JP3808409B2 - Method for producing metal material with excellent photocatalytic activity - Google Patents
Method for producing metal material with excellent photocatalytic activity Download PDFInfo
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- JP3808409B2 JP3808409B2 JP2002205358A JP2002205358A JP3808409B2 JP 3808409 B2 JP3808409 B2 JP 3808409B2 JP 2002205358 A JP2002205358 A JP 2002205358A JP 2002205358 A JP2002205358 A JP 2002205358A JP 3808409 B2 JP3808409 B2 JP 3808409B2
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- titanium oxide
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- 239000007769 metal material Substances 0.000 title claims description 31
- 230000001699 photocatalysis Effects 0.000 title claims description 30
- 238000004519 manufacturing process Methods 0.000 title claims description 7
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 53
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 50
- 239000010445 mica Substances 0.000 claims description 30
- 229910052618 mica group Inorganic materials 0.000 claims description 30
- 238000005422 blasting Methods 0.000 claims description 19
- 239000000843 powder Substances 0.000 claims description 14
- RJDOZRNNYVAULJ-UHFFFAOYSA-L [O--].[O--].[O--].[O--].[O--].[O--].[O--].[O--].[O--].[O--].[F-].[F-].[Mg++].[Mg++].[Mg++].[Al+3].[Si+4].[Si+4].[Si+4].[K+] Chemical compound [O--].[O--].[O--].[O--].[O--].[O--].[O--].[O--].[O--].[O--].[F-].[F-].[Mg++].[Mg++].[Mg++].[Al+3].[Si+4].[Si+4].[Si+4].[K+] RJDOZRNNYVAULJ-UHFFFAOYSA-L 0.000 claims description 13
- 239000010419 fine particle Substances 0.000 claims description 13
- 239000011521 glass Substances 0.000 claims description 10
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- 238000002156 mixing Methods 0.000 claims description 6
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- 239000010408 film Substances 0.000 description 25
- 238000000034 method Methods 0.000 description 14
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- 239000011248 coating agent Substances 0.000 description 8
- 238000000576 coating method Methods 0.000 description 8
- 239000011230 binding agent Substances 0.000 description 7
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- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 4
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 4
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
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- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 1
- LCKIEQZJEYYRIY-UHFFFAOYSA-N Titanium ion Chemical compound [Ti+4] LCKIEQZJEYYRIY-UHFFFAOYSA-N 0.000 description 1
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Description
【０００１】
【産業上の利用分野】
本発明は、長期にわたって光触媒活性を維持し、抗菌性，耐汚染性および耐指紋性に優れた金属材料の製造方法に関する。
【０００２】
【従来の技術】
アナターゼ型の酸化チタンに、そのバンドギャップ以上のエネルギ−を有する波長の光を照射した場合、光励起により伝導帯に電子が、価電子帯に正孔が生じ、生じた正孔は強い酸化力を有するので、酸化チタン表面に接触した有機物はその酸化還元作用によって分解される。このような光触媒作用を利用して、酸化チタンを、防汚，抗菌，脱臭，ＮＯｘ・ＳＯｘ分解等、種々の環境対策に応用しようとしている。すなわち、酸化チタンを含む皮膜をガラス，プラスチックス，金属等の基体表面に形成し、防汚，抗菌，脱臭，ＮＯｘ・ＳＯｘ分解等に活用しようとするものである。
優れた光触媒活性を発揮させるためには、酸化チタンは表面積を大きくした状態で使用されることが好ましい。このため、一般的にはバインダ成分中に微細粉末形状で分散され、バインダ成分とともに基体表面に薄膜状に被覆して光触媒層を形成して使用されている。そして、光触媒作用を十分に発揮し、しかも光触媒層自身の密着性や耐久性を高めるために、バインダ成分の選択を含め、光触媒層の形成方法に関して各種検討が進められている。
【０００３】
【発明が解決しようとする課題】
基体表面に光触媒層を形成するには、酸化チタン微粒子を含む樹脂塗料組成物を浸漬やスプレー等の方法で塗装し、焼付け乾燥して成膜する方法が最も簡便である。しかしながら、樹脂塗膜は硬さや加工性が十分でなく、塗装金属材料の加工時にクラックが発生したり、疵が付きやすい他、接着力も低いため塗膜が剥がれやすい。さらに、光触媒層の酸化還元作用により塗膜樹脂自体が化学変化して、塗膜が変色，劣化するという問題もある。
そこで、有機物に代わって無機物質をバインダ成分に使用しようとする検討も行われている。
【０００４】
基板表面に酸化チタンをＣＶＤ法で蒸着させたり、プラズマ溶射を行う方法が特開平６−２１０１７０号公報で提案されているが、いずれの方法も製造コストが非常に高くなる。
また、特開平９−３０１７４２号公報では、光触媒機能と耐指紋性機能を得ることを目的として、チタンを含む金属酸化物ゾルが鎖状でコロイダルシリカを含む複合溶液を塗布し、焼成することにより、皮膜を形成する方法が、さらに特開平２−５０１５４号公報では、多孔性ガラスにチタン（IV）テトラブトキシオキサイドのアルコール溶液を含浸し、加熱してアナターゼ型の酸化チタンを固定する方法が提案されている。しかしながら、これらの方法でも塗布する溶液の粘度や塗布条件によって形成される皮膜に厚みが変化し易いばかりでなく、基板から剥離し易い等の問題がある。さらにまた、特開平１０−１８０８２号公報では、金属材料を陽極体としてチタン酸およびペルオキソチタン酸等のコロイド溶液を通電し、チタン化合物含有皮膜を形成し、この皮膜を乾燥、焼成することにより酸化チタンの皮膜を形成する方法が提案されている。しかし、これらの方法による皮膜は粉末状での形態ではなく、バルク状態であるため、粉末のまま酸化チタンを固定したものよりも表面積が小さくなり、光触媒機能は相対的に低い。
【０００５】
特開平１０−１９８２７４号公報には、ステンレス鋼板上に設けた釉薬層中に酸化チタン微粒子を固着することにより、汚染防止を図ったステンレス表示板が記載されている。この技術においても、光触媒機能を期待する酸化チタン微粒子は緻密なガラス釉薬層で完全に被覆されて固定化されているので、水あるいは大気は釉薬層中の酸化チタン表面に達せず、含有している酸化チタンの光触媒機能を十分に発揮できていない。
【０００６】
ところで、金属材料を環境衛生上問題になるトイレ，洗面所あるいは食品衛生工場の天井，壁，床等のパネルなどに適用しようとすると、抗菌性，耐汚染性，脱臭性，有機物分解性，親水性，防汚性，耐指紋性等を有する光触媒機能をもつことが要求される。
上記した皮膜の形成方法では、バルク状態の皮膜が形成されるか、酸化チタン微粒子が緻密なバインダー層，釉薬層で被覆されて固定化されているために、最表面に露出した酸化チタンのみしか光触媒機能を発現できていない。固定化している膜状物質が酸化チタンの表面反応を阻害しているためである。
脱臭性，有機物分解機能は、極めて高い光触媒機能を必要とし、できるだけ高い表面積を得ることを必要としているので、酸化チタン微粒子を粉体の状態で、しかも表面を露出した状態で存在させることが望まれる。
【０００７】
本発明は、このような問題を解消すべく案出されたものであり、金属材料表面に、露出表面積を広くした態様で酸化チタン微粒子を含有する無機系皮膜を形成して、光触媒機能の他に各種機能を発現できる金属材料を提供することを目的とする。
【０００８】
【課題を解決するための手段】
本発明の光触媒活性に優れた金属材料の製造方法は、その目的を達成するため、０．５質量％以上の酸化チタン微粉末を合成雲母に添加混合した混合粉末を投射材として金属材料表面にブラスト処理を施し、金属材料表面に酸化チタン微粒子が分散された雲母層を付着形成することを特徴とする。
使用する酸化チタン粉末としては平均粒径１．０μｍ以下のものを、合成雲母としては長径が２０〜３０μｍのものを使用することが好ましい。
雲母層を形成した後、さらにガラスビーズを用いたブラスト処理を施して、前記雲母層を緻密化することが好ましい。
【０００９】
【作用】
本発明者等は、光触媒機能を有する酸化チタン微粉末を、金属材料表面に無機質材料で固定するために、バインダ成分になる無機材料とその皮膜形成手段について、種々検討を続けてきた。
その結果、合成雲母をブラスト法で吹き付けると、雲母は砕かれ、金属材料表面で互いの衝突エネルギーで半溶融状態となって強固に金属材料表面に固着されることが確認された。
この際、予め合成雲母中に微細な酸化チタン粉末が十分に攪拌・混合されていると、電気絶縁性の高い雲母の静電引力により表面に酸化チタンが付着された雲母が得られる。そして、この混合粉を投射材としてブラストすると、酸化チタン微粉末は雲母表面に付着されたまま金属材料表面に投射され、金属材料表面に付着された雲母中に抱き込まれた状態で保持され、金属材料表面に固定されることになる。
【００１０】
表面の皮膜構造を図１に基づいて説明する。
全体に微細なポーラス態様を示している。雲母は硬度が低い（モース硬度：３．４）ために、ブラスト処理により容易に燐片形状がくずれ、その状態で堆積されてポーラスな形態を示している。ブラスト時、雲母に付着していた酸化チタン微粒子はそのまま内部に取り込まれた状態になっている。このため、表面水および大気がポーラスな構造の内部にも入り込め酸化チタン表面に容易に到達できるので、内部に存在する酸化チタンも光触媒機能を発現できている。すなわち、バルク状態あるいは緻密な結合層による固着状態よりも実質的な表面積が大きくなっているために、優れた光触媒機能を発現できている。さらに、最表面も凹凸形状を有しており、表面積の増大に寄与している。
【００１１】
酸化チタン微粒子が、金属材料表面にポーラスな雲母層に取り込まれた形態で固定されているために、十分な光触媒機能が発揮できていると推測される。また、光触媒機能をもつ酸化チタン微粒子が無機質の合成雲母成分で固着された形態となっているので、極めて良好な親水性を有している。
本発明により形成された皮膜は、金属材料表面に合成雲母がブラストによる衝突エネルギーで半溶融状態となって強固に固着しているため、塗膜等のバインダ成分を利用した場合に比べ、密着性，曲げ性が高い傾向にある。また、光の乱反射が抑制される微細凹凸を有する無機質皮膜表面であるため指紋が目立ち難く、光触媒機能も高いため付着した指紋も速やかに分解されて消失しやすい。すなわち、耐指紋性も高い。さらに、光触媒活性が高いことに付随して防汚性も高くなると考えられる。
【００１２】
なお、単にブラストして合成雲母を主体とした皮膜を形成しても、当該皮膜は、ポーラスであるために、耐候性（耐水性）の点で十分ではない。そのため、耐水性等が要求される部材へ適用する場合には、合成雲母を主体とした皮膜を形成した後、ガラスビーズ等を用いてブラスト処理すると、皮膜の密度が高められ、粗い表面の凹凸も緻密・微細な凹凸に変化するため、耐候性，密着強度も向上する。
【００１３】
【実施の態様】
本発明の酸化チタン微粒子分散雲母層を被着させる金属材料は、特に制限されない。冷延炭素鋼板，ステンレス鋼板，アルミニウム合金板等が使用できる。
ブラスト処理により酸化チタン微粒子分散雲母層を被着させる金属材料には、基本的には特別な前処理を施す必要はないが、表面に疵，汚れあるいはスケール等が存在している場合には、アルミナ等の硬質な研掃材を用いて除去しておくことが好ましい。
【００１４】
投射材の主たる成分である雲母の種類には、特に制限はない。用途に応じた意匠性を考慮して所望の色調の雲母を選択しても良い。また、雲母の粒径も酸化チタンが雲母とともにブラスト処理可能で、成膜が形成できるだけの運動エネルギーをもつことができる粒径であれば十分である。
使用する酸化チタンとしては、ルチル型，アナターゼ型のいずれのものも使用可能であるが、優れた光触媒機能を得るためにはアナターゼ型の酸化チタンを使用することが好ましい。光触媒活性を高めるためには、より細かい粒径の酸化チタンを使用することが好ましい。１．０μｍ以下のものを使用することが望ましい。
また、投射材における配合割合については、雲母と酸化チタンの体積比でほぼ５：１が混合下限界であり、その割合から０．５質量％以上の混合が可能である。雲母層に効率的に固定され、優れた光触媒機能を発揮させるためには、１〜３０質量％の割合で雲母と混合しておくことが好ましい。
【００１５】
ブラスト処理後の皮膜中成分の均一化を図るためには、この投射材の雲母と酸化チタンを均一に混合しておく必要がある。雲母を粉砕しないように、かつ雲母に静電気を発生させて酸化チタン微粒子を付着させる必要がある。このためには、合成樹脂製の容器に各粉体を投入し、アルミナやジルコニア等のボールを同時に投入して容器自体を回転させて混合する形式を採ることが好ましい。
ブラスト処理に使用する装置としては、空気式加速装置，機械式加速装置等のいずれの方式のものも使用可能である。処理膜の密着性や投射効率を考慮すると、より高い投射速度が得られる直圧式の空気式加速装置を用いることが好ましい。
【００１６】
合成雲母を主体とした皮膜を形成した後、皮膜を緻密化するためにガラスビーズ等でブラスト処理する際、使用するブラスト材としては一般的な材質のソーダガラスで十分である。またその形状も球状のものを使用することが好ましい。表面の緻密化との関係においては、粒径が０．１ｍｍ程度のものを使用することが好ましい。
また、投射圧力は、研削作用が発現しない範囲の０．１ＭＰａ程度を実施することが好ましい。
【００１７】
【実施例】
実施例１ :
長径３０μｍの合成雲母（トピー工業社製、ＰＤＭ−７−８０）９０質量％と粒径０．０５μｍ以下の酸化チタン粉末（日本エアロジル社製、Ｐ２５）１０質量％を秤量し、自作の混合装置に、粉体体積に対して約３０％を占めるように直径１０ｍｍのジルコニアボールを適正数入れ、５分程度混合攪拌して投射材を調製した。
被投射材としてＳＵＳ３０４鋼板のＢＡ仕上げ材を用い、直径１０ｍｍの噴射ノズルを有する直圧式ブラスト装置を使用して０．３ＭＰａの空気圧で約５分程度ブラスト処理して、表面に付着層を有するステンレス鋼板を得た。
ブラスト処理後、処理面をＥＰＭＡで元素分析して、表面にＳｉ，ＡｌおよびＯの他にＴｉが存在することを確認した。
この被覆金属材料について各種特性を調査した。
なお比較材として、同じステンレス鋼板のＢＡ材を用いた。
各特性の評価手法、評価基準は表１に示す通りである。
表１中、「ＣＣＴ」と表記した塩乾湿複合サイクル試験は、塩水噴霧（５％ＮａＣｌ，１０分）→乾燥（６０℃，３０％ＲＨ，６０分）→湿潤（５０℃，９５％ＲＨ，１８０分）を１サイクルとするものである。
【００１８】
実施例２
実施例１で使用した合成雲母，酸化チタン粉末，混合条件，ステンレス鋼板，ブラスト条件を用い、酸化チタン粉末の混合割合のみを、０，０．５，１，５，１０，２０，２５，３０，４０，５０，９９質量％に変えて、合成雲母層を形成した。
そして、実施例１と同じ手法で各種特性について調査した。
その結果を表２に示す。
【００２１】
実施例３：
実施例１により製造した酸化チタン分散雲母層を形成した鋼板に、さらに、平均粒径１００μｍの球形ガラスビーズを噴射圧力０．１ＭＰａでブラスト処理した。この条件は、研削作用を抑え、押し付け力を付与することが可能な範囲で設定したものである。
後処理した処理鋼板の特性を、実施例１と同じ手法で調査した。
その結果を表４に示す。
この表に示す４項目の特性は、ガラスビーズブラスト処理することにより、大きく向上していた。その他の特性については、ガラスビーズブラスト処理の施していないものとほぼ同等の特性を示し、特性の低下は認められなかった。
【００２３】
【発明の効果】
以上に説明したように、光触媒活性に優れた酸化チタン微粒子を雲母とともに金属材料表面にブラスト処理すると、金属材料表面に酸化チタン微粒子が分散されたポーラスな雲母層が形成されるため、大気や水と接触する酸化チタン微粒子の表面積を大きくして光触媒機能を最大限利用することができる。
また、酸化チタンを固定している雲母層はブラスト処理により金属材料に半溶融状態で固着されているので付着強度が高いため、密着強度が高く、加工性にも優れている。しかも層形成手段に由来した微細凹凸を有しているため、親水性や耐指紋性を有する等、本来の光触媒機能とそれに付随した多機能を有しているので、光触媒機能付加金属材料の用途を大幅に拡大することが可能になる。
【図面の簡単な説明】
【図１】 酸化チタン分散雲母層を形成した金属材料表面の断面構造を模式的に説明する図[0001]
[Industrial application fields]
The present invention maintains the photocatalytic activity for a long time, antimicrobial, a method of manufacturing a metal material having excellent stain resistance and fingerprint resistance.
[0002]
[Prior art]
When anatase-type titanium oxide is irradiated with light having a wavelength greater than its band gap, electrons are generated in the conduction band and holes in the valence band by photoexcitation, and the generated holes have strong oxidizing power. Therefore, the organic matter that contacts the titanium oxide surface is decomposed by its redox action. Using such a photocatalytic action, titanium oxide is being applied to various environmental measures such as antifouling, antibacterial, deodorizing, NOx / SOx decomposition, and the like. That is, a film containing titanium oxide is formed on the surface of a substrate such as glass, plastics, or metal, and is intended to be used for antifouling, antibacterial, deodorization, NOx / SOx decomposition, and the like.
In order to exhibit excellent photocatalytic activity, it is preferable to use titanium oxide with a large surface area. For this reason, it is generally used in the form of a fine powder dispersed in a binder component and coated on the surface of the substrate together with the binder component in a thin film to form a photocatalytic layer. And in order to fully exhibit the photocatalytic action, and to improve the adhesion and durability of the photocatalyst layer itself, various studies have been made on the method of forming the photocatalyst layer, including the selection of the binder component.
[0003]
[Problems to be solved by the invention]
The simplest method for forming a photocatalyst layer on the substrate surface is to form a film by applying a resin coating composition containing fine titanium oxide particles by dipping or spraying, baking and drying. However, the resin coating film is insufficient in hardness and workability, cracks are easily generated during processing of the coated metal material, and the coating film is easily peeled off due to the tendency to have wrinkles and low adhesion. Furthermore, the coating resin itself undergoes a chemical change due to the redox action of the photocatalyst layer, causing a problem that the coating is discolored and deteriorated.
Therefore, studies are underway to use inorganic substances as binder components instead of organic substances.
[0004]
Japanese Patent Laid-Open No. 6-210170 proposes a method of depositing titanium oxide on the surface of a substrate by a CVD method or performing plasma spraying, but both methods are very expensive to manufacture.
In JP-A-9-301742, for the purpose of obtaining a photocatalytic function and an anti-fingerprint function, a composite solution containing colloidal silica in which a metal oxide sol containing titanium is chained is applied and fired. In addition, JP-A-2-50154 proposes a method for impregnating porous glass with an alcohol solution of titanium (IV) tetrabutoxy oxide and fixing the anatase-type titanium oxide by heating. Has been. However, even with these methods, there is a problem that not only the thickness is easily changed depending on the viscosity of the solution to be applied and the coating conditions, but also the film is easily peeled off from the substrate. Furthermore, in Japanese Patent Application Laid-Open No. 10-18082, a metallic material is used as an anode body and a colloidal solution such as titanic acid or peroxotitanic acid is energized to form a titanium compound-containing film, and this film is dried and fired to oxidize. A method of forming a titanium film has been proposed. However, since the film formed by these methods is not in the form of powder but is in a bulk state, the surface area is smaller than that in which titanium oxide is fixed as it is, and the photocatalytic function is relatively low.
[0005]
Japanese Patent Application Laid-Open No. 10-198274 describes a stainless steel display plate that prevents contamination by fixing titanium oxide fine particles in a glaze layer provided on a stainless steel plate. Also in this technology, since the titanium oxide fine particles that are expected to have a photocatalytic function are completely covered and fixed with a dense glass glaze layer, water or the air does not reach the titanium oxide surface in the glaze layer and is contained. The photocatalytic function of titanium oxide is not fully demonstrated.
[0006]
By the way, when trying to apply metal materials to toilets, washrooms or food sanitation factories, which are environmentally sanitation problems, such as ceilings, walls, floors, etc., antibacterial properties, stain resistance, deodorization, organic matter decomposability, hydrophilicity Photocatalytic functions such as anti-fouling property, antifouling property and fingerprint resistance are required.
In the above-described film formation method, a bulk film is formed, or titanium oxide fine particles are coated and fixed with a dense binder layer and glaze layer, so that only the titanium oxide exposed on the outermost surface is fixed. The photocatalytic function cannot be expressed. This is because the immobilized film-like substance inhibits the surface reaction of titanium oxide.
The deodorization and organic matter decomposition functions require extremely high photocatalytic functions, and it is necessary to obtain as high a surface area as possible. Therefore, it is desirable that fine particles of titanium oxide exist in a powdery state with the surface exposed. It is.
[0007]
The present invention has been devised to solve such problems, and an inorganic coating film containing fine titanium oxide particles is formed on the surface of a metal material in a mode in which the exposed surface area is widened. Another object is to provide a metal material that can exhibit various functions.
[0008]
[Means for Solving the Problems]
In order to achieve the object of the method for producing a metal material excellent in photocatalytic activity of the present invention, a mixed powder in which 0.5% by mass or more of titanium oxide fine powder is added to and mixed with synthetic mica is used as a projection material on the surface of the metal material. Blasting is performed to form a mica layer in which titanium oxide fine particles are dispersed on the surface of the metal material.
It is preferable to use a titanium oxide powder having an average particle size of 1.0 μm or less and a synthetic mica having a major axis of 20 to 30 μm.
After forming the mica layer, it is preferable that the mica layer is further densified by further blasting using glass beads .
[0009]
[Action]
In order to fix the titanium oxide fine powder having a photocatalytic function to the surface of the metal material with an inorganic material, the present inventors have continued various studies on an inorganic material that becomes a binder component and a film forming means thereof.
As a result, it was confirmed that when the synthetic mica was sprayed by the blast method, the mica was crushed and became a semi-molten state by the collision energy on the metal material surface and firmly fixed to the metal material surface.
At this time, if fine titanium oxide powder is sufficiently stirred and mixed in the synthetic mica in advance, mica having titanium oxide attached to the surface by electrostatic attraction of mica having high electrical insulation can be obtained. And when this mixed powder is blasted as a projection material, the titanium oxide fine powder is projected onto the metal material surface while adhering to the mica surface, and held in a state of being held in the mica adhering to the metal material surface, It will be fixed to the surface of the metal material.
[0010]
The surface film structure will be described with reference to FIG.
A fine porous aspect is shown as a whole. Since mica has a low hardness (Mohs' hardness: 3.4), the shape of the flakes is easily broken by blasting, and is deposited in this state to show a porous form. At the time of blasting, the fine titanium oxide particles adhering to the mica are taken into the inside as they are. For this reason, since surface water and the atmosphere can enter the porous structure and easily reach the surface of the titanium oxide, the titanium oxide existing inside can also exhibit the photocatalytic function. That is, since the substantial surface area is larger than that in a bulk state or a fixed state by a dense bonding layer, an excellent photocatalytic function can be exhibited. Furthermore, the outermost surface also has an uneven shape, contributing to an increase in surface area.
[0011]
Since the titanium oxide fine particles are fixed on the surface of the metal material in a form taken into the porous mica layer, it is presumed that a sufficient photocatalytic function can be exhibited. Further, since the titanium oxide fine particles having a photocatalytic function are fixed with an inorganic synthetic mica component, they have extremely good hydrophilicity.
The film formed according to the present invention is firmly adhered to the surface of the metal material because the synthetic mica is firmly fixed in a semi-molten state due to the collision energy by blasting, compared to the case where a binder component such as a coating film is used. , Bendability tends to be high. In addition, since the surface of the inorganic coating has fine irregularities that suppress irregular reflection of light, the fingerprint is not conspicuous and the photocatalyst function is high, so that the attached fingerprint is easily decomposed and easily lost. That is, fingerprint resistance is also high. Further, it is considered that the antifouling property is increased with the high photocatalytic activity.
[0012]
Note that even if a film mainly composed of synthetic mica is formed by blasting, the film is porous, and thus is not sufficient in terms of weather resistance (water resistance). Therefore, when applied to members that require water resistance, etc., after forming a film mainly composed of synthetic mica, blasting using glass beads or the like can increase the density of the film, resulting in rough surface irregularities. Changes to dense and fine irregularities, improving weather resistance and adhesion strength.
[0013]
Embodiment
The metal material for depositing the titanium oxide fine particle-dispersed mica layer of the present invention is not particularly limited. Cold rolled carbon steel plate, stainless steel plate, aluminum alloy plate, etc. can be used.
The metal material to which the titanium oxide fine particle-dispersed mica layer is deposited by blasting basically does not need to be pretreated, but if there are wrinkles, dirt or scales on the surface, It is preferable to remove using a hard abrasive such as alumina.
[0014]
There is no restriction | limiting in particular in the kind of mica which is a main component of a projection material. A mica having a desired color tone may be selected in consideration of design properties according to the application. The particle size of mica is sufficient if titanium oxide can be blasted together with mica and can have a kinetic energy sufficient to form a film.
As the titanium oxide to be used, either a rutile type or an anatase type can be used, but in order to obtain an excellent photocatalytic function, it is preferable to use anatase type titanium oxide. In order to increase the photocatalytic activity, it is preferable to use titanium oxide having a finer particle size. It is desirable to use one having a thickness of 1.0 μm or less.
Moreover, about the mixture ratio in a projection material, about 5: 1 is a mixing lower limit by the volume ratio of a mica and a titanium oxide, and 0.5 mass% or more mixing is possible from the ratio. In order to be efficiently fixed to the mica layer and exhibit an excellent photocatalytic function, it is preferably mixed with mica at a ratio of 1 to 30% by mass.
[0015]
In order to make the components in the film after blasting uniform, it is necessary to uniformly mix the mica and titanium oxide of the projection material. It is necessary to attach titanium oxide fine particles so that the mica is not crushed and static electricity is generated in the mica. For this purpose, it is preferable to take a form in which each powder is put into a container made of a synthetic resin, balls such as alumina and zirconia are put together and the container itself is rotated and mixed.
As an apparatus used for the blasting process, any system such as a pneumatic accelerator or a mechanical accelerator can be used. In consideration of the adhesion of the treatment film and the projection efficiency, it is preferable to use a direct pressure pneumatic accelerator capable of obtaining a higher projection speed.
[0016]
When a film mainly composed of synthetic mica is formed and then blasted with glass beads or the like in order to densify the film, a general soda glass is sufficient as a blasting material to be used. In addition, it is preferable to use a spherical shape. In relation to the densification of the surface, it is preferable to use one having a particle size of about 0.1 mm.
Moreover, it is preferable to implement about 0.1 MPa of the range which does not express a grinding effect | action for a projection pressure.
[0017]
【Example】
Example 1 :
Synthetic mica having a major axis of 30 μm (manufactured by Topy Industries, PDM-7-80) and 90% by mass of titanium oxide powder having a particle diameter of 0.05 μm or less (manufactured by Nippon Aerosil Co., Ltd., P25) are weighed, and a self-made mixing device. Then, an appropriate number of zirconia balls having a diameter of 10 mm so as to occupy about 30% of the powder volume was mixed and stirred for about 5 minutes to prepare a projection material.
Stainless steel with an adhesion layer on the surface using a BA finish material of SUS304 steel plate as the projection material and blasting at a pressure of 0.3 MPa for about 5 minutes using a direct pressure blasting device having an injection nozzle with a diameter of 10 mm. A steel plate was obtained.
After the blast treatment, the treated surface was subjected to elemental analysis with EPMA, and it was confirmed that Ti was present in addition to Si, Al and O on the surface.
Various characteristics of this coated metal material were investigated.
As a comparative material, the same stainless steel BA material was used.
Table 1 shows the evaluation method and evaluation criteria for each characteristic.
In Table 1, the combined salt and wet cycle test expressed as “CCT” is salt spray (5% NaCl, 10 minutes) → dry (60 ° C., 30% RH, 60 minutes) → wet (50 ° C., 95% RH, 180 minutes) is one cycle.
[0018]
Example 2
Using the synthetic mica, titanium oxide powder, mixing conditions, stainless steel plate and blasting conditions used in Example 1, only the mixing ratio of titanium oxide powder was 0, 0.5, 1, 5, 10, 20, 25, 30. , 40, 50, and 99% by mass to form a synthetic mica layer.
And various characteristics were investigated by the same method as Example 1.
The results are shown in Table 2.
[0021]
Example 3:
The steel plate formed with the titanium oxide-dispersed mica layer produced in Example 1 was further blasted with spherical glass beads having an average particle size of 100 μm at an injection pressure of 0.1 MPa. This condition is set within a range in which the grinding action is suppressed and the pressing force can be applied.
The characteristics of the post-treated steel sheet were investigated by the same method as in Example 1.
The results are shown in Table 4.
The characteristics of the four items shown in this table were greatly improved by the glass bead blasting process. The other properties were almost the same as those not subjected to glass bead blasting, and no deterioration in the properties was observed.
[0023]
【The invention's effect】
As described above, when the titanium oxide fine particles having excellent photocatalytic activity are blasted together with mica on the metal material surface, a porous mica layer in which the titanium oxide fine particles are dispersed is formed on the metal material surface. The photocatalytic function can be utilized to the maximum by increasing the surface area of the titanium oxide fine particles contacting with the surface.
Moreover, since the mica layer to which titanium oxide is fixed is fixed to the metal material in a semi-molten state by blasting, the adhesion strength is high, so that the adhesion strength is high and the workability is also excellent. In addition, because it has fine irregularities derived from the layer forming means, it has hydrophilicity and fingerprint resistance, etc., so it has the original photocatalytic function and its accompanying multiple functions, so the application of photocatalytic function-added metal materials Can be greatly expanded.
[Brief description of the drawings]
FIG. 1 is a diagram schematically illustrating a cross-sectional structure of a metal material surface on which a titanium oxide-dispersed mica layer is formed.
Claims (3)
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| JPH10323566A (en) * | 1997-05-23 | 1998-12-08 | Kunio Kitajima | Photocatalyst and its production |
| JPH10323569A (en) * | 1997-05-27 | 1998-12-08 | Kunio Kitajima | Photocatalytic ceramic material and its production |
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