC=CC(C[P+](C=2C=CC=CC=2)(C=2C=CC=CC=2)C=2C=CC=CC=2)=C1 BNGXYYYYKUGPPF-UHFFFAOYSA-M 0.000 description 2
- IKHGUXGNUITLKF-UHFFFAOYSA-N Acetaldehyde Chemical compound CC=O IKHGUXGNUITLKF-UHFFFAOYSA-N 0.000 description 2
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910002651 NO3 Inorganic materials 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- CDQFODAJQFUTJR-UHFFFAOYSA-M [NH4+].[O-]C(=O)C(=O)O[Ti] Chemical compound [NH4+].[O-]C(=O)C(=O)O[Ti] CDQFODAJQFUTJR-UHFFFAOYSA-M 0.000 description 2
- 230000000844 anti-bacterial effect Effects 0.000 description 2
- 239000004566 building material Substances 0.000 description 2
- 239000004568 cement Substances 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000004332 deodorization Methods 0.000 description 2
- 230000001877 deodorizing effect Effects 0.000 description 2
- SOCTUWSJJQCPFX-UHFFFAOYSA-N dichromate(2-) Chemical compound [O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O SOCTUWSJJQCPFX-UHFFFAOYSA-N 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000010828 elution Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 239000003822 epoxy resin Substances 0.000 description 2
- 239000011737 fluorine Substances 0.000 description 2
- 229910052731 fluorine Inorganic materials 0.000 description 2
- 239000010440 gypsum Substances 0.000 description 2
- 229910052602 gypsum Inorganic materials 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- GVALZJMUIHGIMD-UHFFFAOYSA-H magnesium phosphate Chemical compound [Mg+2].[Mg+2].[Mg+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O GVALZJMUIHGIMD-UHFFFAOYSA-H 0.000 description 2
- 239000004137 magnesium phosphate Substances 0.000 description 2
- 229960002261 magnesium phosphate Drugs 0.000 description 2
- 229910000157 magnesium phosphate Inorganic materials 0.000 description 2
- 235000010994 magnesium phosphates Nutrition 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- YPJKMVATUPSWOH-UHFFFAOYSA-N nitrooxidanyl Chemical compound [O][N+]([O-])=O YPJKMVATUPSWOH-UHFFFAOYSA-N 0.000 description 2
- 239000000049 pigment Substances 0.000 description 2
- 229920000647 polyepoxide Polymers 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- XNDZQQSKSQTQQD-UHFFFAOYSA-N 3-methylcyclohex-2-en-1-ol Chemical compound CC1=CC(O)CCC1 XNDZQQSKSQTQQD-UHFFFAOYSA-N 0.000 description 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 229910001335 Galvanized steel Inorganic materials 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 241000208125 Nicotiana Species 0.000 description 1
- 235000002637 Nicotiana tabacum Nutrition 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- IOVCWXUNBOPUCH-UHFFFAOYSA-M Nitrite anion Chemical compound [O-]N=O IOVCWXUNBOPUCH-UHFFFAOYSA-M 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 1
- 239000010883 coal ash Substances 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 238000009500 colour coating Methods 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000005238 degreasing Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000008397 galvanized steel Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000002346 layers by function Substances 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 229940005654 nitrite ion Drugs 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- GEVPUGOOGXGPIO-UHFFFAOYSA-N oxalic acid;dihydrate Chemical compound O.O.OC(=O)C(O)=O GEVPUGOOGXGPIO-UHFFFAOYSA-N 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000008213 purified water Substances 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 150000003377 silicon compounds Chemical class 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- BFKJFAAPBSQJPD-UHFFFAOYSA-N tetrafluoroethene Chemical group FC(F)=C(F)F BFKJFAAPBSQJPD-UHFFFAOYSA-N 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
- 239000005029 tin-free steel Substances 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 150000003609 titanium compounds Chemical class 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 229910000349 titanium oxysulfate Inorganic materials 0.000 description 1
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 description 1
- JUWGUJSXVOBPHP-UHFFFAOYSA-B titanium(4+);tetraphosphate Chemical class [Ti+4].[Ti+4].[Ti+4].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O JUWGUJSXVOBPHP-UHFFFAOYSA-B 0.000 description 1
- 230000037303 wrinkles Effects 0.000 description 1
Landscapes
- Chemical Treatment Of Metals (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Laminated Bodies (AREA)
- Catalysts (AREA)
- Paints Or Removers (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、表面に二酸化チタンを含有し光触媒機能を有する被膜を形成した金属部材を製造するための光触媒層形成用水性コーティング液、光触媒層を有する金属板の製造方法及び光触媒層を有する金属板に関する。
【０００２】
【従来の技術】
二酸化チタン（以下、単にTiO2と表記する）は優れた光触媒機能を有するので、その微粒子を基体表面に塗布して付着汚れの分解、NOX、SOXの分解による大気の浄化、抗菌、脱臭、などの用途に利用する提案が数多くされている。かかる提案は金属板を基体とする場合にもなされており、種々の塗料にTiO2を混じて塗布・焼き付けた光触媒機能を有する金属板も提案されている。
【０００３】
このような用途に適する塗料としては金属板への密着性の点からは有機高分子を多く含むものが適する。しかし、かかる塗料は、TiO2が紫外線の照射を受けたとき発生する光触媒機能により酸化、分解しTiO2粒子を保持できなくなるという問題がある。そのため、たとえば特許第2918787公報にはセメント、セッコウを、特許第3027739公報にはフッ素系ポリマー、シリコン系ポリマー、ケイ素化合物を光触媒作用により分解しにくいバインダーとして用いるという提案がなされている。
【０００４】
しかしながら、これら従来の方法には以下のような問題がある。まずバインダーとしてセメントおよび石膏は金属板に薄く均一に塗布することが困難であり、仮に塗布しても僅かな曲げ加工により被膜が破壊され剥離する。シリコン系ポリマーは、金属板への密着力が劣るためエポキシ樹脂などの下塗りが必要であり、その上に直接TiO2を含有させた光触媒機能層を形成すると、下塗りのエポキシ樹脂がTiO2の光触媒機能により酸化、分解しTiO2粒子を保持できなくなるという問題があり、そのため光触媒機能を遮断する中塗り層が必要になるという問題がある。
【０００５】
また、TiO2粒子の光触媒機能は比較的微弱であるため、例えばNOXの除去や室内の脱臭などの環境浄化を目的とする場合、十分な効果を得るためには広い面積を必要とする。そのためには、カラー鋼板やカラーアルミニウムのように帯状の金属板に高速で連続的に塗布・乾燥する生産工程を採ることが望ましいが、シリコン系樹脂塗膜は加工性が悪くわずかな曲げ加工で剥離してしまうため、高速で連続的に塗布・乾燥する生産工程はいまだ実用化されていない。
【０００６】
特開平10-152368号公報には、道路の側壁や建築構造体に石炭灰と第１りん酸アルミニウムを主成分とする無機系バインダーを利用してTiO2粒子を担持させ、NOXやSOXの浄化の有効なセラミックス成形物とする方法が提案されている。しかし、この方法は乾燥および焼成に１時間以上の長時間を要するため生産性が低く金属薄板への連続処理には適用できない。また、このようにして形成された被膜は、TiO2粒子と環境雰囲気との接触面積が小さいため、十分な光触媒活性を保有させるためには、形成された被膜の表面を研磨紙で研削する必要もある。
【０００７】
これらの方法に代えて、特公平6-99813号公報に提案されているりん酸塩に重クロム酸塩および界面活性剤を配合した処理液を用い、これにTiO2粒子を担持させて鋼板に塗布し焼き付けるという手段も考えられる。しかし、このような手段は重クロム酸塩が有害な６価クロムを含むという問題があり実用的ではない。
【０００８】
上記の他に、TiO2の光触媒性機能により容易に分解せず、かつ加工性のよい四フッ化エチレン系のフッ素樹脂塗料を用いてTiO2の担体とすることも考えられるが、この場合はTiO2粒子が樹脂により被覆されて大気と接触できなくなるため、光触媒機能を発揮できなくなるという問題がある。
【０００９】
【発明が解決しようとする課題】
本発明は、金属、特に大量生産される金属板上に光触媒性機能を有し、TiO2の光触媒機能によって容易に破壊されず、かつ加工性および密着性のよい被膜を形成できる手段を提案する。本発明は、同時に、表面に光触媒層を有する金属板を経済的かつ、公害の発生なく生産できる手段及び光触媒層を有する金属板を提案する。具体的には、上記目的を達するための光触媒層形成用水性コーティング液、光触媒層を有する金属板の製造方法及びそれにより製造された光触媒層を有する金属板を提案する。
【００１０】
【課題を解決するための手段】
本発明者は、特開2001-73169号公報、特願2001-83417において、TiO2粒子を分散したりん酸アルミニウム、りん酸マグネシウムなどの有機溶媒を含有しないりん酸塩水溶液を金属板に塗布し350℃以上の温度で焼き付けることにより、加工性、密着性、光触媒性の優れた表面被膜が形成することを提案している。本発明は、これらの提案をさらに進めたものであって、TiO2前駆体を含むTiO2粒子等を含有するりん酸塩水溶液にさらに適量の硝酸、有機酸、及びこれらの塩の1種以上を含有するコーティング液とし、これを金属板上に塗布、焼き付けることによって、被膜の密着性および光触媒性機能を増大し得ることを知見して、本発明を完成した。
【００１１】
本発明の光触媒層形成用水性コーティング液は、質量比で、PO4に換算して水溶性りん酸及び／又は水溶性りん酸塩を合計量で100部、TiO2に換算してTiO2粒子及び／又はTiO2前駆体の１種以上を合計量で140〜700部、NO3に換算して硝酸及び／又はその塩を合計量で5〜50部、有機酸及びそれらの塩から選ばれた１種以上を合計量で 5 〜 400 部の割合で含有するものである。
【００１２】
前記光触媒層形成用水性コーティング液において、TiO2前駆体はオキシ蓚酸チタンアンモニウムとするのがよい。さらに、水溶性りん酸塩は第一りん酸アルミニウム、第一りん酸マグネシウム、第一りん酸マンガン、第一りん酸亜鉛及び第一りん酸カルシウムから選んだいずれか１種又はこれらの混合物とするのがよい。上記、光触媒層形成用水性コーティング液には、さらにその含有硝酸根100部に対して、アンモニアを20〜35部含有させることができる。
【００１３】
上記の光触媒層形成用コーティング液を、金属板表面に焼付後の厚さが0.3〜9g/m2になるように塗布した後、350〜700℃の雰囲気温度で焼成する工程を1回以上行うことよって光触媒層を有する金属板を製造することができる。
【００１４】
【発明の実施の形態】
本発明の光触媒層形成用コーティング液は、広く金属板に塗布され乾燥・焼付けされて硬質で加工性がよくかつ光触媒特性のよい被膜、特にりん酸塩系被膜を形成するものである。そのため、特定の組成を有するように以下に示すようにして調整される。なお、ここにいうりん酸塩系被膜とは、金属上に塗布した第１りん酸塩を主成分とする水溶液が加熱されことによって脱水、縮合して形成される耐火物系の不溶性被膜をいい、顔料粒子等を含むことができるもので、通常の鉄や亜鉛の表面に80℃以下の水溶液中で処理される塗装下地のための被膜とは異なるものである。
【００１５】
まず、りん酸塩水溶液の調整を行う。その調整は、りん酸水溶液にアルミニウム、マグネシウム、マンガン、カルシウム、亜鉛等の金属の酸化物、水酸化物、あるいは炭酸塩等の金属塩を配合することによって行うのがよい。金属塩のりん酸に対する配合量は、モル比でりん酸との反応により第一りん酸塩が生成するに必要量の1.2〜0.8の範囲にあればよい。配合量が0.8未満の場合は水に不溶性の被膜を生成するのに長時間を要するので好ましくなく、1.2を超えると不溶性の粒子が発生し易くなるため表面状態が劣化する。なお、りん酸塩水溶液のりん酸塩濃度は、質量比でPO4に換算して1〜15%、好ましくは、3〜12%とするのがよい。
【００１６】
上記により調整されたりん酸塩水溶液にTiO2粒子及び／又はTiO2前駆体の１種以上を添加する。これらの配合量は形成される被膜の光触媒機能及び形成された被膜の硬度等によって定めるのがよい。一般にTiO2の微粒子、またはゾルを用いる場合には、PO4に対するTiO2の比を比較的小さく、これに対し、蓚酸チタニールアンモニウムなどのTiO2前駆体を用いる場合には前記比を大きく取ることができる。
【００１７】
具体的には、TiO2の微粒子、またはゾルの1種以上を添加する場合は、PO4に換算した水溶性りん塩及び／又は水溶性りん酸塩の合計量で100部に対し、これらをTiO2換算分で合計140〜250部、好ましくは150〜200部となるようにする。TiO2換算分が140部を下回ると光触媒性能が不十分となり、一方、250部を超えると生成した被膜の硬度が低くなって疵がつき易くなり好ましくない。特に、150〜200部の範囲が光触媒性能および被膜硬度の点から見が好適である。なお、りん酸塩水溶液に添加される酸化チタンは粉末、ゾルのいずれでも良い。特に結晶子径35nm以下、比表面積（BET）50m2/g以上の微細な粉末または同等のゾル・スラリーが好ましい。
【００１８】
TiO2の前駆体も利用できる。前駆体としては硫酸チタニール、塩化チタン、水和りん酸チタン化合物、蓚酸チタニールアンモニウム、チタンのアルコキシド、キレート、アセテートなどの有機チタン化合物で250℃以上の加熱によりTiO2を生成する化合物が利用可能である。中でもオキシ蓚酸チタンアンモニウム水溶液を用いる場合は、バインダーであるPO4に対してより多くのTiO2が存在できるようにすることができるので優れた光触媒性を発揮する光触媒層を有する金属板の製造が可能になる。例えば、PO4に換算した水溶性りん塩及び／又は水溶性りん酸塩の合計量で100部に対し、オキシ蓚酸チタンアンモニウム水溶液をTiO2換算分で200〜700部とすることができる。なお、これらTiO2の前駆体とTiO2の微粒子またはゾルとは共存させることもできる。
【００１９】
上記混合液には、りん酸塩(PO4換算)100部に対しNO3に換算して5〜50部の硝酸またはその塩を添加する。これにより焼き付けにより生成する被膜の密着性が向上することができる。その効果は、りん酸塩(PO4換算)100部に対し5部以上の添加から認められ50部でほぼ飽和する。りん酸塩(PO4換算)100部に対し10〜30部とするのが好ましい。薬品としては硝酸アルミニウムの9水塩、すなわちAl(NO3)3・9H2Oが市販されているので好適に利用できる。
【００２０】
上記により調整された光触媒層形成用水性コーティング液には、さらに蓚酸、蟻酸などの有機酸、及びこれらの塩から選んだ１種以上を質量比でりん酸塩（PO4換算）100部に対し合計で5〜400部、好ましくは60〜270部含有するように調整することができる。この調整は、上記混合液に有機酸を添加することによって行われる。これにより被膜の金属との密着性、耐磨耗性、光触媒機能をさらに増大することができる。
【００２１】
上記有機酸としては、蟻酸を選択した場合は、特にNOX除去効果の向上が認められる。この効果はりん酸塩100部（PO4換算）に対し5部以上配合した場合に現われる。しかし、70部を超えると被膜の硬度が低下する。したがって、蟻酸の配合量は5〜70部とするのがよい。蓚酸を選択した場合は、被膜の密着性および耐摩耗性の向上に効果が認められる。その配合量は質量比でりん酸塩100部（PO4換算）に対し50〜300部とするのがよい。上記向上効果は50部未満では認められず、300部を超えると被膜の硬度が低下するからである。100〜250部が好適である。なお、上記配合においてTiO2前駆体として蓚酸塩、蓚酸チタニールアンモニウムを用いた場合にはそれに含まれるシュウ酸は有機酸の塩に含める。また、上記蟻酸、蓚酸、蓚酸チタニールアンモニウムなどはそれぞれ上記適正配合範囲内で共存させることができる。
【００２２】
また、TiO2前駆体として蓚酸チタニールアンモニウムを用いた場合は、焼付け過程において分解してアンモニアを発生するので連続カラー塗装ラインの脱臭装置において硝酸根から発生するNOXをN2とH2Oとに分解してNOXの発生を防止できるので好ましい。この蓚酸チタニールアンモニウムに代えて、処理液中の硝酸又は硝酸塩中の硝酸根100部に対し20〜35部のアンモニア及び／又はアンモニウム塩を配合することもできる。ただし、アンモニアの配合により処理液のpHが高くなると形成する被膜の下地金属との密着性が低下するのでアンモニアの配合量は処理液のpHが3.5以下、好ましくは2.0以下を維持するよう制御すべきである。
【００２３】
本発明の光触媒層形成用コーティング液は、上記の組成を有するものであるが、これには着色顔料を添加して、製品である光触媒層を有する金属板の意匠性を向上することができる。また、適量のワックス等の潤滑剤を添加して製品のロール成形性を向上することができる。その他、ロールコーターで塗布し易いように処理液の粘度を上昇させる増粘材を本発明の目的を損なわない範囲で添加することができる。
【００２４】
上記の光触媒層形成用コーティング液は、鋼板、アルミニウム板等の金属板の表面に塗布・焼き付けされて光触媒層を有する金属板の製造に利用される。金属板はいかなるもでもよいが、アルミニウム板、55%アルミニウムー亜鉛合金めっき鋼板などのアルミニウム−亜鉛合金めっき鋼板、亜鉛めっき鋼板、又はステンレス鋼板などとするのがよい。これらは何れも高度な耐食性を有し、屋外で用いる高耐食性建材とすることができる。なお、屋内用途の場合は、クロムめっきテインフリースチールや一般冷延鋼板等のやや耐候性に劣るものも使用し得る。塗布・焼き付けの手段は特に問わない。たとえば、公知のカラー鋼板やカラーアルミニウム板の製造ラインを用いることができ、ライン速度10〜150m/minの２コート２ベークの連続塗装焼き付け用の設備が好適に利用できる。
【００２５】
被膜の形成量は、乾燥重量で1〜15g/m2の範囲とするのがよい。付着量が1g/m2以下の場合は超親水性以外の光触媒機能が得られにくく、また15g/m2を越えると粉状あるいは疵が付き易い柔らかな被膜しか得られず曲げ加工性も低くなるからである。
【００２６】
上記被膜の形成に当たっては、１回当たりの塗布量が焼付後の厚さで0.3〜9g/m2になるように塗布した後、焼成する工程を2回以上行う２コート−２ベーク法を採用するのがよい。1回当たりの塗布量が9g/m2を越えると粉状あるいは疵が付き易い柔らかな被膜しか得られず曲げ加工性も低くなるからである。この場合第１層と第２層の処理液は本発明の範囲内の組成であれば同一である必要はない。この２コート−２ベーク法により光触媒性を発揮できる十分な厚さの被膜を形成させることができる。
【００２７】
焼き付け温度はりん酸系被膜の形成のために用いられる焼き付け温度でよく、たとえば、熱風炉を用いて表面の光触媒層が250℃以上にに達するように350℃以上の雰囲気でコーティング液を塗布した表面を加熱するのがよい。なお、焼き付け雰囲気温度が350℃以下ではりん酸塩の被膜が大気中で吸湿性を示し、700℃以上の雰囲気では亜鉛系めっき層の溶解やアルミニウム板の軟化が起こるため好ましくない。２コート２ベークの連続塗装焼き付け用の設備においては一般に下塗り用の第１塗装焼き付け炉は温度が低く350℃以上に昇温出来ない場合でも第２層を塗布し焼き付けを350℃以上の雰囲気中で焼き付ければ全体として吸湿性がなく光触媒機能の優れた被膜が得られる。
【００２８】
【実施例１】
質量比で結晶子径6nmのアナターゼ型TiO2粉末{テイカ（株）TKP‐101}：10ｇ、りん酸マグネシウム：5ｇ、硝酸アルミニウム9水塩：2.5ｇ、シュウ酸2水塩：12ｇ、蟻酸：2ｇ、水イオン交換水：60ｇからなる水系処理液を光触媒層形成用コーティング゛液として準備した。これを厚さ0.35mmの55%アルミニウム−亜鉛合金めっき板AZ150にバーコーターで塗布し400℃に保持した大気雰囲気炉中で70ｓ間焼き付け、乾燥膜厚1.9g/m2での1回焼付け板を得た。この1回焼付け板を冷却した後、その上にさらに上記処理液を前回と同一条件で塗布・焼き付けし、乾燥膜厚が合計で3.5g/m2の塗装板とした。得られた塗装板は直径5mmの丸棒に180°折り曲げても内側が全く剥離せず、被膜の密着性は良好であった。
【００２９】
【実施例２】
シュウ酸チタニールアンモニウム水溶液100 g（TiO2換算5g）に結晶子径15nmのアナターゼ型TiO2粉末（テイカ（株）TKP102）20g、第１りん酸アルミニウム5g、硝酸アルミニウム9水塩1.5g、蟻酸1.6gを配合した水系処理液を光触媒層形成用コーティング゛液として準備した。これを厚さ1.0mmのA5052アルミニウム板に塗布し350℃に保持した大気雰囲気炉中で70ｓ間焼き付けし、乾燥膜厚2.1g/m2の被膜を生成させた後、さらに上記処理液を塗布し、450℃で７0秒焼き付けて乾燥膜厚が合計で6.７g/m2の塗装板を得た。得られた塗装板は、直径5mmの丸棒に180°折り曲げても内側が全く剥離せず良好な被膜密着性を示した。
【００３０】
上記実施例１、２により得られた塗装金属板について光触媒特性の測定を行った。実施例1の塗装金属板について水の接触角は1.8°、実施例２の塗装金属板について水の接触角は0°であった。表面積49cm2に調整した各塗装金属板サンプルを0.5リットルのガラス容器に入れたのち、アセトアルデヒド濃度100ppmの空気を注入し、直ちに紫外線強度が1mw/cm2のブラックライトの光を照射し10min分ごとの濃度を測定し脱臭性能の指標とした。脱臭性能は実施例１の場合、30min後、3.8ppm、60min後に0.3ppmに達し、実施例２の場合、20分後に0ppmに達した。
【００３１】
また、脱NOX性能を資源環境技術研究所が作成したTR原案に準じて測定した。すなわち、石英製窓の下5mmの位置でブラックライトが10W/m2以下の照度で照射されるように幅5cm、長さ10cmの試験片を容器に入れ露点25℃、1.0ppmのNOガスを3l/min（12m/min）の流量で5ｈ通入した。試験したサンプルは精製水に浸漬して硝酸イオンおよび亜硝酸イオン濃度を測定しNOX溶出量を算定した。その結果、実施例１の場合、溶出量は14.3μモル、実施例２の場合18.5μモルであった。
【００３２】
上記実施例から明らかなように、本発明の光触媒活性を有する金属部材は、屋外で使用される種々の部材、例えば高速道路の防音壁や建物のサイディング等の外装材に利用した場合超親水性および汚染物質の分解により常に清浄であって清掃の必要が無く大気中のNOXの除去に役立てることができる。
【００３３】
また、例えば屋内の壁やブラインドのスラットに用いれば悪臭の除去やいわゆるシックハウスの原因とされている内装建材の接着剤から発生するホルムアルデヒドなどを効果的に除去し得る。さらに、タバコの煙によるやにの付着防止、防カビ、抗菌にも有効である。さらに本発明の光触媒活性を有する金属部材は、高温で焼き付けることによって製造されるので、室内で使用されたとき溶剤等の発生はまったくない。
【００３４】
【発明の効果】
本発明は金属板上にりん酸塩系焼き付け被膜を形成させ、それを介してアナターゼ型２酸化チタン微粒子を担持させる構造としたので金属板への密着性および加工性がよく、しかも光触媒性が有効かつ長時間にわたって発揮されるプレコート金属板を製造することができる。そしてそれを利用して製造された金属部材は、優れた光活性触媒機能をもち、屋内外の各種の構造物等に用いて生活環境の浄化に役立てることができる。また基板として5182や5052などの高強度アルミニウム板を用いた場合は 塗膜の焼き付け温度が焼きなまし温度と一致しているので脱脂後本処理液を塗布して焼き付けることにより焼きなまし工程を省くこともできる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aqueous coating solution for forming a photocatalyst layer for producing a metal member containing titanium dioxide on the surface and having a photocatalytic function, a method for producing a metal plate having a photocatalyst layer, and a metal plate having a photocatalyst layer About.
[0002]
[Prior art]
Titanium dioxide (hereinafter simply referred to as TiO 2 ) has an excellent photocatalytic function, so its fine particles can be applied to the substrate surface to decompose adhering dirt, clean up the atmosphere by decomposing NO X and SO X , antibacterial, and deodorizing. There have been many proposals for use in applications such as. Such a proposal has been made even when a metal plate is used as a base, and a metal plate having a photocatalytic function in which various paints are mixed and coated with TiO 2 has been proposed.
[0003]
As a paint suitable for such an application, a paint containing a large amount of an organic polymer is suitable from the viewpoint of adhesion to a metal plate. However, such a coating material has a problem that TiO 2 is oxidized and decomposed by the photocatalytic function generated when the TiO 2 is irradiated with ultraviolet rays and cannot hold the TiO 2 particles. For this reason, for example, Japanese Patent No. 2918787 proposes cement and gypsum, and Japanese Patent No. 3027739 proposes to use a fluorine-based polymer, a silicon-based polymer, and a silicon compound as a binder that is not easily decomposed by photocatalytic action.
[0004]
However, these conventional methods have the following problems. First, cement and gypsum as a binder are difficult to apply thinly and uniformly on a metal plate, and even if temporarily applied, the coating is broken and peeled off by slight bending. Silicon-based polymer, it is necessary undercoat such as an epoxy resin for adhesion to the metal plate is poor, to form a photocatalytic functional layer containing a directly TiO 2 thereon, the epoxy resin is TiO 2 subbing photocatalyst There is a problem that it is oxidized and decomposed depending on the function, and it becomes impossible to hold the TiO 2 particles. Therefore, there is a problem that an intermediate coating layer that interrupts the photocatalytic function is required.
[0005]
Further, since the photocatalytic function of TiO 2 particles is relatively weak, for example, for the purpose of environmental purification such as removal of NO x and indoor deodorization, a large area is required to obtain a sufficient effect. For this purpose, it is desirable to adopt a production process in which a strip-shaped metal plate, such as a color steel plate or color aluminum, is continuously applied and dried at high speed. Since it peels off, the production process of applying and drying continuously at high speed has not been put into practical use yet.
[0006]
In Japanese Patent Laid-Open No. 10-152368, side walls of roads and building structures are loaded with TiO 2 particles using an inorganic binder mainly composed of coal ash and primary aluminum phosphate, and NO X or SO X There has been proposed a method for producing a ceramic molded article effective for purification of the above. However, this method requires a long time of 1 hour or more for drying and firing, so the productivity is low and it cannot be applied to continuous processing on a metal thin plate. In addition, since the coating formed in this way has a small contact area between the TiO 2 particles and the environmental atmosphere, it is necessary to grind the surface of the formed coating with abrasive paper in order to retain sufficient photocatalytic activity. There is also.
[0007]
Instead of these methods, a treatment liquid in which dichromate and a surfactant are blended with phosphate proposed in Japanese Patent Publication No. 6-99813 is used, and TiO 2 particles are supported on this to a steel plate. A means of applying and baking can also be considered. However, such a measure is not practical due to the problem that dichromate contains harmful hexavalent chromium.
[0008]
In addition to the above, not easily decomposed by the photocatalytic function of the TiO 2, and it is conceivable to support the TiO 2 with a workability good tetrafluoroethylene-based fluorine resin paint, in this case There is a problem that the photocatalytic function cannot be exhibited because the TiO 2 particles are coated with the resin and cannot be brought into contact with the atmosphere.
[0009]
[Problems to be solved by the invention]
The present invention proposes means capable of forming a film having a photocatalytic function on a metal, particularly a mass-produced metal plate, which is not easily destroyed by the photocatalytic function of TiO 2 and has good workability and adhesion. . The present invention proposes a metal plate having a photocatalyst layer and means for producing a metal plate having a photocatalyst layer on its surface economically and without causing pollution. Specifically, an aqueous coating solution for forming a photocatalyst layer for achieving the above object, a method for producing a metal plate having a photocatalyst layer, and a metal plate having a photocatalyst layer produced thereby are proposed.
[0010]
[Means for Solving the Problems]
In the Japanese Patent Application Laid-Open No. 2001-73169 and Japanese Patent Application No. 2001-83417, the inventor applied a phosphate aqueous solution containing no organic solvent such as aluminum phosphate and magnesium phosphate in which TiO 2 particles are dispersed to a metal plate. It has been proposed that by baking at a temperature of 350 ° C. or higher, a surface coating having excellent processability, adhesion and photocatalytic properties can be formed. The present invention further advances these proposals, and further adds an appropriate amount of nitric acid, organic acid, and one or more of these salts to a phosphate aqueous solution containing TiO 2 particles including a TiO 2 precursor. The present invention was completed by discovering that the adhesion and photocatalytic function of the coating can be increased by coating and baking on a metal plate.
[0011]
Photocatalyst layer forming aqueous coating liquid of the present invention, the mass ratio, 100 parts of a total amount of converted to water-soluble phosphate and / or a water-soluble phosphate salt PO 4, TiO 2 particles in terms of TiO 2 And / or one or more TiO 2 precursors in a total amount of 140 to 700 parts, in terms of NO 3 , nitric acid and / or a salt thereof in a total amount of 5 to 50 parts , selected from an organic acid and a salt thereof In addition, one or more kinds are contained in a total amount of 5 to 400 parts .
[0012]
In the aqueous coating liquid for forming the photocatalyst layer , the TiO 2 precursor may be ammonium ammonium oxalate. Further, the water-soluble phosphate is any one selected from aluminum monophosphate, magnesium monophosphate, manganese monophosphate, zinc monophosphate and calcium monophosphate, or a mixture thereof. It is good. The above aqueous coating liquid for forming a photocatalyst layer may further contain 20 to 35 parts of ammonia with respect to 100 parts of the nitrate radical contained therein.
[0013]
The above-mentioned photocatalyst layer forming coating solution is applied to the surface of the metal plate so that the thickness after baking is 0.3 to 9 g / m 2 and then baked at an ambient temperature of 350 to 700 ° C. at least once. Accordingly, a metal plate having a photocatalytic layer can be produced.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The coating liquid for forming a photocatalyst layer of the present invention is a film that is widely applied to a metal plate, dried and baked to form a hard film having good processability and good photocatalytic properties, particularly a phosphate-based film. Therefore, it adjusts as shown below so that it may have a specific composition. The phosphate-based coating referred to here is a refractory-based insoluble coating formed by dehydration and condensation by heating an aqueous solution mainly composed of a first phosphate coated on a metal. It can contain pigment particles and the like, and is different from a coating film for a coating base that is treated on an ordinary iron or zinc surface in an aqueous solution of 80 ° C. or less.
[0015]
First, the phosphate aqueous solution is adjusted. The adjustment is preferably carried out by blending a phosphoric acid aqueous solution with a metal salt such as an oxide, hydroxide or carbonate of a metal such as aluminum, magnesium, manganese, calcium or zinc. The compounding amount of the metal salt with respect to phosphoric acid may be in the range of 1.2 to 0.8 which is a necessary amount for producing the primary phosphate by reaction with phosphoric acid at a molar ratio. When the blending amount is less than 0.8, it takes a long time to form a water-insoluble film, which is not preferable. When it exceeds 1.2, insoluble particles are likely to be generated, and the surface state is deteriorated. The phosphate concentration of the aqueous phosphate solution is 1 to 15%, preferably 3 to 12% in terms of mass ratio in terms of PO 4 .
[0016]
One or more TiO 2 particles and / or TiO 2 precursors are added to the phosphate aqueous solution prepared as described above. These blending amounts are preferably determined by the photocatalytic function of the formed film, the hardness of the formed film, and the like. In general, when using TiO 2 fine particles or sol, the ratio of TiO 2 to PO 4 is relatively small, whereas when using a TiO 2 precursor such as titanyl ammonium oxalate, the ratio is increased. be able to.
[0017]
Specifically, when adding one or more kinds of TiO 2 fine particles or sol, the total amount of water-soluble phosphate and / or water-soluble phosphate converted to PO 4 is 100 parts. The total amount of TiO 2 is 140 to 250 parts, preferably 150 to 200 parts. If the TiO 2 equivalent is less than 140 parts, the photocatalytic performance becomes insufficient, while if it exceeds 250 parts, the hardness of the resulting coating is lowered and wrinkles are not preferred. In particular, the range of 150 to 200 parts is preferable from the viewpoint of photocatalytic performance and coating hardness. The titanium oxide added to the phosphate aqueous solution may be either powder or sol. In particular, a fine powder having a crystallite diameter of 35 nm or less and a specific surface area (BET) of 50 m 2 / g or more or an equivalent sol slurry is preferable.
[0018]
A precursor of TiO 2 can also be used. As the precursor, organic titanium compounds such as titanyl sulfate, titanium chloride, hydrated titanium phosphate compounds, titanyl ammonium oxalate, titanium alkoxides, chelates, and acetate can be used to generate TiO 2 by heating at 250 ° C or higher. It is. Among them, when using an aqueous solution of titanium ammonium oxalate, it is possible to produce more TiO 2 with respect to PO 4 as a binder, so that it is possible to produce a metal plate having a photocatalytic layer that exhibits excellent photocatalytic properties. It becomes possible. For example, the aqueous titanium ammonium oxalate solution can be 200 to 700 parts in terms of TiO 2 with respect to 100 parts in terms of the total amount of water-soluble phosphate and / or water-soluble phosphate converted to PO 4 . These TiO 2 precursors and TiO 2 fine particles or sols can coexist.
[0019]
To the mixed solution, 5 to 50 parts of nitric acid or a salt thereof is added in terms of NO 3 to 100 parts of phosphate (PO 4 equivalent). Thereby, the adhesiveness of the film produced | generated by baking can improve. The effect is recognized from the addition of 5 parts or more per 100 parts of phosphate (PO 4 equivalent), and is almost saturated at 50 parts. The amount is preferably 10 to 30 parts with respect to 100 parts of phosphate (PO 4 equivalent). As a chemical, aluminum nitrate nonahydrate, that is, Al (NO 3 ) 3 .9H 2 O, is commercially available and can be suitably used.
[0020]
In the aqueous coating solution for forming a photocatalyst layer prepared as described above, an organic acid such as oxalic acid and formic acid, and one or more selected from these salts are added in a mass ratio to 100 parts of phosphate (PO 4 equivalent). The total content can be adjusted to 5 to 400 parts, preferably 60 to 270 parts. This adjustment is performed by adding an organic acid to the mixed solution. As a result, the adhesion of the coating to the metal, the wear resistance, and the photocatalytic function can be further increased.
[0021]
When the formic acid is selected as the organic acid, the NO x removal effect is particularly improved. This effect appears when 5 parts or more is added to 100 parts of phosphate (PO 4 equivalent). However, if it exceeds 70 parts, the hardness of the coating will decrease. Therefore, the blending amount of formic acid is preferably 5 to 70 parts. When oxalic acid is selected, an effect is observed in improving the adhesion and wear resistance of the coating. The blending amount is preferably 50 to 300 parts by mass with respect to 100 parts of phosphate (in terms of PO 4 ). This is because the improvement effect is not recognized when the amount is less than 50 parts, and when the amount exceeds 300 parts, the hardness of the coating film decreases. 100-250 parts is preferred. When oxalate or titanyl ammonium oxalate is used as the TiO 2 precursor in the above formulation, oxalic acid contained therein is included in the organic acid salt. The formic acid, oxalic acid, titanyl ammonium oxalate and the like can coexist in the proper blending range.
[0022]
Also, when titanyl ammonium oxalate is used as the TiO 2 precursor, it decomposes during the baking process and generates ammonia, so NO X generated from nitrate radicals in the deodorizer of the continuous color coating line is converted to N 2 and H 2 O. preferred can be prevented the occurrence of the NO X is decomposed into and. Instead of titanyl ammonium oxalate, 20 to 35 parts of ammonia and / or ammonium salt can be blended with 100 parts of nitric acid radical or 100 parts of nitrate radical in the treatment liquid. However, if the pH of the treatment liquid increases due to the mixing of ammonia, the adhesion of the coating film to the base metal decreases, so the amount of ammonia is controlled so that the pH of the treatment liquid is maintained at 3.5 or lower, preferably 2.0 or lower. Should.
[0023]
The photocatalyst layer-forming coating liquid of the present invention has the above composition, and a color pigment can be added thereto to improve the design of a metal plate having a photocatalyst layer as a product. In addition, an appropriate amount of a lubricant such as wax can be added to improve the roll formability of the product. In addition, a thickening material that increases the viscosity of the treatment liquid so that it can be easily applied by a roll coater can be added within a range that does not impair the object of the present invention.
[0024]
The photocatalyst layer forming coating solution is applied to the surface of a metal plate such as a steel plate or an aluminum plate, and is used for manufacturing a metal plate having a photocatalyst layer. Any metal plate may be used, but an aluminum plate, an aluminum-zinc alloy plated steel plate such as 55% aluminum-zinc alloy plated steel plate, a galvanized steel plate, or a stainless steel plate may be used. All of these have a high degree of corrosion resistance, and can be a highly corrosion-resistant building material used outdoors. In addition, in the case of indoor use, those with slightly inferior weather resistance such as chrome-plated tin-free steel and general cold-rolled steel sheets can be used. There are no particular restrictions on the means for coating and baking. For example, a known color steel plate or color aluminum plate production line can be used, and equipment for continuous coating baking of 2 coats and 2 bakes with a line speed of 10 to 150 m / min can be suitably used.
[0025]
The amount of coating formed is preferably in the range of 1 to 15 g / m 2 by dry weight. When the adhesion amount is 1 g / m 2 or less, it is difficult to obtain a photocatalytic function other than super hydrophilicity, and when it exceeds 15 g / m 2 , only a soft film that is powdery or wrinkled is obtained and bending workability is low. Because it becomes.
[0026]
In the formation of the above-mentioned film, a 2-coat-2bake method is employed in which the coating amount per application is 0.3 to 9 g / m 2 in the thickness after baking, and then the baking process is performed twice or more. It is good to do. This is because when the coating amount per one time exceeds 9 g / m 2 , only a soft film that is easily powdery or wrinkled is obtained and bending workability is also lowered. In this case, the treatment liquids of the first layer and the second layer need not be the same as long as the composition is within the scope of the present invention. A film having a sufficient thickness capable of exhibiting photocatalytic properties can be formed by the 2-coat-2bake method.
[0027]
The baking temperature may be the baking temperature used for forming the phosphoric acid-based film. For example, the coating liquid was applied in an atmosphere of 350 ° C or higher so that the surface photocatalyst layer reached 250 ° C or higher using a hot air oven. The surface should be heated. It should be noted that when the baking atmosphere temperature is 350 ° C. or lower, the phosphate coating film is hygroscopic in the air, and when the baking temperature is 700 ° C. or higher, the zinc-based plating layer is dissolved and the aluminum plate is softened. In the equipment for continuous coating baking of 2 coats and 2 bake, the first coating baking furnace for undercoating is generally applied in the atmosphere where the second layer is applied and baking is performed at 350 ° C or higher even when the temperature is low and the temperature cannot be raised to 350 ° C or higher. When baked on, a film with no hygroscopicity and excellent photocatalytic function can be obtained.
[0028]
[Example 1]
Anatase-type TiO 2 powder with a crystallite diameter of 6 nm in mass ratio {Taika TKP-101}: 10 g, magnesium phosphate: 5 g, aluminum nitrate 9 hydrate: 2.5 g, oxalic acid dihydrate: 12 g, formic acid: An aqueous processing solution composed of 2 g and water ion-exchanged water: 60 g was prepared as a photocatalyst layer-forming coating solution. This was coated on a 0.35mm thick 55% aluminum-zinc alloy plated plate AZ150 with a bar coater and baked in an atmospheric furnace maintained at 400 ° C for 70s, once baked at a dry film thickness of 1.9g / m 2 Got. After this one-time baking plate was cooled, the above treatment liquid was further applied and baked on the same conditions as the previous time to obtain a coated plate with a total dry film thickness of 3.5 g / m 2 . Even if the obtained coated plate was bent 180 ° into a round bar having a diameter of 5 mm, the inside did not peel off at all, and the adhesion of the film was good.
[0029]
[Example 2]
100 g of titanyl ammonium oxalate aqueous solution (5 g of TiO 2 equivalent), 20 g of anatase-type TiO 2 powder with a crystallite size of 15 nm (Taika TKP102), 5 g of primary aluminum phosphate, 1.5 g of aluminum nitrate 9 hydrate, formic acid An aqueous treatment solution containing 1.6 g was prepared as a photocatalyst layer-forming coating solution. This was applied to an A5052 aluminum plate with a thickness of 1.0 mm and baked in an atmospheric furnace maintained at 350 ° C. for 70 s to form a coating film with a dry film thickness of 2.1 g / m 2. And baked at 450 ° C. for 70 seconds to obtain a coated plate having a total dry film thickness of 6.7 g / m 2 . The obtained coated plate showed good film adhesion because the inner side did not peel at all even if it was bent 180 ° into a round bar having a diameter of 5 mm.
[0030]
The photocatalytic properties of the coated metal plates obtained in Examples 1 and 2 were measured. The water contact angle for the painted metal plate of Example 1 was 1.8 °, and the water contact angle for the painted metal plate of Example 2 was 0 °. After putting the coated metal plate sample was adjusted to the surface area 49cm 2 glass container 0.5 liter, acetaldehyde concentration 100ppm of air was injected, each immediately 10min min UV intensity is irradiated with light of the black light 1 mw / cm 2 Was used as an index of deodorizing performance. In the case of Example 1, the deodorization performance reached 3.8 ppm after 30 minutes and 0.3 ppm after 60 minutes, and in Example 2, it reached 0 ppm after 20 minutes.
[0031]
In addition, the de-NO X performance Resources and Environment Institute of Technology was measured in accordance with TR draft that was created. In other words, put a 5 cm wide and 10 cm long test piece in a container so that the black light is irradiated at an illuminance of 10 W / m 2 or less at a position 5 mm below the quartz window, and a NO gas of 1.0 ppm with a dew point of 25 ° C. It was introduced for 5 hours at a flow rate of 3 l / min (12 m / min). The tested samples were immersed in purified water and the nitrate and nitrite ion concentrations were measured to calculate the NO x elution amount. As a result, in the case of Example 1, the elution amount was 14.3 μmol, and in the case of Example 2, 18.5 μmol.
[0032]
As is clear from the above examples, the metal member having photocatalytic activity of the present invention is super hydrophilic when used for various members used outdoors, such as exterior materials such as soundproof walls of highways and siding of buildings. and always a clean by decomposition of pollutants can help remove of the NO X required without the air cleaning.
[0033]
For example, if it is used for indoor walls or blind slats, it can effectively remove malodor and formaldehyde generated from the adhesive of interior building materials, which is the cause of so-called sick house. Furthermore, it is also effective for preventing adhesion due to tobacco smoke, preventing mold, and antibacterial. Furthermore, since the metal member having photocatalytic activity of the present invention is manufactured by baking at a high temperature, there is no generation of a solvent or the like when used indoors.
[0034]
【The invention's effect】
The present invention has a structure in which a phosphate-based baking film is formed on a metal plate, and anatase-type titanium dioxide fine particles are supported through the coating film, so that the adhesion and workability to the metal plate are good and the photocatalytic property is high. It is possible to produce a pre-coated metal plate that is effective and can be exhibited for a long time. And the metal member manufactured using it has the outstanding photoactive catalyst function, and can be used for purification | cleaning of living environment using it for various indoor and outdoor structures. Also, when a high-strength aluminum plate such as 5182 or 5052 is used as the substrate, the annealing temperature of the coating film matches the annealing temperature, so the annealing process can be omitted by applying this treatment liquid and baking after degreasing. .
Claims (5)
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| JP3817603B2 (en) * | 2003-10-30 | 2006-09-06 | 敏夫 入江 | Photocatalyst particle fixing coating agent and photocatalyst particle fixing method |
| JP4907315B2 (en) * | 2006-11-28 | 2012-03-28 | 新日本製鐵株式会社 | Surface-treated metal material |
| JP4817326B2 (en) * | 2007-05-30 | 2011-11-16 | 国立大学法人 千葉大学 | Amorphous phosphoric acid-titanium oxide oxidation catalyst |
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