JP4243066B2 - Biofouling prevention material - Google Patents

Description

【００３１】
実施例３
上記実施例１と同様の方法でチタン基材を酸処理した後、塩化白金酸（Ｈ₂ＰｔＣｌ₆・６Ｈ₂Ｏ）、塩化イリジウム酸（Ｈ₂ＩｒＣｌ₆・６Ｈ₂Ｏ）およびタンタルエトキシド（Ｔａ（ＯＣ₂Ｈ₅）₅）をブタノールに個々溶解して、担持物の組成比が７０モル％の白金と１１モル％の酸化イリジウムと１９モル％の酸化タンタルとからなるように配合し、白金（Ｐｔ）とイリジウム（Ｉｒ）とタンタル（Ｔａ）の金属濃度の合計が７０ｇ・ｄｍ^-3である溶液をメスピペットで１ｄｍ²当たり０．４ｃｍ³秤量し、それを上記チタン基材上に塗布した後、室温で３０分間乾燥させ、次いで大気中、５００℃で１０分間焼成した。白金、酸化イリジウム及び酸化タンタルの担持量は金属換算でそれぞれ０．０２ ｇ・ｄｍ^-2、０．００３ｇ・ｄｍ^-2、０．００５ｇ・ｄｍ^-2であった。
以上の工程で、チタン基材表面上に、７０モル％の白金と１１モル％の酸化イリジウムと１９モル％の酸化タンタルの複合体を担持させた生物付着防止材を作製した。
【００３２】
実施例４
上記実施例１と同様の方法でチタン基材を酸処理した後、白金を０．０２ｇ・ｄｍ^-2分散担持させた。
次いで、イリジウム（Ｉｒ）濃度７．５ｇ・ｄｍ^-3である塩化イリジウム酸（Ｈ₂ＩｒＣｌ₆・６Ｈ₂Ｏ）のブタノール溶液をメスピペットで１ｄｍ²当たり０．４ｃｍ³秤量し、それを上記基材上に塗布した後、室温で３０分間乾燥させ、次いで大気中、５００℃で１０分間焼成した。
更に、タンタル（Ｔａ）濃度１２．５ｇ・ｄｍ^-3であるブタノール溶液をメスピペットで１ｄｍ²当たり０．４ｃｍ³秤量し、それを上記基材上に塗布した後、室温で３０分間乾燥させ、次いで大気中、５００℃で１０分間焼成した。酸化イリジウム及び酸化タンタルの担持量は金属換算でそれぞれ０．００３ｇ・ｄｍ^-2、０．００５ｇ・ｄｍ^-2であった。
以上の工程で、チタン基材表面上に、７０モル％の白金と１１モル％の酸化イリジウムと１９モル％の酸化タンタルの複合体を担持した生物付着防止材を作製した。
【００３３】
比較例１〜５
上記実施例３と同様の方法で担持物の割合を表１に示すようにかえて、比較例１〜５を作製した。
【００３４】
＜微生物懸濁液の調整＞
海洋付着細菌ビブリオ・アルギノリチクス（Ｖｉｂｒｉｏ・ａｌｇｉｎｏｌｙｔｉｃｕｓ：ＡＴＣＣ１７７４９）を、マリンブロス（Ｍａｒｉｎｅ ｂｒｏｔｈ）２２１６（ＤＩＦＣＯ Ｌａｂｏｒａｔｏｒｙ社製）中３０℃で１次培養後、１００μｌ採取し２５ｍｌの遠沈管に培地（マリンブロス１５ｍｌ）と共に３０℃、１５０ｒｐｍ、２時間好気的に培養した。培養後の菌体を遠心集菌し、その後滅菌海水で洗浄後滅菌海水中に懸濁させ、菌数をヘマタイトメーターにてカウントし、１×１０⁷ｃｅｌｌ／ｍｌ濃度の菌体懸濁液を作製した。
【００３５】
＜生物付着防止材への微生物付着と電位印加＞
生物付着防止材は、２００ｒｐｍで撹拌した懸濁液中に室温で９０分間浸漬し、生物付着防止材表面に菌体を付着させた。試験槽６に入っている滅菌海水中に浸漬し、２００ｒｐｍの撹拌速度で滅菌海水を撹拌しながら各種電位を印加した。電位印加条件は、図２〜６に示した各パターンを印加した。また、Ｔ１の電位は、０．９ＶｖｓＡｇ／ＡｇＣｌ、６０分間印加とした。Ｔ２の電位は、−０．６ＶｖｓＡｇ／ＡｇＣｌ、３０分間印加とした。Ｔ３の電位は、−０．３Ｖ〜−０．６ＶｖｓＡｇ／ＡｇＣｌ、３０分間印加し、電位を２分間隔で振幅させた。Ｔ４の電位は、−１．４ＶｖｓＡｇ／ＡｇＣｌ、６０分間印加とした。Ｔ５の電位は、−０．３Ｖ〜−１．４ＶｖｓＡｇ／ＡｇＣｌ、６０分間印加し、電位を２分間隔で振幅させた。Ｔ６の電位は、１．６ＶｖｓＡｇ／ＡｇＣｌ、５分間印加とした。
【００３６】
＜微生物の殺菌評価と各工程の効果判定＞
殺菌効果確認と死滅した付着微生物の脱離、洗浄効果の判定には、Ｐｒｏｐｉｄｉｕｍ Ｉｏｄｉｄｅ（ＰＩ）と、４，６−Ｄｉａｍｉｄｉｎｏ−２−Ｐｈｅｎｙｌｉｎｄｏｌｅ（ＤＡＰＩ）の２重染色法により行った。ＰＩとＤＡＰＩは、微生物の細胞膜浸透性の違いにより、微生物の核酸に付着し、青色の蛍光を示すものを生菌体、赤色の蛍光を示すものを死菌体とする微生物の生死判定法として使用されている。また、殺菌された赤色の蛍光を発する微生物の生物付着防止材表面での存在量を比較することによって、スケールや有機物の脱離、洗浄機能の判定を行った。
微生物の染色は、電位を印加した生物付着防止材を滅菌海水で洗浄し、生物付着防止材上の付着菌体をＰＩの２５０μｇ／ｍｌ水溶液、ＤＡＰＩ２０μｇ／ｍｌ水溶液（染色前に調整）を各々３０μｌ滴下して行った。その後、紫外線の励起光を照射し、蛍光顕微鏡観察下で、青色の蛍光を示すものを生菌体、赤色の蛍光を示すものを死菌体として、電位印加前に生物付着防止材上に吸着した菌体数に対する死菌体数により評価した。
尚、判定は、○は殺菌率８０％以上、△は殺菌率２０〜８０％、×は殺菌率２０％未満を示す。
【００３７】
図２〜６の電位印加パターンにおいて、Ｔ１工程を終了後、微生物の殺菌効果を判定した。脱離工程Ｔ２及びＴ３の判定は、電位印加後の付着生物量が殺菌判定後のＴ１工程時からの減少比として、○は減少率７０％以上、△は減少率３０〜７０％、×は減少率３０％未満として示した。Ｔ４、Ｔ５及びＴ６工程の判定は、各パターンのＴ４，Ｔ５及びＴ６工程前の状態と各工程実施後の死菌体の存在有無によって判定した。
尚、試験結果の優位さを判定するため、電位印加時間及び印加電圧については、各種行った。従って、試験結果は、総合的に短時間で、また、完全に低い電位で、等々を考慮した結果を優先することが望ましく、本実施例及び応用例に限定されるものではない。
以下、図２〜６の工程における、実施例１〜４及び比較例１〜５について応用例に基づきその効果を示す。
【００３８】
応用例１
上記装置（図１参照）の生物付着防止材３として、上記実施例１〜４及び比較例１〜５で得た生物付着防止材を用い、印加パターンとして図２に記載したタイミングチャートが示す電位印加パターンを採用した場合のＴ１工程における殺菌率、Ｔ６工程における洗浄率を判定した。結果を表２に示す。
Ｔ１工程では、０．９ＶｖｓＡｇ／ＡｇＣｌを６０分間印加し、殺菌効率を判定した。また、Ｔ１工程のみにて付着していた死細胞の数とＴ６工程を１．０ＶｖｓＡｇ／ＡｇＣｌ、５分間印加とした後に付着していた有機物と見なした死菌体の存在有無によって、分解洗浄効果を判定した。
【００３９】
【表２】

【００４０】
殺菌効果の判定は、○は殺菌率８０％以上、△は殺菌率２０〜８０％、×は殺菌率２０％未満を示す。
分解洗浄効果は、付着死細胞の有無を○は洗浄率８０％以上、△は洗浄率２０〜８０％、×は洗浄率２０％未満を示す。
【００４１】
応用例２
上記装置（図１参照）の生物付着防止材３として、上記実施例１〜４及び比較例１〜５で得た生物付着防止材を用い、印加パターンとして図３、４に記載したタイミングチャートが示す電位印加パターンを採用した場合のＴ２及びＴ３工程における脱離率を判定した。結果を表３に示す。
殺菌効果は、応用例１とほぼ同様の殺菌効率を示していたので、Ｔ１工程で０．９ＶｖｓＡｇ／ＡｇＣｌを１５分間印加し、死菌と生菌が混在して、付着している生物付着防止材を調整した。その後、図３でのＴ２電位は−０．６ＶｖｓＡｇ／ＡｇＣｌ、３０分間印加とし、図４でのＴ３の電位は、−０．３Ｖ〜−０．６ＶｖｓＡｇ／ＡｇＣｌ、３０分間印加し、電位を２分間隔で振幅させた。その際のＴ２工程及びＴ３工程の前後にて、死菌と生菌の総和である付着微生物数に対して、脱離した微生物数の比較し、減少比を求め、脱離効果を判定した。
【００４２】
【表３】

【００４３】
減少率が、○は減少率７０％以上、△は減少率３０〜７０％、×は減少率３０％未満として示した。尚、その後Ｔ６工程を実施した生物付着防止材のすべてで洗浄効果が確認でき、組み合わせによる洗浄促進効果が期待できた。
【００４４】
応用例３
上記装置（図１参照）の生物付着防止材３として、上記実施例１〜４及び比較例１〜５で得た生物付着防止材を用い、印加パターンとして図５、６に記載したタイミングチャートが示す電位印加パターンを採用した場合のＴ４及びＴ５工程における洗浄率を判定した。結果を表４に示す。
殺菌効果は、実施例１とほぼ同様の殺菌効率を示していたので、Ｔ１工程で０．９ＶｖｓＡｇ／ＡｇＣｌを１５分間印加し、死菌と生菌が混在して、付着している生物付着防止材を調整した。その後、Ｔ２電位は−０．６ＶｖｓＡｇ／ＡｇＣｌ、３０分間印加とした。次いで、Ｔ４の電設定を、−１．４ＶｖｓＡｇ／ＡｇＣｌ、１０分間印加とした。また、Ｔ５の電位設定を−０．３Ｖ〜−１．４ＶｖｓＡｇ／ＡｇＣｌ、１０分間印加とし、電位を２分間隔で振幅させた。Ｔ４及びＴ５工程の前後にて、付着していた有機物と見なした死菌体の存在有無によって、洗浄還元効果を判定した。
【００４５】
【表４】

【００４６】
洗浄率が、○は洗浄率７０％以上、△は洗浄率３０〜７０％、×は洗浄率３０％未満として示した。
また、その後Ｔ６工程を実施した場合、短時間で生物付着防止材のすべてでほぼ完全な洗浄効果が確認でき、組み合わせによる洗浄促進効果が期待できた。
【００４７】
応用例４（塩素発生の確認）
実施例１〜４及び比較例１〜５で得た生物付着防止材を、海水５０ｍｌに浸し、１．０Ｖｖｓ．Ａｇ／ＡｇＣｌ以上の電位を印加した場合の海水中の塩素濃度を測定した。電位を印加した海水中の塩素濃度は、残留塩素電極（９７・７０ＢＮ；ＯｒｉｏｎＲｅｓｅａｒｃｈ社製）を用いて測定した。電位印加後の海水を１０ｍｌサンプリングし、沃素試薬（Ｏｒｉｏｎ Ｒｅｓｅａｒｃｈ社製）及び酸試薬（ＯｒｉｏｎＲｅｓｅａｒｃｈ社製）をそれぞれ１００μｌ添加し、撹拌した。溶液を２分間放置した後、マルチメーター（８３ＭＵＬＴＩＭＥＴＥＲ；ＦＬＵＫＥ社製）を接続し残留塩素電極により電位を測定し、標準サンプルとの電極電位差から検量線を用いて塩素濃度を求めた。尚、塩素測定限界は、０．２ｐｐｍである。標準サンプルは、残留塩素標準液（ＯｒｉｏｎＲｅｓｅａｒｃｈ社製）、沃素試薬、酸試薬を各々１００μｌ混ぜ２分間撹拌した後、９９００μｌの蒸留水を添加し再度撹拌することにより作成した。
その結果、塩素の発生量については差があったが、実施例１〜４及び比較例１〜５のすべてより塩素の発生が確認された。
【００４８】
【発明の効果】
本発明に係る生物付着防止材は、生物付着防止材と生物との直接電子移動反応を利用した電気化学的防汚方法に用いる生物付着防止材であって、チタン又はチタン合金よりなる基材の表面の一部もしくは全部に、金属換算に基づく６０〜８０モル％の白金と金属換算に基づく１０〜３０モル％の酸化イリジウムと金属換算に基づく１０〜３０モル％の酸化タンタルとの複合体を担持したものであるので電気化学的防汚効果を長期に渡って安定的に得ることが可能である。
【図面の簡単な説明】
【図１】 実施例の装置の模式図である。
【図２】 電位制御のタイミングチャート図である。
【図３】 電位制御のタイミングチャート図である。
【図４】 電位制御のタイミングチャート図である。
【図５】 電位制御のタイミングチャート図である。
【図６】 電位制御のタイミングチャート図である。
【符号の説明】
１ 制御部
２ ポテンショスタット
３ 生物付着防止材
４ 参照極
５ 対極
６ 試験槽
７ 攪拌棒
８ 攪拌器
９ 正電位側電解生成物発生電位
１０ 負電位側電解生成物発生電位
Ｔ１ 電気化学的生成物を発生しない正電位印加工程
Ｔ２ 電気化学的生成物を発生しない負電位印加工程
Ｔ３ 電気化学的生成物を発生しない負電位領域での振幅電位印加工程
Ｔ４ 電気化学的生成物を発生する負電位印加工程
Ｔ５ 電気化学的生成物を発生する／しない負電位領域での振幅電位印加工程
Ｔ６ 電気化学的生成物を発生する正電位印加工程[0001]
BACKGROUND OF THE INVENTION
The present invention is an anti-biofouling prevention method that electrochemically prevents organisms and scales from adhering to offshore structures, ships, water transportation pipes or waterways, fishing nets, heat exchangers, seawater intake screens, etc. Regarding materials.
[0002]
[Prior art]
Many organisms exist in seawater and freshwater, and adhere to the surface of underwater structures, causing various problems. For example, when adhering to a ship or a buoy, a problem of increased propulsion resistance occurs. Moreover, when it adheres to the aquaculture ginger, problems such as inhibition of seawater exchange occur. Furthermore, problems such as deformation of nets occur when attached to fishing nets such as stationary nets.
In addition, microorganisms attached to the pipes and valves of water supply / drainage cause problems such as contaminating people and products through seawater and fresh water.
The general mechanism of biological attachment to the surface of structures in contact with seawater and fresh water is as follows.
First, adherent gram-negative bacteria adsorb to the surface of the structure and secrete a large amount of slime-like substances derived from lipids. Furthermore, Gram-negative bacteria gather and grow in this slime layer to form a microbial coating. In the seawater, large organisms such as algae, shellfish, and barnacles, which are large organisms, adhere to the microbial coating. The attached large creatures will breed and grow, eventually covering the surface of the underwater structure.
As an antifouling means for organisms adhering to the surface of such underwater structures and seawater or fresh water, a bactericidal substance is added to the antifouling surface, or a paint film containing an organotin compound is used. In general, an organic tin-based compound is eluted and an antifouling method using chlorine generated by electrolyzing seawater is generally performed. However, these methods generate harmful substances, and there is a concern about the impact on the organism due to water pollution.
[0003]
In recent years, methods have been proposed for controlling organisms attached to the surface of an underwater structure, seawater, or fresh water that is electrochemically contacted without generating harmful substances.
In this electrochemical biological control method, when a potential higher than a predetermined potential at which a direct electrochemical reaction with a microorganism is confirmed is applied to the microorganism, the redox substance inside the microorganism is irreversibly oxidized, and the respiration of the microorganism It is possible to induce a decrease in the activity and the permeability barrier of the microbial membrane and kill the microorganism (Japanese Patent Publication No. 6-91821). Incidentally, in the marine-adherent bacterium Vibrio arginolyticus used in the present invention, 0.7 Vvs. The oxidation peak current can be confirmed by SCE. In other words, since the predetermined potential at which direct electrochemical reaction with microorganisms is confirmed occurs below the decomposition potential of fresh water or seawater that is the electrolyte, there is no production of chemical substances and only microorganisms that adhere to the conductive substrate are sterilized. It is possible to prevent the subsequent attachment of aquatic organisms. Therefore, it has been shown that this is an excellent antifouling method that is free from marine pollution and has no effect on the ecosystem of marine organisms.
Japanese Patent Application Laid-Open No. 11-19249 discloses a step of applying a positive potential to a conductive substrate in water to adsorb and sterilize microorganisms in the water on the surface of the conductive substrate; A step of destroying microorganism cells adsorbed on the surface of the conductive substrate by applying a higher positive potential, and detaching the sterilized microorganisms adhered to the conductive substrate and their decomposition products; An invention having a gist of a method for controlling an underwater microorganism characterized by the above is described. Further, in Japanese Patent No. 3105024, in water, a positive potential is applied to the conductive substrate to adsorb and sterilize microorganisms in water on the surface of the conductive substrate (+0 to 1.5 V vs SCE), A step of detaching sterilized microorganisms adsorbed on the surface of the conductive substrate by applying a negative potential to the conductive substrate (−0 to 0.4 V vs. SCE). An invention based on the control method is described. JP 2001-198572 A discloses a step of adsorbing and sterilizing microorganisms in water on the surface of the conductive substrate by applying a positive potential that does not cause electrolysis to the conductive substrate in water. A negative potential that causes electrolysis is applied to the conductive substrate to reduce the surface of the conductive substrate, and a sterilized microorganism that induces an alkaline substance to the surface of the conductive substrate and is adsorbed on the surface of the conductive substrate, and its The present invention describes a method for controlling an underwater microorganism characterized by performing a step of detaching a degradation product.
Furthermore, as an approximate antifouling method, a method of generating antifouling by generating oxygen in a conductive substrate is disclosed in Japanese Patent Publication No. 1-46595 and Japanese Patent Application Laid-Open No. 11-303041. In these methods, the oxygen generation potential is in the range of about 0.55 V to 1.1 V. However, in the electrochemical antifouling method, microorganisms can be sterilized only when the cell and the conductive substrate are in direct contact. However, there is no clear proof that oxygen generated at almost the same potential can sterilize and prevent soiling microorganisms that do not contact the conductive substrate. Therefore, conceptual separation from the electrochemical antifouling method is difficult for microorganisms and the like not to adhere to the conductive substrate.
Further, antifouling methods for generating hypochlorite ions and chlorine ions by applying a positive potential to the conductive coating film are described in Japanese Patent Publication No. 6-15069 and Japanese Patent Publication No. 8-14036. It is considered that the antifouling effect by the chlorine injection method by the seawater electrolyzer is achieved by generating chlorine directly on the antifouling surface.
[0004]
[Problems to be solved by the invention]
The method of sterilizing microorganisms and preventing adhesion by applying a potential that does not cause electrolysis of seawater or fresh water to the biological anti-adhesive material is free from marine pollution and has no impact on the ecosystem of marine organisms. It is an excellent antifouling method.
By the way, the above-mentioned electrochemical antifouling method was sterilized by applying a positive potential that does not cause electrolysis of seawater or freshwater to sterilize adhering microorganisms, and applied a negative potential that does not cause electrolysis of seawater or freshwater. It consists of a step of removing microorganisms, charged organic substances and scales, and a step of washing and reducing the surface to be protected by applying a negative potential that causes electrolysis of seawater and fresh water. In the electrochemical antifouling method, in order to maintain the effect for a long period of time, it is necessary to wash and reduce the biofouling prevention material as the antifouling surface so that the sterilization step can be sufficiently performed by the washing step.
On the other hand, during the cleaning process, the sterilization process and the desorption process cannot be performed, and precipitation of magnesium hydroxide or the like occurs on the surface of the bioadhesion prevention material, thereby inhibiting the electron transfer reaction. The time distribution of each process needs to be changed according to the environment. In addition, when the biofouling prevention material that is the surface to be protected is excessively oxidized, the rate of electron transfer between the microorganism and the biofouling prevention material is reduced due to an increase in the electrical resistance value on the surface of the biofouling prevention material. May occur, or it may be difficult to apply the set potential uniformly to the entire antifouling organism adhesion prevention material. In addition, the surface of the bioadhesion preventing material has problems such as a decrease in function as an electrode accompanying deterioration of a constituent material.
[0005]
[Means for Solving the Problems]
The present invention has been made in view of these problems, and while maintaining and improving the function as an electrode of a biofouling prevention material as an antifouling surface, the electrochemical antifouling effect of the whole antifouling biofouling prevention material is prolonged. The aim is to obtain a stable environment.
The present inventionA biofouling prevention material used in an electrochemical antifouling method using a direct electron transfer reaction between a biofouling prevention material and a living organism,60 to 80 mol% platinum based on metal conversion, 10 to 30 mol% iridium oxide based on metal conversion, and 10 to 30 mol based on metal conversion on a part or all of the surface of the substrate made of titanium or titanium alloy The gist of the present invention is a bioadhesion-preventing material characterized in that it carries a composite with a 50% tantalum oxide.
[0006]
Hereinafter, the present invention will be described in detail.
The biofouling prevention material according to the present invention is part or all of the substrate surface made of titanium or a titanium alloy,A composite of 60 to 80 mol% platinum based on metal, 10 to 30 mol% iridium oxide based on metal, and 10 to 30 mol% tantalum oxide based on metal is supported.
In the titanium or titanium alloy used as the base material, a corrosion-resistant conductive alloy mainly composed of titanium is used as the titanium alloy. For example, titanium-tantalum-niobium (Ti-Ta-Nb), titanium-palladium ( Ti-Pd), titanium-zirconium (Ti-Zr), titanium-aluminum (Ti-Al), and other titanium-based alloys that are usually used as electrode materials.
This bio-adhesion prevention material may be any material that can adsorb aquatic organisms efficiently and directly or indirectly, and can apply an electric potential, and is processed into a desired shape such as a plate shape, a perforated plate shape, a rod shape, or a plate net shape. The structure is not particularly limited as long as it has a function of maintaining the structure.
A base material made of titanium or a titanium alloy used in the present invention is coated with or laminated with conductive fine particles according to a commonly used method when manufacturing an electrode for seawater electrolysis or an oxygen generating electrode. Can be used. When coating and laminating, it is necessary to consider such as improving the adhesion between the fine particles of the conductive material and the substrate.
[0007]
Based on metal conversion on part or all of substrate surface60-80Based on mole percent platinum and metal equivalents10-30Based on mole percent iridium oxide and metal equivalents10-30The biofouling prevention material carrying a complex with mol% tantalum oxide is directly or indirectly brought into contact with the surface of the biofouling prevention material by applying a positive potential without generation of oxygen or chlorine from water or seawater. Sterilizes aquatic organisms, suppresses growth, generates chlorine compounds or radicals from water, seawater, etc., and removes and attaches aquatic organisms and scales that directly or indirectly come into contact with the antifouling material surface and biofouling Preventive materials can be reactivated.
When the electrolyte is seawater, the composition ratio of the composite of platinum, iridium oxide, and tantalum oxide is preferably adjusted so that the chlorine overvoltage is a positive potential lower than the oxygen overvoltage.
When the electrolytic solution is water that does not contain a chlorine compound, the composition ratio of the composite of platinum, iridium oxide, and tantalum oxide is preferably adjusted so that the oxygen overvoltage becomes a positive potential lower than the chlorine overvoltage.
[0008]
It is desirable to pre-treat titanium or a titanium alloy (hereinafter referred to as a titanium base material) used in the present invention in advance as usual. Specific examples of such pretreatment include the following.
First, after degreasing the surface of the titanium substrate according to a conventional method, for example, washing with alcohol or the like and / or electrolysis in an alkaline aqueous solution, the hydrogen fluoride concentration is in the range of 1 to 20% by weight, particularly 5 to 10% by weight. By treating with hydrofluoric acid or mixed acid of hydrofluoric acid and other acids such as nitric acid and sulfuric acid, the oxide film on the surface of the titanium substrate is removed and the surface of the titanium grain boundary is roughened. I do. The acid treatment can be performed at a temperature of from room temperature to about 40 ° C. for a few minutes to a few dozen minutes depending on the surface condition of the titanium substrate. A blasting process may be used in combination for sufficient roughening.
The surface of the titanium substrate treated in this way is brought into contact with concentrated sulfuric acid, and the inner surface of the titanium crystal grain boundary is finely roughened into a projection and a thin film of titanium hydride is formed on the surface of the titanium substrate. To do.
Concentrated sulfuric acid to be used generally has a concentration of about 40 to 80% by weight, preferably about 50 to 60% by weight, and this concentrated sulfuric acid has a small amount of sodium sulfate or the like for the purpose of stabilizing the treatment if necessary. Or a sulfate thereof may be added. The contact with the concentrated sulfuric acid can be usually carried out by immersing the titanium substrate in a concentrated sulfuric acid bath, and the bath temperature is generally in the range of about 100 to 150 ° C., preferably in the range of about 110 to 130 ° C. The immersion time is usually about 0.5 to 10 minutes, preferably about 1 to 3 minutes. By this sulfuric acid treatment, the inner surface of the titanium crystal grain boundary can be finely roughened in a protruding shape, and a very thin titanium hydride coating can be formed on the surface of the titanium substrate.
The sulfuric acid-treated titanium base material is taken out of the sulfuric acid bath and preferably cooled rapidly in an inert gas atmosphere such as nitrogen or argon to lower the surface temperature of the titanium base material to about 60 ° C. or lower. It is appropriate to use a large amount of cold water for this cold water also for washing.
In this way, the titanium substrate on which a very thin titanium hydride film is formed is dipped in dilute hydrofluoric acid or dilute fluoride aqueous solution (for example, sodium fluoride, potassium fluoride, etc.) to perform the hydrogenation. A titanium film is grown to make the film uniform and stable. The concentration of hydrogen fluoride in the dilute hydrofluoric acid or dilute aqueous solution that can be used here is generally 0.05 to 3% by weight, preferably 0.3 to 1% by weight, The temperature during the immersion treatment with these solutions is generally in the range of 10 to 40 ° C, preferably 20 to 30 ° C. The treatment can be carried out until a uniform film of titanium hydride having a thickness of usually 0.5 to 10 μm, preferably 1 to 3 μm is formed on the surface of the titanium substrate. Since this titanium hydride (TiHy, where y is a number between 1.5 and 2) exhibits a grayish brown color to a blackish brown color depending on the degree of hydrogenation, a titanium hydride film having a thickness in the above range is formed. Can empirically control the change in the color of the surface of the substrate by contrasting with the standard color source and brightness.
[0009]
The surface of the titanium base material thus roughened and the titanium hydride film formed on the surface of the titanium base material,60-80With mol% platinum10-30With mol% iridium oxide10-30A composite of mol% tantalum oxide is supported. The composite as used herein refers to a composite or intimate contact with platinum, iridium oxide, and tantalum oxide so as to interact with each other. At this time, the mixture may be supported simultaneously, platinum may be supported before the oxide, or may be individually supported. In addition, when supporting individually, it is preferable to carry | support tantalum which is the same family as a base material last, in order to raise the adhesiveness to the base material of platinum and iridium. Therefore, it is preferable to carry platinum, iridium oxide, and tantalum oxide in this order.
[0010]
Hereinafter, the case where platinum is supported prior to the oxide will be specifically described.
As described above, platinum is dispersed and supported on the surface of the titanium base material on which the surface is roughened and the titanium hydride film is formed. This platinum dispersion support can usually be carried out by electroplating. Examples of the composition of the plating bath that can be used in this electroplating method include platinum compounds such as chloroplatinic acid, ammonium chloroplatinate, potassium chloroplatinate, and dinitrodiaminoplatinum in sulfuric acid solution (pH 1 to 3) or aqueous ammonia solution ( pH 11-13) about 2-20 g · dm in terms of platinum^-3, Preferably about 5 to 15 g · dm^-3In order to stabilize the bath, if necessary, add a small amount of sodium sulfate (in the case of an acidic bath), sodium sulfite, sodium sulfate (in the case of an alkaline bath), etc. Or an alkaline plating bath is mentioned. Platinum electroplating using a plating bath having such a composition should be performed at a relatively low temperature within a range of about 30 to 60 ° C. in order to suppress decomposition of the titanium hydride coating formed on the surface of the titanium base as much as possible. desirable.
By this electroplating, platinum dispersed on the titanium hydride film of the titanium base material can be supported. In this case, the dispersion state of platinum can be controlled, for example, by empirically adjusting the composition of the platinum plating bath and / or plating conditions (current density and current waveform).
Thus, platinum dispersed to such an extent that the surface of the base material is partially exposed is supported on the titanium base material. When the state of dispersion is observed with an electron microscope of 5,000 times, it can be seen that platinum is dispersed in the form of dots, lines, and networks on the surface of the titanium substrate. The amount of platinum deposited is 0.1 to 20 g · m.^-2, Preferably 1 to 5 g · m^-2It can be.
The degree of platinum dispersion support is 10 to 80%, preferably 30 to 60% in terms of coverage. If the platinum coverage is too low, the stability of the antifouling effect is deteriorated. On the other hand, if the platinum coverage is too high, the adhesion strength of the mixed oxide described later becomes unstable. In the present specification, the “coverage” of platinum is obtained by taking a 40,000-fold electron micrograph of the surface of a titanium base material on which platinum is dispersed and supported.²This is a value calculated by the following equation after measuring the area of platinum covered per unit.
  Coverage ratio (%) = 100 × (platinum covered area on the photographic plane) / (titanium substrate area on the photographic plane)
  As described above, the surface of the titanium base material on which platinum is dispersed and supported is then calcined in the atmosphere, if necessary, to thermally decompose the titanium hydride film, so that the titanium hydride is substantially made of titanium metal. In addition, the titanium in the vicinity of the boundary with the platinum carrier can be changed to titanium oxide in a low oxidation state. This calcination can be generally performed by heating in the atmosphere at a temperature of about 300 to 600 ° C., preferably about 300 to 400 ° C. for about 10 minutes to 4 hours. As a result, a very thin conductive titanium oxide layer is formed on the surface of the titanium substrate. The thickness of the titanium oxide layer is generally within the range of 10 to 100 nm, preferably 20 to 60 nm. Further, the composition of the titanium oxide is such that x is generally 1 <x <2, especially 1. It is desirable that the range is 9 <x <2.
As another method, the titanium base material on which platinum is dispersed and supported may be directly subjected to the next step without performing the heat treatment as described above. In this case, the titanium hydride film on the surface of the titanium substrate is converted into titanium metal and titanium oxide in a low oxidation state during firing of the oxide in the next step.
[0011]
Thereafter, a mixed oxide of iridium oxide and tantalum oxide is supported on the surface of the titanium base material on which platinum thus heat treated is dispersed and supported. The supported ratio of platinum, iridium oxide, and tantalum oxide at this time is a metal-converted molar ratio of Pt / Ir / Ta.It is preferable to be in the range of 60 to 80/10 to 30/10 to 30.
As described above, the iridium compound and the tantalum compound are adhered to the surface of the base material by applying a solution containing an iridium compound and a tantalum compound, preferably a lower alcohol solution, and then drying on the surface of the titanium base material on which platinum is dispersed and supported. Let me. Examples of the iridium compound and the tantalum compound that can be used here include compounds soluble in a lower alcohol solvent that can be thermally decomposed under the firing conditions described later and converted into iridium oxide and tantalum oxide, respectively. Examples of such iridium compounds include iridium chloride, iridium chloride, and potassium iridium chloride. Examples of tantalum compounds include tantalum chloride and tantalum ethoxide.
On the other hand, examples of lower alcohols that can dissolve these iridium compounds and tantalum compounds include methanol, ethanol, propanol, isopropanol, butanol, and mixtures thereof.
The application of the solution onto the surface of the titanium base material on which platinum is dispersed and supported can be performed, for example, by a spraying method, a brush coating method, a dipping method, or the like. In this way, a lower alcohol solution of an iridium compound and a tantalum compound. The titanium substrate to which is applied is dried at a relatively low temperature in the range of about 20 to 100 ° C. and then fired in an oxidizing atmosphere, usually in the air.
The processing described above can be repeated until the loading amount reaches the above range. The calcination can be carried out by heating to a temperature generally in the range of about 450 to 650 ° C., preferably about 500 to 600 ° C. in a suitable heating furnace such as an electric furnace, a gas furnace or an infrared furnace. . The heating time at that time can be about 5 minutes to 2 hours, depending on the size of the substrate to be fired. By this firing, the iridium compound and the tantalum compound are changed to iridium oxide and tantalum oxide, respectively, and the platinum-iridium oxide-tantalum oxide composite can be supported on the titanium substrate.
[0012]
Next, the case where platinum, iridium oxide, and tantalum oxide are simultaneously supported on the surface of a titanium base material that has been roughened and formed with a titanium hydride film will be described in detail.
The platinum compound, iridium compound and tantalum compound used here are compounds that can be decomposed and converted to platinum, iridium oxide and tantalum oxide, respectively, under the conditions described below. Examples of the platinum compounds include chloroplatinic acid and platinum chloride. And dinitrodiaminoplatinum. Examples of iridium compounds include iridium chloride, iridium chloride, and potassium iridium chloride. Examples of tantalum compounds include tantalum chloride and tantalum ethoxide.
On the other hand, as a solvent for dissolving these platinum compounds, iridium compounds and tantalum compounds, lower alcohols are suitable, and for example, methanol, ethanol, propanol, butanol or a mixture thereof is used. Since dinitrodiaminoplatinum does not dissolve directly in lower alcohols, it is first dissolved in an aqueous nitric acid solution and converted to 250 to 450 g · dm in terms of platinum metal.^-3It is preferable to dissolve in a lower alcohol after adjusting to the concentration.
The total metal concentration of the platinum compound, iridium compound and tantalum compound in the lower alcohol solution is generally 2 to 200 g · dm.^-3, Preferably 20 to 100 g · dm^-3Can be within the range. The metal concentration is 2 g · dm^-3If it is lower, the loading efficiency becomes worse, and 200 g · dm.^-3If it exceeds 1, aggregation tends to occur at the time of firing, causing problems such as non-uniformity in the carrying strength and carrying amount.
[0013]
The above solution is applied onto the surface of the titanium base material that has been roughened and formed with a titanium hydride film, dried at a relatively low temperature in the range of about 20 to 100 ° C., and then in an oxidizing atmosphere, for example, Bake in the atmosphere. Firing can be performed by heating to a temperature generally in the range of about 450 to 650 ° C., preferably about 500 to 600 ° C. in a suitable heating furnace such as an electric furnace, a gas furnace or an infrared furnace. The heating time at that time can be about 5 minutes to 2 hours, depending on the size of the substrate to be fired. By this firing, a platinum-iridium oxide-tantalum oxide composite can be supported on the surface of the titanium substrate.
When a predetermined platinum-iridium oxide-tantalum oxide composite cannot be supported by a single supporting operation, the above-described solution application-drying-firing process can be repeated a desired number of times. it can.
[0014]
The antifouling apparatus using the biofouling prevention material according to the present invention is provided with a counter electrode so as not to contact the biofouling prevention material. The counter electrode base material may be the same as the biological adhesion preventing material. Moreover, it can also select suitably according to the physical property and shape of a to-be-stained surface. Moreover, the biological adhesion preventing material and the counter electrode are not particularly limited as long as they are arranged to the extent that the biological adhesion preventing material and the microorganisms react electrochemically.
[0015]
The biological adhesion preventing material and the counter electrode are connected to the power supply device by lead wires. This power supply device is a device that applies a direct current between the biological adhesion preventing material and the counter electrode, and preferably has a function of converting the polarity. In addition, when there are few organisms living in water or seawater to the extent that antifouling can be maintained simply by applying a potential higher than the potential at which the direct electron transfer reaction between the electrode and the microorganism occurs, a constant current generator (galvano (Stat) can be used.
The potentiostat and galvanostat that can be used are not particularly limited as long as a predetermined potential can be applied to the biological adhesion preventing material or a constant current can flow. In particular, it is preferable to implement a DC power supply device to which voltage control or current control and timing control means are added.
[0016]
Furthermore, a reference electrode can be used as necessary.
It is preferable to install the reference electrode in the vicinity of the working electrode. However, if the current value when the antifouling effect is manifested between the bioadhesion prevention material and the counter electrode is clear, the reference electrode should not be used. There is no problem.
[0017]
The basic antifouling function expression configuration in the electrochemical antifouling method according to the present invention is:
(1) Sterilization step: a step of sterilization by applying a positive potential that does not generate a product electrochemically from the electrolyte in the biological adhesion prevention material (+0 to 1.5 V vs SCE);
(2) Desorption step: A negative potential that does not generate a product electrochemically from the electrolyte is applied to the biofouling prevention material, and aquatic organisms and scales that directly or indirectly adhere to contact with each other are electrostatically functioned. A desorption step (−0 to −0.6 V vs SCE);
(3) Washing and reducing step: Applying a negative potential to electrochemically generate a product from the electrolyte to the biofouling prevention material, alkaline decomposition and washing of aquatic organisms and scales attached to and contacted with the biofouling prevention material Reducing the biofouling prevention material surface (−0.6 to −2.0 V vs SCE);
(4) Decomposition cleaning reactivation step: A positive potential for electrochemically generating a product from the electrolytic solution is applied to the biofouling prevention material, and the biofouling prevention material adheres directly or indirectly to the surface. Aquatic organisms and scales are desorbed and washed by generation of chlorine compounds or radicals, and the surface of the biofouling prevention material is cleaned and reactivated (positive potential higher than +1.5 V vs SCE),
Implement any process on the anti-fouling surface biofouling prevention material so that the load on water and seawater caused by the most chemically generated chemical substances is minimal, and the long-term antifouling effect is stably obtained. It is.
However, these potentials can be changed by a reference electrode for measuring a reference potential of water or seawater, or a combination of the bio-adhesion preventing material and the counter electrode material as the anti-stain surface to be used. For example, as a reference electrode, a reference electrode generally used for electrochemical measurement such as SCE (saturated citrus electrode) or Ag / AgCl (silver / silver chloride electrode) can be used.
[0018]
Next, potential application conditions in each step will be described.
(1) Sterilization process
When a positive potential is applied to the biofouling prevention material in water containing aquatic organisms, the aquatic life in the water is adsorbed on the surface of the biofouling prevention material. Furthermore, the positive potential applied to the biofouling prevention material has an action of electrochemically sterilizing aquatic organisms that have adsorbed and contacted the surface of the biofouling prevention material. In other words, aquatic organisms are adsorbed on the surface of the biological adhesion preventing material by a positive potential and sterilized on the surface. At this time, the set potential is a potential at which no product is generated electrochemically from the electrolytic solution, and is a potential equal to or lower than the generation potential of oxygen and chlorine accompanying the decomposition of water and seawater.
The preferred potential is +0 to 1.5 V vs. SCE, more preferably +0.5 to +1.2 Vvs. SCE. However, this potential depends on the physical properties of the biofouling prevention material used. If the potential is below the generation potential of oxygen or chlorine accompanying water decomposition, contamination of water and seawater by electrolytic products is not possible. It can be suppressed to a minimum and can exhibit a stable antifouling effect over a long period of time. Also, +0 Vvs. Although the aquatic organisms cannot be adsorbed on the substrate and sterilized if the direct electron transfer reaction with the microorganism is confirmed from the SCE, the potential can be intermittently applied in consideration of deterioration and consumption of the biofouling prevention material. It is preferable to vary.
The time for applying a positive potential at which no product is electrochemically generated from the electrolyte can be selected as appropriate depending on the characteristics of the biofouling prevention material. Generally, the antifouling effect is maintained for several years, even if it is about 0.5-24 hours, depending on the durability of the biofouling prevention material and the amount of aquatic organisms directly or indirectly contacting the surface of the biofouling prevention material. If so, it is preferable to set as long as possible per unit time because the load on the water and seawater by the electrolytically generated chemical substance is small. Depending on the biofouling preventive material, application for 0.1 to 1000 hours is more preferable, depending on the oxide formation rate.
[0019]
(2) Desorption process
Next, when a negative potential is applied to the surface of the biofouling prevention material, aquatic organisms and scales that are in direct or indirect contact with each other are detached. The negative potential at which no product is electrochemically generated from the electrolyte is 0 to -1.0 Vvs. Ag / AgCl. Preferably, −0 to −0.6 Vvs. Ag / AgCl. At that time, aquatic organisms, other cells, cells of sterilized aquatic organisms and / or damaged or organic matter adhered to the biofouling preventive material may have a pH on the surface of the biofouling preventive material due to electrostatic mechanism or potential fluctuation. Desorbed due to fluctuations.
Furthermore, desorption and washing can be made more efficient by changing the potential at the negative potential. The width of the varying potential is preferably about −0.3 V to −0.9 V, and the period is preferably 10 Hz to 0.001 Hz.
The time for applying a negative potential at which no product is electrochemically generated from the electrolytic solution can be appropriately selected depending on the characteristics of the biofouling prevention material. Generally, it varies depending on the durability of the biofouling preventive material and the amount of aquatic organisms directly or indirectly in contact with the surface of the biofouling preventive material, but is preferably about 0.1 to 24 hours. In consideration of deterioration of the biofouling prevention material, application for 0.1 to 2 hours is more preferable.
[0020]
(3) (Washing reduction process)
Furthermore, the negative potential at which an electrochemical product is generated from an electrolyte such as water or seawater is −1.0 Vvs. More negative potential than Ag / AgCl, preferably -1.0 V to -2.0 Vvs. It is about Ag / AgCl. By applying this negative potential, detachment of aquatic organisms, other cells, sterilized aquatic organism cells adhering to the biofouling prevention material, and / or their breakage or organic matter is promoted. When a negative potential is generated that electrochemically generates a product from the electrolyte, hydrogen is generated on the surface of the biofouling prevention material due to the decomposition of the electrolyte, and this hydrogen removes the deposit on the surface of the biofouling prevention material. It is to be done. Moreover, pH becomes alkaline in the vicinity of the biological adhesion preventing material. Furthermore, the precipitation of hydroxide may occur due to the strong alkali atmosphere, and it is necessary to appropriately select the potential to be applied and the application time. However, the organic substance is dissolved by the hydroxide. By removing and dissolving them, the surface of the biofouling prevention material is cleaned. Further, it may be necessary to reduce the oxide on the surface of the bioadhesion preventive material, reduce the oxide that inhibits the electron transfer reaction at the bioadhesion preventive material interface, and maintain and recover the function of the sterilization process. Furthermore, desorption and washing can be made more efficient by changing the potential at the negative potential. The width of the changing potential is preferably about −0.3 V to −2 V, and the period is preferably 10 Hz to 0.001 Hz.
The time for applying a negative potential at which a product is generated electrochemically from the electrolyte can be selected as appropriate depending on the characteristics of the biofouling prevention material. In general, it varies depending on the durability of the biofouling prevention material and the amount of aquatic organisms that directly or indirectly contact the surface of the biofouling prevention material, but is preferably about 0.5 to 24 hours. In consideration of deterioration of the biofouling prevention material, application for 0.5 to 2 hours is more preferable.
[0021]
(4) (Decomposition cleaning reactivation process)
The potential at which the product is electrochemically generated from the electrolyte is a potential at which oxygen or chlorine is generated as water or seawater decomposes, and is +1.5 Vvs. This is clearly confirmed by the potential exceeding Ag / AgCl. When these high potentials are applied for a long time, water and seawater are likely to be electrolyzed to generate chlorine and unknown substances, and the biofouling prevention material may deteriorate, so it is stable for a long time. In particular, it may be inappropriate to maintain the antifouling effect and to minimize the contamination of water and seawater by electrolytic products.
However, in the present invention for the purpose of antifouling for a long period of time, sterilized microorganisms, organic matter, and scales that cannot be excluded even when various potentials are applied may adhere to the surface of the biofouling prevention material that becomes the surface to be protected. In order to re-activate them and reproduce the antifouling effect for a long period of time without the cost of replacing biofouling prevention materials, it is preferable to control the minimum necessary chlorine compound and radical generation function.
Incidentally, when the physical property of the surface of the bioadhesion preventive material is such that the chlorine overvoltage is lower than the oxygen overvoltage, a chlorine compound is generated, and if the reverse is true, a phenomenon in which oxygen is generated first can be confirmed.
The time for applying a positive potential for electrochemically generating a product from the electrolytic solution can be appropriately selected depending on the characteristics of the bioadhesion preventing material. In general, the durability of biofouling prevention materials varies depending on the amount of aquatic organisms that are directly or indirectly in contact with the surface of the biofouling prevention material. It is preferable to set to minimize the above. Considering this point, it is more preferable to apply about 0.5 to 24 hours per month. Moreover, it is also possible to set and operate for the time of about 1/10 to 1 / 10,000 compared with the set time of the sterilization process of (1).
[0022]
In the present invention, in order to minimize contamination of water and seawater by chemical substances and maintain the antifouling effect over a long period of time, the above (1) sterilization step, (2) desorption step, (3) washing reduction step, (4) Each step of the decomposition cleaning reactivation step can be applied periodically in an arbitrary order and frequency according to the situation after appropriately setting the applied potential and the applied time.
[0023]
The electrolyte solution that can be treated according to the present invention is not particularly limited as long as it is water containing organisms. For example, seawater, river water, lake water, tap water, drinking water, or various buffer solutions may be used. In addition, the target organism is not particularly limited as long as it is an organism present in the water.
[0024]
[Action]
The biological adhesion preventing material according to the present invention isA biofouling prevention material used in an electrochemical antifouling method using a direct electron transfer reaction between a biofouling prevention material and a living organism,60 to 80 mol% platinum based on metal conversion, 10 to 30 mol% iridium oxide based on metal conversion, and 10 to 30 mol based on metal conversion on a part or all of the surface of the substrate made of titanium or titanium alloy Since it is a bioadhesion prevention material characterized by carrying a composite with a tantalum oxide ofApply at least a positive potential that does not electrochemically generate a product from the electrolytic solution to the biofouling prevention material,The growth of aquatic organisms that directly or indirectly come into contact with the surface of the biofouling prevention material can be suppressed. The bioadhesion preventive material, a counter electrode, and a power source that applies a voltage between the bioadhesion preventive material and the counter electrode, and the aquatic organism that directly or indirectly contacts the bioadhesion preventive material surface, By applying a positive potential for electrochemically generating a product from the electrolyte in the biofouling prevention material by an electrochemical antifouling device that controls a direct electron transfer reaction with the biofouling prevention material, A process for detaching and cleaning aquatic organisms and scales that directly or indirectly contact the surface of the anti-adhesion material and reactivating the bio-adhesion prevention material can be set. The positive potential at which no electrochemical product is generated from the electrolyte, the negative potential at which no electrochemical product is generated from the electrolytic solution, and the negative potential at which electrochemical product is generated from the electrolytic solution And can be set arbitrarily And it can be periodically applied.
[0025]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
FIG. 1 is a schematic view of an apparatus used in the following examples.
In the test tank 6, the biological adhesion preventing material 3, the reference electrode 4, and the counter electrode 5 are arranged. The potentiostat 2 is individually connected to each of the biofouling prevention material 3, the reference electrode 4, and the counter electrode 5. The test tank 6 contains sterilized seawater, and a stirrer 8 and a stirring bar 7 are disposed at the bottom thereof. A silver / silver chloride electrode (Ag / AgCl) was used for the reference electrode 4, and an electrode formed of a conductive material was used for the counter electrode 5.
The control unit 1 outputs an instruction value of the applied potential to the reference electrode 4 of the biofouling prevention material 3 in an analog manner, and the potentiostat 2 causes the potential of the biological adhesion prevention material 3 to the reference electrode 4 to be an analog input value. The voltage is output to the biological adhesion preventing material 3 and the counter electrode 5. In order to change the potential, the control unit 1 outputs an analog output of the indication value of the applied potential with a time resolution of at least 100 Hz, preferably 1 kHz or more. Furthermore, the potentiostat 2 responds to the analog input value of the potential accordingly with a response performance of at least 100 Hz, preferably 1 kHz or more.
The control unit 1 includes a circuit configured by a CPU, an input / output port, a digital / analog converter, and a memory (not shown) such as a ROM or a RAM. A control program and a timing chart for control to be described later are incorporated in the ROM, and the CPU converts the potential indication value into an analog value by a digital / analog converter according to the control program and the timing chart, and outputs the result to the potentiostat 2. . By using a one-chip computer incorporating the above-described components in the control unit 1, the overall circuit configuration can be simplified and made inexpensive.
[0026]
Next, the timing chart of potential control shown in FIG. 2 will be described in detail. In the timing chart, the horizontal axis indicates time, and the vertical axis indicates an indication value of the potential with respect to the reference electrode 4 of the biological adhesion preventing material 3. Here, a combination of the following four types of steps (six potential application steps) is explicitly illustrated as a timing chart, but other steps depending on how to apply a potential are not specifically excluded.
(1) (Sterilization step) Positive potential application step (T1) that does not generate an electrochemical product: A step of applying a positive potential lower than the positive potential side electrolysis product generation potential 9. The potential value to be applied can be changed depending on the process.
(2) (Desorption step) Negative potential application step (T2) that does not generate electrochemical products or amplitude potential application step (T3) in a negative potential region that does not generate electrochemical products: Both steps are negative A negative potential higher than the potential side electrolytic product generation potential 10 is applied. In the amplitude potential application step (T3), the applied potential is changed almost continuously. Depending on the responsiveness of the system, it is possible to give a potential changed in a trapezoidal wave instead of a triangular wave as the indication potential.
(3) (Washing reduction step) A negative potential applying step (T4) for generating an electrochemical product, or an amplitude potential applying step in a negative potential region where an electrochemical product is generated and / or a negative potential region where no electrochemical product is generated ( T5): In both steps, a negative potential lower than the negative potential side electrolysis product generation potential 10 is applied.
(4) (Decomposition cleaning reactivation step) Positive potential application step (T6) for generating an electrochemical product: A positive potential higher than the positive side electrolysis product generation potential 9 is applied.
  In the potential application pattern shown in the timing chart of FIG. 2, the positive potential application step (T1) that does not generate an electrochemical product and the positive potential application step (T6) that generates an electrochemical product are alternately repeated. The application potential and application period of each process can be determined appropriately according to the case. For example, a pattern in which a plurality of different potential values are applied in the positive potential application process (T1) that does not generate an electrochemical product can be created. It is.
In the potential application pattern shown in the timing chart of FIG. 3, a positive potential application step (T1) that does not generate an electrochemical product, a negative potential application step (T2) that does not generate an electrochemical product, and an electrochemical product. The positive potential applying step (T6) for generating is alternately repeated. The applied potential and the application period in each step can be appropriately determined according to circumstances, and the order and frequency are also arbitrary. For example, a positive potential application step (T1) that does not generate an electrochemical product and a negative potential application step (T2) that does not generate an electrochemical product are alternately repeated a certain number of times, and then an electrochemical product is generated. A pattern of applying the positive potential applying step (T6) can be created.
In the potential application pattern shown in the timing chart of FIG. 4, a positive potential application step (T1) that does not generate an electrochemical product, an amplitude potential application step (T3) in a negative potential region that does not generate an electrochemical product, and The positive potential application step (T6) for generating the electrochemical product is repeated alternately. The applied potential and the application period in each step can be appropriately determined according to circumstances, and the order and frequency are also arbitrary. The amplitude and change rate of the potential in the amplitude potential application step (T3) in the negative potential region where no electrochemical product is generated should be set within a range in which the controller 1 can output, although it depends on the responsiveness of the system. Can do. As in FIG. 3, for example, a positive potential applying step (T1) that does not generate an electrochemical product and an amplitude potential applying step (T3) in a negative potential region that does not generate an electrochemical product are alternately repeated a certain number of times. Then, it is also possible to create a pattern in which a positive potential application step (T6) for generating an electrochemical product is applied.
[0027]
In the potential application pattern shown in the timing chart of FIG. 5, a positive potential application step (T1) that does not generate an electrochemical product, a negative potential application step (T2) that does not generate an electrochemical product, and an electrochemical product The negative potential applying step (T4) to be generated and the positive potential applying step (T6) to generate the electrochemical product are alternately repeated. The applied potential and the application period in each step can be appropriately determined according to circumstances, and the order and frequency are also arbitrary. For example, a positive potential application step (T1) that does not generate an electrochemical product and a negative potential application step (T2) that does not generate an electrochemical product are alternately repeated a certain number of times, and then an electrochemical product is generated. A pattern of applying a negative potential applying step (T4) and a positive potential applying step (T6) for generating an electrochemical product can be created.
In the potential application pattern shown in the timing chart of FIG. 6, a positive potential application step (T1) that does not generate an electrochemical product, a negative potential region that generates an electrochemical product, and / or an amplitude in a negative potential region that does not generate an electrochemical product. The potential application step (T5) and the positive potential application step (T6) for generating an electrochemical product are alternately repeated. The applied potential and the application period in each step can be appropriately determined according to circumstances, and the order and frequency are also arbitrary. The amplitude and change rate of the potential in the amplitude potential application step (T5) in the negative potential region where the electrochemical product is generated / not generated are set in a range that can be output by the control unit 1 depending on the response of the system. can do. For example, a positive potential application step (T1) that does not generate an electrochemical product and an amplitude potential application step (T5) in a negative potential region that does or does not generate an electrochemical product are repeated a certain number of times, and thereafter A pattern of applying a positive potential applying step (T6) for generating an electrochemical product can be created.
[0028]
<Preparation of biofouling prevention material>
Examples 1 to 5 below4The creation procedure of
Example 1
A titanium substrate (t1 × 100 × 100 mm) corresponding to JIS type 2 was degreased and washed with ethyl alcohol, treated in an 8 wt% hydrofluoric acid aqueous solution at 20 ° C. for 2 minutes, and then a 60 wt% sulfuric acid aqueous solution at 120 ° C. For 3 minutes. The titanium base material was taken out of the sulfuric acid solution and cooled rapidly by spraying cold water in a nitrogen atmosphere. Further, it was immersed in a 0.3 wt% hydrofluoric acid solution at 20 ° C. for 2 minutes and then washed with water.
After washing with water, dinitrodiaminoplatinum is dissolved in a sulfuric acid solution to obtain a platinum content of 5 g · dm.^-3In a platinum plating bath adjusted to a pH of about 2, 50 ° C., 3 A · dm on a titanium substrate^-2Was plated for about 50 seconds to deposit platinum. The amount of platinum dispersed and supported is 0.02 g · dm^-2Met. At this time, the platinum coverage of the titanium base material was about 60%.
Subsequently, a butanol solution of chloroiridate and an ethanol solution of tantalum chloride were mixed, and iridium (Ir) 15 g · dm^-3And tantalum (Ta) 25 g · dm^-31 dm with a measuring pipette after adjusting the coating solution containing (metal equivalent)²0.2cm per^ThreeAfter weighing and applying it onto the substrate, it was dried at 50 ° C. for 30 minutes and further baked in the atmosphere at 500 ° C. for 10 minutes. The amount of iridium oxide and tantalum oxide supported is 0.003 g · dm in terms of metal.^-20.005g · dm^-2Met.
Through the above steps, a bioadhesion preventing material carrying a composite of 70 mol% platinum, 11 mol% iridium oxide and 19 mol% tantalum oxide on the surface of the titanium substrate was produced.
[0029]
Example2
In Example 1 above, except that the proportion of the supported material was changed as shown in Table 1, the same procedure as in Example 1 was carried out.2Was made.
[0030]
[Table 1]

[0031]
Example3
After the titanium substrate was acid-treated by the same method as in Example 1, chloroplatinic acid (H₂PtCl₆・ 6H₂O), chloroiridic acid (H₂IrCl₆・ 6H₂O) and tantalum ethoxide (Ta (OC₂H_Five)_Five) Are individually dissolved in butanol and blended so that the composition ratio of the support is 70 mol% of platinum, 11 mol% of iridium oxide, and 19 mol% of tantalum oxide, and platinum (Pt) and iridium (Ir ) And tantalum (Ta) metal concentration is 70 g · dm^-31 dm with a solution pipette²0.4cm per^ThreeAfter weighing and applying it on the titanium substrate, it was dried at room temperature for 30 minutes and then baked in air at 500 ° C. for 10 minutes. The supported amount of platinum, iridium oxide and tantalum oxide is 0.02 g · dm in terms of metal, respectively.^-20.003g · dm^-20.005g · dm^-2Met.
Through the above-described steps, a bioadhesion preventing material in which a composite of 70 mol% platinum, 11 mol% iridium oxide, and 19 mol% tantalum oxide was supported on the surface of the titanium base material was produced.
[0032]
Example4
After acid-treating the titanium substrate in the same manner as in Example 1, platinum was 0.02 g · dm.^-2The dispersion was supported.
Next, iridium (Ir) concentration 7.5 g · dm^-3Which is chloroiridic acid (H₂IrCl₆・ 6H₂1) Butanol solution of O) with a pipette²0.4cm per^ThreeAfter weighing and applying it onto the substrate, it was dried at room temperature for 30 minutes and then baked in air at 500 ° C. for 10 minutes.
Furthermore, tantalum (Ta) concentration of 12.5 g · dm^-31 dm of butanol solution with a measuring pipette²0.4cm per^ThreeAfter weighing and applying it onto the substrate, it was dried at room temperature for 30 minutes and then baked in air at 500 ° C. for 10 minutes. The amount of iridium oxide and tantalum oxide supported is 0.003 g · dm in terms of metal.^-20.005g · dm^-2Met.
Through the above steps, a bioadhesion preventing material carrying a composite of 70 mol% platinum, 11 mol% iridium oxide and 19 mol% tantalum oxide on the surface of the titanium substrate was produced.
[0033]
Comparative Examples 1-5
Example above3Comparative Examples 1 to 5 were produced by changing the ratio of the supported material as shown in Table 1 in the same manner as described above.
[0034]
<Preparation of microorganism suspension>
After primary culture of marine-adherent bacterium Vibrio alginoliticus (ATCC17749) at 30 ° C. in marine broth (Marine broth) 2216 (manufactured by DIFCO Laboratories), 100 μl was collected and cultured in a 25 ml centrifuge tube (15 ml of marine broth). ) At 30 ° C. and 150 rpm for 2 hours. The cultured cells are collected by centrifugation, washed with sterilized seawater, suspended in sterilized seawater, counted with a hematite meter, and 1 × 10⁷A cell suspension having a cell / ml concentration was prepared.
[0035]
<Microbial adhesion to biofouling prevention materials and potential application>
The bioadhesion prevention material was immersed in a suspension stirred at 200 rpm for 90 minutes at room temperature, and the cells were adhered to the surface of the bioadhesion prevention material. It was immersed in sterilized seawater contained in the test tank 6, and various potentials were applied while stirring the sterilized seawater at a stirring speed of 200 rpm. As the potential application condition, each pattern shown in FIGS. Further, the potential of T1 was 0.9 V vs Ag / AgCl and applied for 60 minutes. The potential of T2 was −0.6 V vs Ag / AgCl and applied for 30 minutes. The potential of T3 was −0.3 V to −0.6 V vs. Ag / AgCl, applied for 30 minutes, and the potential was amplified at intervals of 2 minutes. The potential of T4 was −1.4 V vs. Ag / AgCl and applied for 60 minutes. As the potential of T5, −0.3 V to −1.4 V vs Ag / AgCl was applied for 60 minutes, and the potential was amplified at intervals of 2 minutes. The potential of T6 was applied at 1.6 V vs Ag / AgCl for 5 minutes.
[0036]
<Evaluation of sterilization of microorganisms and determination of effects of each process>
The confirmation of the bactericidal effect, the detachment of dead attached microorganisms, and the determination of the cleaning effect were carried out by the double staining method of Propidium Iodide (PI) and 4,6-Diamidino-2-phenylindole (DAPI). PI and DAPI are microorganisms that adhere to nucleic acids of microorganisms due to the difference in the permeability of the cell membrane of microorganisms, and determine the viability of microorganisms by using live cells that exhibit blue fluorescence and dead cells that exhibit red fluorescence. in use. In addition, by comparing the abundance of sterilized red fluorescent microorganisms on the surface of the biological adhesion preventive material, the detachment of scales and organic substances, and the cleaning function were determined.
Microbial staining is performed by washing the bio-adhesion-preventing material to which sterilization is applied with sterilized seawater, and adhering bacterial cells on the bio-adhesion-preventing material with 250 μg / ml aqueous solution of PI and 30 μl each of DAPI 20 μg / ml aqueous solution (adjusted before staining). Drip. Then, irradiate with ultraviolet excitation light, and observe under a fluorescence microscope, live cells that show blue fluorescence, and dead cells that show red fluorescence, adsorb on the bioadhesion-preventing material before potential application The number of dead cells relative to the number of cells was evaluated.
In the determination, ◯ indicates a sterilization rate of 80% or more, Δ indicates a sterilization rate of 20 to 80%, and x indicates a sterilization rate of less than 20%.
[0037]
In the potential application patterns of FIGS. 2 to 6, the sterilizing effect of the microorganisms was determined after completing the T1 step. The determinations of the detachment steps T2 and T3 are as follows: the attached organism amount after applying the potential is a reduction ratio from the time of the T1 step after the sterilization determination, ○ is a reduction rate of 70% or more, Δ is a reduction rate of 30 to 70%, and × is The reduction rate was shown as less than 30%. The determination of the T4, T5, and T6 steps was determined based on the state of each pattern before the T4, T5, and T6 steps and the presence or absence of dead cells after each step.
In order to determine the superiority of the test results, various times were applied for the potential application time and the applied voltage. Therefore, it is desirable to give priority to the test results in consideration of the total results in a short time and at a completely low potential, and the present invention is not limited to this embodiment and application examples.
Hereinafter, in the steps of FIGS.4And the effect is shown based on an application example about Comparative Examples 1-5.
[0038]
Application example 1
As the biological adhesion prevention material 3 of the said apparatus (refer FIG. 1), the said Examples 1-4And the biocide prevention material obtained in Comparative Examples 1 to 5 was used, and the sterilization rate in the T1 step and the cleaning rate in the T6 step when the potential application pattern shown in the timing chart shown in FIG. . The results are shown in Table 2.
In the T1 step, 0.9VvsAg / AgCl was applied for 60 minutes to determine the bactericidal efficiency. In addition, the number of dead cells attached only in the T1 step and the presence or absence of dead cells regarded as organic matter attached after the T6 step was applied at 1.0 V vs Ag / AgCl for 5 minutes, and washed by decomposition. The effect was judged.
[0039]
[Table 2]

[0040]
In the determination of the sterilization effect, ◯ indicates a sterilization rate of 80% or more, Δ indicates a sterilization rate of 20 to 80%, and x indicates a sterilization rate of less than 20%.
The degradation cleaning effect indicates the presence or absence of adherent dead cells, ◯ indicates a cleaning rate of 80% or more, Δ indicates a cleaning rate of 20 to 80%, and X indicates a cleaning rate of less than 20%.
[0041]
Application example 2
As the biological adhesion prevention material 3 of the said apparatus (refer FIG. 1), the said Examples 1-4And the biological attachment prevention material obtained by Comparative Examples 1-5 was used, and the desorption rate in the T2 and T3 process at the time of employ | adopting the electric potential application pattern which the timing chart described in FIG. The results are shown in Table 3.
Since the bactericidal effect showed almost the same bactericidal efficiency as in Application Example 1, 0.9VvsAg / AgCl was applied for 15 minutes in the T1 step, and dead and live bacteria were mixed to prevent adhering organisms. The material was adjusted. Thereafter, the T2 potential in FIG. 3 is applied at −0.6 V vs Ag / AgCl for 30 minutes, and the T3 potential in FIG. 4 is applied at −0.3 V to −0.6 V vs Ag / AgCl for 30 minutes. Amplified at minute intervals. Before and after the T2 step and T3 step at that time, the number of detached microorganisms was compared with the number of attached microorganisms, which is the sum of dead bacteria and viable bacteria, and the reduction ratio was determined to determine the detachment effect.
[0042]
[Table 3]

[0043]
The decrease rate is indicated by O as 70% or more, Δ as 30 to 70%, and X as less than 30%. In addition, the cleaning effect was able to be confirmed with all the biological adhesion prevention materials which implemented T6 process after that, and the cleaning promotion effect by the combination was expectable.
[0044]
Application example 3
As the biological adhesion prevention material 3 of the said apparatus (refer FIG. 1), the said Examples 1-4And the washing | cleaning rate in the T4 and T5 process at the time of employ | adopting the electric potential application pattern which the timing chart described in FIG.5, 6 was employ | adopted as an application pattern using the biological adhesion prevention material obtained by Comparative Examples 1-5. The results are shown in Table 4.
Since the bactericidal effect showed almost the same bactericidal efficiency as Example 1, 0.9VvsAg / AgCl was applied for 15 minutes in the T1 step, and dead and live bacteria were mixed to prevent adhering organisms. The material was adjusted. Thereafter, the T2 potential was -0.6 V vs Ag / AgCl and applied for 30 minutes. Next, the electric setting of T4 was set to -1.4 V vs. Ag / AgCl for 10 minutes. Further, the potential setting of T5 was -0.3V to -1.4VvsAg / AgCl applied for 10 minutes, and the potential was amplified at intervals of 2 minutes. Before and after the steps T4 and T5, the cleaning and reducing effect was determined by the presence or absence of dead cells regarded as attached organic substances.
[0045]
[Table 4]

[0046]
The cleaning rate is indicated by O as 70% or more, Δ as 30 to 70%, and X as less than 30%.
Moreover, when T6 process was implemented after that, almost perfect cleaning effect could be confirmed with all the biological adhesion prevention materials in a short time, and the cleaning promotion effect by combination was expectable.
[0047]
Application example 4 (confirmation of chlorine generation)
Example 14And the biological adhesion prevention material obtained by Comparative Examples 1-5 was immersed in 50 ml of seawater, and 1.0 Vvs. The chlorine concentration in seawater was measured when a potential of Ag / AgCl or higher was applied. The chlorine concentration in seawater to which a potential was applied was measured using a residual chlorine electrode (97 · 70BN; manufactured by Orion Research). 10 ml of seawater after potential application was sampled, and 100 μl each of iodine reagent (manufactured by Orion Research) and acid reagent (manufactured by Orion Research) were added and stirred. After the solution was allowed to stand for 2 minutes, a multimeter (83 MULTITIMER; manufactured by FLUKE) was connected, the potential was measured with a residual chlorine electrode, and the chlorine concentration was determined using a calibration curve from the electrode potential difference from the standard sample. The chlorine measurement limit is 0.2 ppm. A standard sample was prepared by adding 100 μl of each residual chlorine standard solution (manufactured by Orion Research), iodine reagent and acid reagent and stirring for 2 minutes, then adding 9900 μl of distilled water and stirring again.
As a result, there was a difference in the amount of chlorine generated.4And generation | occurrence | production of chlorine was confirmed from all of Comparative Examples 1-5.
[0048]
【The invention's effect】
The biological adhesion preventing material according to the present invention isA biofouling prevention material used in an electrochemical antifouling method using a direct electron transfer reaction between a biofouling prevention material and a living organism,60 to 80 mol% platinum based on metal conversion, 10 to 30 mol% iridium oxide based on metal conversion, and 10 to 30 mol based on metal conversion on a part or all of the surface of the substrate made of titanium or titanium alloy %, It is possible to stably obtain an electrochemical antifouling effect over a long period of time.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an apparatus according to an embodiment.
FIG. 2 is a timing chart of potential control.
FIG. 3 is a timing chart of potential control.
FIG. 4 is a timing chart of potential control.
FIG. 5 is a timing chart of potential control.
FIG. 6 is a timing chart of potential control.
[Explanation of symbols]
1 Control unit
2 Potentiostat
3 Biofouling prevention materials
4 Reference pole
5 Counter electrode
6 Test tank
7 Stir bar
8 Stirrer
9 Positive potential electrolysis product generation potential
10 Negative potential electrolysis product generation potential
T1 Positive potential application process that does not generate electrochemical products
T2 Negative potential application process that does not generate electrochemical products
T3 Amplitude potential application process in the negative potential region where no electrochemical product is generated
T4 Negative potential application process for generating electrochemical products
T5 Amplitude potential application step in the negative potential region that generates / does not generate electrochemical products
T6 Positive potential application process for generating electrochemical products

Claims (1)

A biofouling prevention material used in an electrochemical antifouling method using a direct electron transfer reaction between a biofouling prevention material and a living organism, and a part or all of the surface of the substrate made of titanium or titanium alloy is converted into metal It is characterized in that it carries a composite of 60 to 80 mol% of platinum, 10 to 30 mol% of iridium oxide based on metal, and 10 to 30 mol% of tantalum oxide based on metal. Biofouling prevention material.

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