Japan Nippon Paint Development Antifouling Bottom Coating

It is said that the speed of large-scale tuna in the ocean can reach 80km/h. The shape of the tuna does belong to the streamlined shape of the fast speed, but in addition, there should be other flaws that reduce the frictional resistance of the water. The advent of a product is derived from this idea. That is the anti-fouling bottom coating "LF-Sea" developed by Nippon Marine Coatings (Headquarters: Kobe City).
The secret is that the tuna on the surface of the mucous membrane that keeps moving at high speed has no scales, and its body surface is covered with a sticky and smooth mucous membrane. Although the details are still unknown, there is a perception that under the action of this mucosa, the frictional resistance of the boundary layer in the turbulent state will be weakened. In fact, studies have shown that after adding a very small amount of polymer to the liquid, the turbulent liquid frictional resistance will be weakened (Toms effect), which may be the same phenomenon on the body surface of the tuna.
“Because I am engaged in the development of ship bottom coatings, I often think about the inspiration for developing products from fish and marine life.” Shan Shengzhi, executive director of Nippon Marine Coatings Technology Division, has set his sights on tuna. When the ship is sailing, the surface friction of the bottom of the ship that contacts the sea water accounts for 50-80% of the total resistance. According to Shan Sheng's idea, if the ship can achieve liquid-liquid contact between the mucous membrane and seawater, instead of solid (the bottom of the ship) in direct contact with seawater, it should be able to reduce the resistance.
The red part is coated with the bottom coating (a). From the sprayed sample, it can be seen that there is unevenness on the surface (b).
To this end, Shansheng has adopted a method of incorporating a highly hydrophilic and viscous hydrogel into the bottom coating, thereby reducing friction with water. The bridged polymer in the hydrogel can form a three-dimensional mesh early enough to store water in the mesh. In daily life, kelp soup and agar also fall into this category.
In this way, the LF-Sea, which does not impair the basic purpose of the bottom coating to prevent the attachment of aquatic organisms such as barnacles, and which can weaken the frictional resistance of seawater, has emerged. It has been confirmed that the ferry using this coating can save about 3.4% of fuel consumption (Figure 2). Although only 3.4% of the area can be converted into fuel costs, it can save about 10 million to 20 million yen. Therefore, since it was put into production in 2008, it has been adopted by more than 600 vessels.