1 Development status of Marine adhesives
In the early 1990s, several foreign companies saw that China's ship repair industry was still using traditional means to solve wear, corrosion, running, dripping, leakage, seepage, and timely launch a full series of molecular alloy composite materials. Among them, the United States Belzona sodium (Belzona) company launched a super-metal composite material, the United States to Rehakang (Devcon) company launched a series of repair and bonding materials, the United States LocTiTe (LocTiTe) company launched anaerobic sealing, locking, bonding, retaining materials, the United States three M company launched a multi-functional, various types of tape, pressure sensitive adhesive, light solid adhesive, composite adhesive Swiss Castellin (MecaTec) company introduced metal filler, silicate ceramics as filler repair materials. Since 1995, PSI (PSI) company, Hong Kong Gordon Company, Germany Unili Company and a number of Japanese companies have turned their attention to China's shipbuilding market, from Marine main engine system to paint and coating, are permeated with many international high-tech products. While obtaining considerable economic returns, the above foreign companies have brought many new materials and new technologies, which have greatly shortened the distance between China and foreign advanced levels in ship repair methods, ship repair techniques and equipment. All the shipyards have achieved considerable social and economic benefits, and a number of technical personnel who master new materials and new processes.
After 1990, several institutes under the Beijing Bureau of Machinery, scientific research units and production units under the China Shipbuilding Industry Corporation, and several companies under the leadership of the Academy of Armored Forces Engineering launched a full range of polymer composite materials. From 1992 to 1995, the structural, anaerobic, organic and inorganic materials developed and produced by the Guangzhou Institute of Chinese Academy of Sciences, Chengdu Institute, Metal Society, Dalian Second Organic Chemical Plant, Shanghai Xinguang Chemical Plant, Shanghai Tianshan Institute of New Materials Technology were introduced to the ship market. Domestic molecular alloy composite materials with its high quality, low price, variety, series, simple operation and no fire and other characteristics, in the market sales share in just 5 years accounted for 60% of the total. Domestic materials have won the approval of many users at the same time, there are still certain shortcomings, in the information, publicity, service and foreign company products have a certain distance, product stability and storage period are still unsatisfactory, need to be improved.
2 Characteristics and requirements of Marine adhesives and sealants
(1) Marine plane sealing material requirements usually use silicone rubber, silicone and polyester, polyether dry and semi-dry materials, the use temperature is -40 ~ 200℃, pressure ≥10MPa, medium resistance: oil, water, steam, PH value ≤12 various solvents, single component, tube or toothpaste, accumulation thickness is 0.1 ~ 6mm, the material requirements are convenient Operation, no flow, composite surface is easy to disassemble.
(2) Anti-corrosion coating and protective repair materials require the coating material to withstand temperature -40 ~ 100℃, room temperature curing or light curing. Resistant to seawater corrosion, sodium chloride and salt spray corrosion. The coating should be dense without holes, with good adhesion and physical and mechanical strength. Usually, the coating of the hull is docked, and the coating of the equipment in the hull is phenolic resin, inorganic zinc-rich paint, chlorine Juan paint, etc. In the process of using the internal cavity of the Marine main and auxiliary machinery, sodium chloride in sea water is more prominent on the corrosion of castings, and the selection of protective materials should also consider the heat resistance of the coating of -40 ~ 250℃, vibration resistance and stripping resistance of 17MPa. Resistant to corrosion, cavitation, abrasion surface coating, can choose flexible ceramic composite material, this kind of polymer is based on ceramic powder and elastic material as the base material and with curing agent two-component composite material, curing at room temperature, curing process does not shrink, flexible ceramic is thin paste, smooth surface and a certain elasticity. All kinds of main and auxiliary engine cavities, pumps, impellers, propellers, turbine blades, storage tank runner, large diameter pipeline elbow parts can be used. The rubber repair materials for cabin walkway, rubber guardrail wood, hose, rubber pad, oil storage tank and cable are required to be anticorrosive, wear resistant, impact load resistant and room temperature curing. The rubber repair material itself has an insulation strength of 350V/ mil or more, a surface resistance of 2.5×1012Ω, and can be soaked in a variety of chemical media for a long time at 20℃. Due to different uses, rubber repair materials are divided into ordinary bonding type, strong type and brushable type. The hardness of this kind of material is 60 ~ 97(Xiao A), the specific product is 800cm3/Bg, and the temperature resistance is 55 ~ 70℃ in wet state and 60 ~ 92℃ in dry state. However, when bonding all kinds of sealing rings and sealing strips, it is necessary to choose solvent-free cyanoacrylic instant drying adhesive. Due to the different composition of rubber materials, it is necessary to understand the material and working condition requirements when selecting, and it is also possible to make test adhesive samples to ensure the correct selection of materials.
(3) Structural and filling materials selection and requirements of ships in the shipping process, due to failure fatigue, wear, corrosion caused by all kinds of machinery parts, units, pipelines, valves and hull defects, with a variety of polymer composite materials repair, overall should be regarded as emergency measures to maintain the normal navigation of the ship. However, often some product production and sales personnel introduce bonding and repair materials into replacement products without defects, and their purpose is to find a basis for profiteering. Structural materials for dimensional repair, various types of defects, machine parts fracture and local conditions emergency strengthening to achieve indisputable effect, because the vast majority of such materials are epoxy composite materials, easy to operate, long period of validity, room temperature curing, the 1950s foreign shipping industry, almost every ocean ship is regarded as ocean sailing products. Since the main body of epoxy materials is various types of additives and epoxy resins, such products have a wide range of applications and different functions, such as: adding various types of black and colored powder, different viscosity, different curing agents, and the performance of the finished product is very different. Such as compressive strength 42 ~ 120MPa, tensile strength 30 ~ 80MPa, shear strength 0.5 ~ 24MPa, hardness Shore D40 ~ 120, the use of temperature 86 ~ 250℃.

        The storage period of foreign products at room temperature can reach 5 years, and domestic products are generally more than 2 years. Adjusting the type of curing agent The product can also be made into fast solid type and slow dry type, curing time (at the ambient temperature of 25℃) from 3 ~ 5min to 30 ~ 45min. Usually fast solid materials have high hardness (Xiao D70 ~ 92), poor fatigue resistance and impact resistance. The normal temperature curing type has higher comprehensive physical parameters, stable technical indicators, long anti-aging time and hardness of Shore D70 ~ 98. With the improvement of the level of science and technology, the high temperature epoxy and temperature mixed epoxy (high temperature 240℃, high temperature 500℃) materials launched on the market in the past two years can play a significant role in the repair of the main engine cylinder head, Marine boilers, heavy oil tank heating pipes, supercharger. Due to its many properties, polymer composites are increasingly used by ship repair engineers and technicians. However, in the use of structural repair, for the occasion of vibration and impact load, as long as conditions are available, it is recommended to use mechanical strengthening method and composite repair material applied at the same time, the effect is better, and often achieve twice the result with half the effort.