Research progress on silicone low surface energy marine antifouling coatings
Qin Ruirui, Hu Shengxiang, Gong Xiangyi
(Zhengzhou Zhongyuan Applied Technology Research and Development Co., Ltd., Zhengzhou 450007)
Abstract: The antifouling mechanism of silicone marine antifouling coatings is summarized. The research progress of silicone marine antifouling coatings and acrylic, epoxy and polyurethane modified silicone marine antifouling coatings is reviewed. The development direction of antifouling coatings.
Keywords: antifouling, coating, ocean, silicone, modification, low surface energy, silicone oil
CLC number: TQ324.2+1 Document code: Adoi: 10.11941/j.issn.1009-4369.2015.01.016
The marine antifouling paint is applied to the surface of the underwater part of the hull. Its function is to reduce the pollution of the hull surface by marine organisms and keep the hull smooth to reduce fuel consumption and extend the service life of the ship. The anti-fouling coating containing organic tin insecticide appeared in the middle of the 20th century has good anti-fouling effect, but it has been completely banned in 2008 due to serious damage to the marine environment [1]. Although other insecticides (such as copper oxide and joint insecticides) can be used instead of organotin pesticides to make antifouling coatings, such antifouling coatings are as harmful to the environment as organotin coatings. Therefore, the development of new antifouling coatings with low surface energy and complete environmental friendliness is of great significance for the safety of marine transportation, especially the protection of the marine environment. It has become a hot spot in the research of marine antifouling coatings at home and abroad in recent years [2].
At present, low surface energy antifouling coatings are mainly based on silicone polymers or fluoropolymers [3]. In fact, due to the high price and difficult preparation of fluoropolymers, commercial products are still rare; marine antifouling coatings based on silicone polymers have become hot spots for internationally renowned paint manufacturers to compete in R&D and production [4] ].
1 Antifouling mechanism of silicone marine antifouling coating
RFBrady has conducted in-depth research on the antifouling principle of coatings. It is found that the surface energy of the coating is the main factor affecting the adhesion of the organism. When the surface energy is between 22 and 25 mJ/m2, the amount of bio-adhesion is the least; and the surface energy has a certain relationship with the elastic modulus. The elastic modulus of the coating is more The lower the flexibility, the more cracks or cracks in the hull or primer are less likely to crack, and the more the fouling material tends to fall off in a peeling manner [5]. This shedding method is one of the three modes (peeling, plane shearing, and non-planar shearing) in which marine fouling is removed from the surface of the coating [6].
In addition, the molecular structure of the polymer, the thickness of the coating film, the polarity, the molecular fluidity and the like also have a certain influence on the antifouling effect. The silicone polymer has low surface energy (21.2mJ/m2) and low modulus of elasticity (0.002GPa), which makes the silicone marine antifouling coating have strong self-cleaning ability, and it is difficult for marine fouling to adhere to it; even It can be easily removed by flushing or decontaminating equipment on the surface by water flow. If vinyl, hydroxyl or other reactive groups are introduced into the silicone polymer molecule, coupling agents, auxiliaries, fillers, etc., can also enhance the strength of the coating and the adhesion to the substrate. .
At present, silicone marine antifouling coatings are mainly classified into coatings based on silicone polymers and coatings based on organic resin modified silicone polymers. Introduced separately below.
2 silicone marine antifouling coating
Pure silicone marine antifouling paint is applied to the surface of the hull. During the running of the ship, silicone oil or other additives slowly infiltrate from the coating body to the surface of the coating, so that the surface is smooth and oily, and the fouling is attached to it. Or easy to remove under the action of decontamination equipment, so as to achieve anti-fouling and easy cleaning.
In 1972 WJ Mueller won the first patent for silicone marine antifouling coatings. The coating is based on silicone rubber and is prepared with other additives [7]. Subsequently, several related patents appeared [8-10]. Early anti-fouling effects of such coatings on marine life were not as good as conventional coatings. Later, there were several reports on silicone marine antifouling coatings [11]. Although these coatings have certain antifouling effects, they have poor workability, long curing time, poor recoatability, and weak adhesion to the hull, which cannot be applied in practice, but pointed out a new research for silicone marine antifouling coatings. direction.
After the 1990s, silicone marine antifouling coatings developed rapidly. LWRoy uses a self-made silicone resin with vinyl and hydrogen as a base material, together with some additives, to produce a silicone marine antifouling coating. It was applied to the hull coated with silicate primer. After 6 months of solid sea plate, it showed good antifouling effect and the coating also maintained good integrity [12].
Y.Yonehara et al. use a series of self-made vinyl- or/and hydroxyl-terminated silicone polymers with different structures as base materials, and use different proportions of silicone oil as additives to add solvents and fillers. Marine antifouling coating for insecticides. It is carried out with a conventional vinyl chloride resin antifouling coating (the insecticides used are: triphenyltin fluoride and red Fe2O3; Cu2O, red Fe2O3 and BaO; triphenyltin fluoride, Cu2O and red Fe2O3). Month of real sea hanging board comparison experiment. The results show that the surface tension of silicone marine antifouling coatings is significantly lower than that of traditional marine antifouling coatings, and the antifouling effect is better than traditional antifouling coatings [13]. K.Masato et al. synthesized hydroxyl-terminated polyorganosiloxanes with different viscosities, adding vinyl or keto-silane coupling agents, boric acid organic catalysts, and silicone oils containing different groups (methyl, phenyl, etc.). Get silicone marine antifouling paint. After 4 months of coating the solid sea plate, the surface is almost free of marine organisms; on the surface of the silicone-free coating, there are many sludges, shellfish and vegetation [14]. S. Takafumi synthesizes different molar masses (250-100000g/mol) of silicone oil with polyether chain, long-chain alkyl group and/or aryl group, and is added to condensed room temperature vulcanization (RTV) silicone resin in different proportions. , made of antifouling paint for underwater use. In use, the surface tension of the coating is lowered by the slow oozing of the silicone oil to the surface, thereby exerting an antifouling effect. Compared with the traditional vinyl chloride butyl isobutyl ether antifouling coating, the antifouling effect of the coating can reach more than 2 years, while the traditional antifouling coating has a different degree of pollution after using for up to 1 year [15]. . J. Stein of General Electric Company of the United States synthesizes silico-hydroxy, carbonyl, dialkoxy and trialkoxy-terminated polyorganosiloxanes, and adds filler silica (SiO2) or calcium carbonate with catalyst and even A condensing RTV marine antifouling coating is prepared by using an auxiliary agent such as a crosslinking agent. The real sea hanging plate experiment confirmed that 91% to 99% of the surface of the coating after 12 months of underwater was not contaminated by marine organisms [16-18]. T.Sakamoto of Shin-Etsu Corporation of Japan is based on a condensation-type RTV silicone resin containing at least two silanol groups or other hydrolyzable groups as a base material, an ionic liquid as an auxiliary agent, and a silane having a silanol group or other hydrolyzable group. , made of underwater antifouling paint. The solid sea hanging plate experiment confirmed that the coating still has good antifouling performance under water for more than 12 months [19-20]. Wang Ke et al. synthesized dimethyl silicone oil and dimethyl diphenyl silicone oil and added them to the silicone marine antifouling coating. The morphology and SEM photographs of the silicone oil on the surface of the coating explained the antifouling of the silicone oil on the coating. The impact of performance. The solid sea hanging board confirmed that the antifouling performance of the antifouling coating added with silicone oil, especially phenyl silicone oil, is greatly improved, and even if the attached marine organism adheres, it can easily fall off without affecting the stability of the coating in seawater [ twenty one].
Since silicone-based antifouling coatings based on pure silicone polymers are easy to prepare, commercial products have been formed, such as Hempasil 77500 series from Hempel, Denmark, International Intersleek from Akzonobe, Netherlands, Captain Biox from Kansai, Japan, and Jotun from Norway. Sealion et al. Although these products have excellent performance, they have a slightly lower antifouling effect than conventional antifouling coatings, and are more expensive.
The antifouling effect of the pure silicone marine antifouling coating is partially penetrated from the coating body to the surface by silicone oil or other additives, so that the fouling material adhering to the oil surface is easily detached, thereby preventing the fouling effect. Therefore, the disadvantages of such coatings are also obvious. The outstanding problem is that silicone oil or other additives are generally released within 2 to 3 years, so that the coating loses antifouling properties; and the recoatability of such coatings is also poor, and it is difficult to Repair it. Therefore, there are still many problems in silicone marine antifouling coatings to be solved.
3 organic resin modified silicone marine antifouling coating
In order to overcome the defects of pure silicone marine antifouling coating (such as insufficient bonding strength with hull, poor recoatability, long-term use cracking, short anti-fouling period, etc.), organic resin modified silicone polymer can be used as antifouling coating. Base material. The organic resin-modified silicone polymer is a reactive group (such as a hydroxyl group, a carboxyl group, an isocyanate group, etc.) on an epoxy resin, an acrylic resin, a urethane resin, a phenol resin or the like, and a reactive group on the silicone polymer (eg, The hydroxyl group, methoxy group, ethoxy group, etc. are reacted to improve the performance of certain aspects of the silicone polymer, and at the same time have the low surface energy characteristics of the silicone polymer.
3.1 Acrylic resin modified silicone marine antifouling coating
Acrylic resin has excellent acid and alkali resistance and corrosion resistance, and can be combined with silicone to form weatherproof, gloss and color retention, anti-powdering and antifouling coatings with excellent adhesion to inorganic substrates. The modification method has simple physical blending and chemical modification with better modification effect. Chemical modification is further divided into a polycondensation method, a radical polymerization method, and a hydrosilylation method.
The marine antifouling coating prepared by MLChen et al. based on acrylic modified silicone and nano-SiO2 as filler has lower surface energy and elastic modulus, and studied SiO2 content and surface energy () and elastic modulus (E The relationship of one-half of the square [ie (E) 1/2]. The solid sea hanging board found that the higher the SiO2 content, the lower the (E) 1/2 value and the better the antifouling effect [22]. Zhang Shanzhi et al. modified the acrylic resin and epoxy resin with polyorganosiloxane to form an antifouling coating. The study found that the higher the silicone content, the greater the contact angle between water and coating; the 6-month solid sea hanging board experiment found that all the hanging boards were covered with marine plants, and some of the test plates had a small amount of sea otters at the edges, but High pressure water rinses are easily removed and the coating is virtually unbroken [23].
3.2 epoxy resin modified silicone marine antifouling coating
Epoxy resin has good chemical resistance, organic solvent resistance, electrical insulation properties and low curing shrinkage, good adhesion to substrates, and easy processing; silicone and epoxy resin combined It reduces the surface energy of the composite material and has certain elasticity, which is an important direction for the modification of marine antifouling coatings.
S. AKumar. et al. grafted epoxy resin onto a silicone polymer to make a marine antifouling coating. The coating has improved impact resistance, thermal stability, water resistance, corrosion resistance and dielectric properties, reduced hardness, improved antifouling properties and service life [24].
Tian Jun et al. used silicone resin and epoxy resin as the base material, polytetrafluoroethylene and paraffin oil as functional fillers, and added pigment and curing agent to produce RTV anti-marine biofouling coating. The coating obtained therefrom has good adhesion to the rust preventive primer, has strong antifouling property and is non-toxic to the living [25].
3.3 polyurethane modified silicone marine antifouling coating
Polyurethane has good wear resistance, strong adhesion, acid, alkali, oil and chemicals, and a wide temperature range. The modification of the silicone polymer with polyurethane can make up for the shortcomings of poor adhesion of the silicone polymer to the substrate, while retaining the advantages of low surface energy of the silicone polymer.
JDAdkins et al. developed a two-coat system with a silicone-coated polybutadiene or polyurethane (physical mixing) and a topcoat low surface energy silicone. Since the silicone resin can be grafted with polybutadiene or polyurethane to obtain a double coating, the coating adheres well to the hull. Experiments have shown that this coating has a small amount of fouling after being immersed in seawater for 24 months, but it is easy to clean with equipment [26].
In addition to the above several organic resin-modified silicone coatings, there are also modified silicone coatings such as phenolic resins and polyethers. Compared with pure silicone marine antifouling coatings, the mechanical properties of organic resin modified silicone coatings and the adhesion to the hull are improved; however, this modification can also cause new problems, such as surface treatment of substrates. Complex, harsh construction conditions, and difficult to repair.
4 outlook
As society pays more and more attention to environmental protection, marine antifouling coatings will gradually turn to non-toxic and environmentally friendly. The low surface energy antifouling coating based on silicone is an environmentally friendly marine antifouling coating; however, the current problems of the coating are also urgently to be solved, such as low mechanical strength, poor adhesion to the hull, and difficulty in repairing. The construction is difficult, and the coating will crack due to the release of the silicone oil. With the continuous improvement of technology, modified silicone marine antifouling coatings will make up for these defects and become the main development direction of such coatings.
(Finish)Cutting mode: Laser cutting
Suit material: carbon steel, alloy steel, galvanized plate, stainless steel, copper plate, aluminium plate, steel tube, copper pipe, aluminium pipe etc. sheet tube stock.
1.Product describe
Fast cutting speed, high working efficiency and high stability, it is a high-tech equipment that set one of fiber laser technology, CNC technology and high-tech equipment.
2. Product features
Imported with original packaging servo motor and reducer, bilateral drive, high operating speed and high precision.
Can remote operation, convenient and efficient, save labor.
Imported cutting head, optical glass, focusing is convenient and cutting perfect.
Fiber transmission, no need to adjusted the optical circuits, focal spot is more smaller.
Adopted auto lubrication system, auto dual-temperature control system, convenient and efficient.
High precision grinding guide rail, gear and rack, precision class up to ±0.02mm.
Tube Sheet Integrated Cutting Machine
Pipe Cutting Machine,Cnc Pipe Cutting Machine,Plate Laser Cutting Machine,Tube Sheet Integrated Cnc Cutting Machine
Buluoer Intelligent Technology Co., Ltd. , https://www.buluoercuttingmachine.com