【発明の詳細な説明】[Detailed description of the invention]
本発明は海水と接触する構築物の表面に海棲生
物が付着することを防止する方法に関する。
近年、沿岸海域における海洋開発の進展に伴つ
て、種々の目的で大型の海洋構築物、その付属構
築物、その他類似の海水と接触する構築物の建
設、設置が増加している。そしてこのような海水
と接触する構築物は海水による腐食のトラブルに
加えて、該構築物の海水と接触する部分またはそ
の付近に付着性海棲生物が付着生育する汚染のト
ラブルがあり、その効果的な防止方法の開発が望
まれている。
例えば、沿岸における各種の施設や工場、発電
所などで、冷却用その他各種の利用目的で、海水
を利用する際に海水の採取管、排出管、ポンプ
類、その他の水路や溝などの沿岸の構築物に生物
付着汚染を生ずる付着性海棲生物が、付着生育
し、甚だしい場合には数十cmの程度にも付着生育
して水路有効面積の減少、流れ抵抗の増大、ポン
プ類や浮遊固型物除去用スクリーンの目詰り、そ
の他の被害をうける。
その他、航路浮標、灯浮標、けい留ブイ、浮桟
橋、浮防波堤、浮ドツクなどの港湾内施設構築
物、養・蓄魚介類用イケス、漁業用定置網、その
他類似の水産用施設、構築物などの海水と接触す
る構築物は付着性海棲生物がこれらの構築物へ付
着生育することによつて、構築物基材の腐食促
進、重量増加に伴う不都合な沈下発生やバランス
の不安定化発生などの被害を受ける。
このような海水と接触する構築物に対する付着
性海棲生物による被害を防止する目的で、例えば
次亜塩素酸ナトリウムや塩素水などを注入するこ
とが行なわれてきたが、環境汚染を伴なうことが
避けられないため、現在では防汚剤を含有する塗
料組成物で塗装処理し、該組成物から有効濃度の
防汚剤の溶出を生じさせて、付着性海棲生物を死
滅あるいは付着を忌避させる方法が一般的であ
る。
例えば防汚性塗料組成物として利用される船底
塗料には防汚剤として亜酸化銅、テトラメチルチ
ウラムジサルフアイド、ジンクジメチルジチオカ
ーバメイト、トリフエニル錫ハイドロオキサイ
ド、トリフエニル錫アセテート、トリフエニル錫
クロライド、およびそれらの誘導体が利用されて
いる。しかしながらこのような防汚剤はその毒性
の点に問題点があり、上記例示の如き有機錫化合
物その他の防汚剤はマウス又はラツトによる経口
投与のLD50値がいずれも1000mg／Kg以下とかな
り高い毒性を示し、他の生物に対する悪影響が無
視できず安全性の点で疑問が残り、２次的な海洋
汚染をひき起す恐れを伴う。
更に付着汚染を生ずる付着性海棲生物を死滅ま
たは付着を忌避させるのに充分な有効濃度の防止
剤の溶出によつて付着汚染を防止するという防止
機構から当然のことながら上記２次的な汚染の問
題が回避し難い欠点に加えて該防汚剤の溶出コン
トロールが実際上困難であるという技術的な課
題、溶出に伴つて防汚剤の含有量が減少するため
付着汚染防止効果の持続性にも本質的な欠陥があ
る。
最近ではこのような防汚剤を用いない新しいタ
イプの防汚塗料が幾つか開発されている。例えば
パラフインワツクスコーテイグ材や含シリコーン
樹脂塗料などが挙げられる。これらはいずれも塗
膜表面の臨界自由エネルギーを25〜30dyne／cm2
に保ち、海水との接触角を大きくするため、表面
化学的に海棲生物が付着しにくいという特徴を持
つ。これらは有毒性の防汚剤を配合していないた
め、急性毒性はさほど高くないが、海水による加
水分解を受けやすく、塗膜の劣化に基くCODの
増加が問題になることは明らかである。また海水
中では化学的に安定でないために防汚効果の長期
持続性は期待できない。更に塗装工程および塗装
前処理がはん雑であることからコスト的にも高く
つくことが予想される。
本発明者らは長年の研究により、これら従来の
防汚塗料とは全く異なる防汚機構を持つ防汚方法
を開発した。
すなわち本発明は、海水と接触する構築物の塗
装面に球状物質を散布付着せしめることを特徴と
する海棲生物付着防止方法である。
上記構築物としては、すでに例示したような港
湾内施設構築物、レジヤー用構築物、水産用施設
構築物、沿岸構築物等を挙げることができる。こ
のような海水に接触する構築物の接触部分を構成
する基材の例としては、たとえばコンクリート、
石材、各種スレート、ケイ酸カルシウム等の板、
ブロツク、柱や管等のごとき無機材料基材、アル
ミニウム、鉄、ステンレス等の金属板、柱、管等
のごとき金属無機材料基材等を挙げることができ
る。
本発明に使用される球状物質の材質としてはガ
ラスビーズ、セラミツク、金属、鉱物などの無機
材料、プラスチツク、ゴム等の有機材料が例示さ
れ中空体であつても差支えない。
またその形態は球状であれば特に制限はないが
表面が平滑なものが好ましく、平均粒径は望まし
くは20〜1000μm、特に望ましくは50〜500μm程
度である。平均粒径20μm未満の場合は塗装表面
を粗面化しうる効果が少なく、また1000μmを越
えると球状粒子間の空隙が大で海棲生物付着防止
効果が減少する。
またこれらの球状物質を分散付着せしめる塗料
としては耐海水性、基材および球状物質との密着
性、さらにコンクリート等吸水性の大きな基材に
塗布する場合は、ある程度の湿潤面に対する密着
性が要求される。このような塗料としてはウレタ
ン樹脂塗料、エポキシ樹脂塗料、塩化ゴム系塗料
などの合成樹脂塗料、およびポルトランドセメン
ト、アルミナセメント、アルカリシリケート、ア
ルキルシリケート等を用いた無機塗料等が挙げら
れる。基材が鋼材の場合には防食の点から合成樹
脂系またはアルキルシリケート系の塗料が優れ、
コンクリート系の場合は無機系の塗料が好まし
い。ガラスビーズ、セラミツク、鉱物などの無機
材料の球状物質と合成樹脂塗料とは塗着性が悪い
ため、球状物質の表面をあらかじめシラン系、チ
タネート系等のカツプリング剤で処理しておく必
要がある。
本発明を施工するには基材に塗料をコーテイン
グして未乾燥、未硬化の間に球状物質を散布し、
常温硬化あるいは加熱硬化させればよい。
このような施工は海水と接触する構築体の表面
に直接行つてもよく、またあらかじめ施工を行つ
たパネル等を取つけてその表面を海水と接触する
ようにしてもよい。
本発明の如く球状物質を塗装面に付着せしめた
場合、海棲生物の付着を防止しうる理由について
は明らかでない。しかしこのような球状物質によ
り海水と接触する構築物表面を粗面化することに
より、通常の海水の流速において該表面の摩擦速
度が大きく境膜層が薄くなり、表面近くでの流速
が大きくなり、海棲生物の該構築物表面への付着
力を上まわる海水の流れによるせん断力が得られ
る為、海棲生物付着防止効果があるものと考えら
れる。
本発明の効果は海水の流速が0.5m／秒以上で
ある場合に著しく特に0.7m／秒以上であれば顕
著である。
本発明を従来法と比較した場合の効果を列挙す
ると次のごとくである。
防汚機構が化学的なものだけでなく物理的要
因が大きいため効果の経時的減退がない。
安全性が高く、海洋汚染のおそれがない。
使用素材は目的用途に応じて広く選択でき
る。
以下実施例、比較例により本発明の効果を説明
する。
実施例１〜７、比較例１〜４
長さ200mm、管径200mmの鋼管、およびヒユーム
管の内壁に次表に示す各種塗料をコーテイング
し、塗料が乾燥しない間に球状物質を噴霧して塗
膜表面に付着させる。塗膜形成後３日間20℃、60
％RH下で養生後、平均流速1m／秒の海水取水
路（暗渠）に流れの方向に平行に設置し（深さ
2m）、半年、１年、２年後に引き上げ、内壁に付
着している海棲生物の総重量を生物別に観察す
る。比較例として無塗装のヒユーム管、タールエ
ポキシ塗料、エポキシ樹脂塗料、セメント系塗料
をコーテイングした鋼管またはヒユーム管も同時
に設置した。
結果を第１表に示す。
The present invention relates to a method for preventing marine organisms from adhering to surfaces of structures that come into contact with seawater. In recent years, with the progress of marine development in coastal waters, the construction and installation of large marine structures, their auxiliary structures, and other similar structures that come into contact with seawater have increased for various purposes. In addition to the problem of corrosion caused by seawater, such structures that come into contact with seawater also have the problem of contamination due to the growth of adherent marine organisms on or near the parts of the structure that come into contact with seawater. Development of prevention methods is desired. For example, when seawater is used for cooling and other purposes in various coastal facilities, factories, power plants, etc., seawater collection pipes, discharge pipes, pumps, and other coastal channels such as waterways and ditches are used. Adhesive marine organisms that cause biofouling contamination of structures grow on structures, and in extreme cases, they grow on several tens of centimeters, reducing the effective area of waterways, increasing flow resistance, and damaging pumps and floating solids. The material removal screen may become clogged and other damage may occur. In addition, seawater facilities such as channel buoys, light buoys, tethering buoys, floating jetties, floating breakwaters, floating docks, etc., iketsu for fish farming and stocking fishery products, fixed nets for fishing, and other similar fisheries facilities and structures. Structures that come into contact with the structure are subject to damage due to the growth of adherent marine organisms on these structures, such as acceleration of corrosion of the structure base material, inconvenient sinking due to increased weight, and destabilization of the balance. . In order to prevent damage caused by adherent marine organisms to structures that come into contact with seawater, for example, injection of sodium hypochlorite or chlorinated water has been carried out, but this approach is accompanied by environmental pollution. Since this is unavoidable, at present, coating treatment is performed with a paint composition containing an antifouling agent, and an effective concentration of the antifouling agent is eluted from the composition to kill the adherent marine organisms or prevent their adhesion. A common method is to For example, ship bottom paints used as antifouling paint compositions contain antifouling agents such as cuprous oxide, tetramethylthiuram disulfide, zinc dimethyldithiocarbamate, triphenyltin hydroxide, triphenyltin acetate, triphenyltin chloride, and the like. derivatives are used. However, such antifouling agents have a problem with their toxicity, and the LD 50 value of the organotin compounds and other antifouling agents as exemplified above is less than 1000 mg/Kg when administered orally to mice or rats. It exhibits high toxicity, has a non-negligible adverse effect on other living things, raises questions about its safety, and carries the risk of causing secondary marine pollution. Furthermore, due to the prevention mechanism, which prevents adherent contamination by elution of an inhibitor with an effective concentration sufficient to kill or repel adherent marine organisms that cause adherent contamination, the above-mentioned secondary contamination is naturally caused. In addition to the disadvantages that are difficult to avoid, there are technical issues such as the fact that it is practically difficult to control the elution of the antifouling agent, and the sustainability of the antifouling effect because the content of the antifouling agent decreases as it elutes. also has fundamental flaws. Recently, several new types of antifouling paints that do not use such antifouling agents have been developed. Examples include paraffin wax coating materials and silicone-containing resin paints. All of these have a critical free energy of 25 to 30 dyne/cm 2 on the surface of the coating film.
The surface chemistry of the surface makes it difficult for marine organisms to adhere to it, as it maintains a high contact angle with seawater. Since these do not contain toxic antifouling agents, their acute toxicity is not very high, but they are susceptible to hydrolysis by seawater, and it is clear that an increase in COD due to paint film deterioration is a problem. Furthermore, since it is not chemically stable in seawater, it cannot be expected that its antifouling effect will last long. Furthermore, since the painting process and pre-painting treatment are complicated, it is expected that the cost will be high. Through many years of research, the present inventors have developed an antifouling method that has an antifouling mechanism completely different from those of these conventional antifouling paints. That is, the present invention is a method for preventing adhesion of marine organisms, which is characterized by spraying and adhering spherical substances to the painted surface of a structure that comes into contact with seawater. Examples of the above-mentioned structures include the above-mentioned port facility structures, leisure structures, fisheries facility structures, coastal structures, and the like. Examples of base materials that make up the contact parts of structures that come into contact with seawater include concrete,
Stone, various types of slate, boards made of calcium silicate, etc.
Examples include inorganic material base materials such as blocks, pillars, pipes, etc., metal plates such as aluminum, iron, stainless steel, etc., metal inorganic material base materials such as pillars, pipes, etc. Examples of the material for the spherical substance used in the present invention include inorganic materials such as glass beads, ceramics, metals, and minerals, and organic materials such as plastic and rubber, and hollow bodies are also acceptable. The shape is not particularly limited as long as it is spherical, but it is preferable to have a smooth surface, and the average particle size is preferably about 20 to 1000 μm, particularly preferably about 50 to 500 μm. When the average particle diameter is less than 20 μm, the effect of roughening the painted surface is small, and when it exceeds 1000 μm, the voids between the spherical particles are large, reducing the effect of preventing marine organisms from attaching. In addition, paints for dispersing and adhering these spherical substances must have seawater resistance, adhesion to the base material and the spherical substances, and, when applied to highly water-absorbing substrates such as concrete, a certain degree of adhesion to wet surfaces. be done. Examples of such paints include synthetic resin paints such as urethane resin paints, epoxy resin paints, and chlorinated rubber paints, and inorganic paints using portland cement, alumina cement, alkali silicate, alkyl silicate, and the like. When the base material is steel, synthetic resin-based or alkyl silicate-based paints are superior in terms of corrosion protection.
In the case of concrete-based paints, inorganic paints are preferred. Since spherical substances made of inorganic materials such as glass beads, ceramics, and minerals have poor adhesion to synthetic resin paints, it is necessary to treat the surface of the spherical substances in advance with a coupling agent such as silane or titanate. To apply the present invention, coat the base material with paint and sprinkle spherical substances while it is not dry or cured.
It may be cured at room temperature or by heating. Such construction may be performed directly on the surface of the structure that comes into contact with seawater, or a panel or the like that has been previously worked may be attached so that the surface comes into contact with seawater. It is not clear why adhesion of marine organisms can be prevented when spherical substances are attached to a painted surface as in the present invention. However, by roughening the surface of the structure that comes into contact with seawater using such spherical materials, the frictional velocity of the surface increases at the normal seawater flow rate, and the membrane layer becomes thinner, increasing the flow velocity near the surface. Since the shearing force generated by the seawater flow exceeds the adhesion force of marine organisms to the surface of the structure, it is thought to have the effect of preventing marine organisms from adhering to the structure. The effects of the present invention are remarkable when the flow velocity of seawater is 0.5 m/sec or more, particularly when it is 0.7 m/sec or more. The effects of the present invention when compared with conventional methods are listed below. Since the antifouling mechanism is based not only on chemical factors but also on physical factors, the effectiveness does not decrease over time. It is highly safe and there is no risk of marine pollution. The materials used can be selected from a wide range depending on the intended use. The effects of the present invention will be explained below using Examples and Comparative Examples. Examples 1 to 7, Comparative Examples 1 to 4 The inner wall of a steel pipe with a length of 200 mm and a pipe diameter of 200 mm, and a humid pipe were coated with the various paints shown in the table below, and while the paint was still waiting for it to dry, a spherical substance was sprayed. Adhere to the membrane surface. 20℃, 60 for 3 days after coating film formation
After curing under %RH, it was installed parallel to the flow direction (depth
2 m), and after six months, one year, and two years, the total weight of each marine creature attached to the inner wall was observed. As comparative examples, unpainted hume pipes, steel pipes or hume pipes coated with tar epoxy paint, epoxy resin paint, or cement-based paint were also installed at the same time. The results are shown in Table 1.
【表】【table】
【表】
実施例８、比較例５
東京湾内火力発電所の冷却水取水路（暗渠）壁
面に約10m2の試験施工を行つた。塗装仕様はアル
カリシリケート系塗膜に平均粒径約120μmのガラ
スビーズ約120ｇ／m2を付着させたものである。
１年間経過後の海棲生物の付着量を定量し、同水
路の無塗装コンクリート面の付着量と比較した。[Table] Example 8, Comparative Example 5 Approximately 10 m 2 of test construction was carried out on the wall of a cooling water intake channel (culvert) at a thermal power plant in Tokyo Bay. The coating specifications are an alkali silicate coating coated with approximately 120 g/m 2 of glass beads with an average particle size of approximately 120 μm.
The amount of marine organisms attached after one year was quantified and compared with the amount attached to the unpainted concrete surface of the same waterway.
【表】【table】
【表】
ムラサキイガイ以外の生物はきわめて少く対象
にならない。[Table] Organisms other than mussels are extremely rare and cannot be targeted.