Jiang Deqiang Ma Xiangsheng Ding Wei (Lanzhou Zhiben Chemical Technology Co., Ltd., Lanzhou 730000) is composed of an amine zinc-rich primer and an epoxy resin polyamide mica iron oxide. The outer coating of the cylinder is made of epoxy resin polyamide zinc-rich primer. , epoxy resin polyamide mica iron oxide paint and acrylic aliphatic polyurethane cool topcoat. The anti-corrosion coating of the coating system can be cured at room temperature and has a thickness of 275! m, anti-corrosion life can reach 20 years, its anti-corrosion effect, impact resistance and weather resistance are good. The article also discusses the problems and solutions that are easy to occur during the coating process.
Modern Coatings and Coatings 2002. 1 Proverbs Environmental protection is becoming more and more important in China today. Wind power generation has the characteristics of low one-time investment, low operating cost and no pollution, and has become a very promising project. During the manufacture and use of wind turbines, the anti-corrosion work of the tower is an important part, because it needs to run for several decades, and its height is more than 30m. Maintenance is difficult, so it takes a long time to paint. Corrosion protection life.
The wind turbines painted in this project are made of several cylindrical steel rings welded with carbon steel. The dimensions and coating requirements are listed in Table 1.
2 Preparation of coatings 2.1 Raw materials Domestic raw materials: epoxy resin, polyamide curing agent, acrylic resin, zinc powder, micaceous iron oxide, filler, organic solvent, etc.; imported raw materials: titanium dioxide, HDI biuret, various additives, etc. . 2.2 Coating production Various coatings are produced in accordance with the formulated formulation and process requirements.
Table 1 Wind Turbine Dimensions and Painting Requirements Project Specifications Hair Gauge Upright Height / m Electric Maximum Diameter / m Machine Inch Minimum Diameter / m Tube Epoxy Polyamide Zinc Rich Primer /! m body epoxy resin polyamide mica iron oxide paint /! M-tube epoxy resin polyamide zinc-rich primer /! m table epoxy resin polyamide mica iron oxide paint /! m body surface acrylic aliphatic polyurethane cool topcoat (white) /! m coating allows thickness error /! m Note: Quality requirements: 1 meets the standard value requirements; 2 After application, the coating is smooth and uniform, with uniform color, no bubbles, no micropores with 5~10 times magnifying glass; 3 at least 10a does not change color, does not powder, does not fall off, No bubbles, no cracks.
3 Coating (1) Substrate treatment: sandblasting and rusting to reach Sa2. (2) Process: high pressure airless spraying, pressure ratio 32. The inner and outer surfaces of the treated cylinder are sprayed with the first zinc-rich primer in the shortest possible time to prevent re-oxidation and rust; then in order of internal and external The cylinder is painted and constructed. When the ambient temperature is lower than 5, the coating interval should be more than 24 hours.
(3) Inspection of the coating: each coating is inspected, including the surface quality of the coating and the thickness of the coating, which cannot be repaired or recoated; if the coating is completed, the overall coating is inspected, and The focus is on the inspection of the coating thickness.
(4) On-site repair of coating: The wind turbine tower is transported in two sections, each length is more than 20m.) After nearly 1000km of transportation arrives at the scene, there is inevitably coating damage. The damaged part of the coating is polished and repaired with the same type of paint.
4 Discussion 4.1 Evaluation of the coating system The core technology of this project is cited from abroad.
For wind turbines, because they must be in a strong wind and windy environment, and the solar ultraviolet rays in Hexi in Gansu are also relatively strong, the wind turbine's corrosion resistance, weather resistance and resistance are mainly considered. Impact performance.
The anti-corrosion coating is a high-grade anti-corrosion coating system, which has been relatively mature and has a wide range of applications at home and abroad, such as bridges, marine facilities, various large towers, and natural gas or gas storage tanks.
The most typical of these is the painting of Shanghai Oriental Pearl TV Tower, which is expected to have a protective life of 20 years.
The characteristics of the coating system are: (, to meet the long-term anti-corrosion performance requirements of the coating; 0 primer, intermediate paint and topcoat are two-component or three-component type, which can meet the requirements of coating drying at room temperature, avoiding This large-scale equipment can not be baked; the system of the 0 system is very perfect, combining the advantages of zinc-rich primer, micaceous iron oxide paint and acrylic aliphatic polyurethane topcoat, which can meet the anti-corrosion and impact resistance. And weather resistance requirements; 0 overall coating system has a long anti-corrosion life, is expected to reach 4.2 raw materials and coating quality 4.2.1 topcoat with tert-carbonated glycidyl ester modified pure acrylic resin and HDI biuret as film former It can not only ensure the weather resistance of the coating, but also make the coating have good hardness and flexibility, and also has a good coating fullness and other decorative properties; the imported titanium dioxide R902 is used as a coloring pigment, and the coating is also weather resistant. Sex, yellowing resistance and durability are greatly improved.
4.2.2 The paint and primer are made of epoxy resin and polyamide curing agent as film-forming materials. The domestically produced high quality micaceous iron oxide and zinc powder are used as anti-corrosion pigments to ensure the excellent performance of the coating. The film zinc powder content is above 755.
4.3 The construction process has tried to adopt the ordinary air spraying construction process, but since the coated object is a curved surface and the coating area is large, the spraying effect is poor and the efficiency is low, which cannot meet the requirements. After using the high-pressure airless spraying device, the technicians went through the on-site service and discussed with the construction personnel to determine the spraying process conditions and solve the existing problems.
4.4 Existing problems and solutions According to the normal construction process conditions, the production formula is formulated and produced, but the construction is carried out from late November to December. At this time, the temperature in Lanzhou is below 10 during the day and 5 or even lower at night. The construction site is very large and there is no heating facility, so the lower construction ambient temperature has a large negative impact on the construction and coating quality.
Since the primer and the intermediate paint are epoxy/polyamide systems, it is difficult to dry normally under the above-mentioned construction conditions, and the construction period is prolonged; the leveling property of the top paint is very poor, and a large amount of orange peel is formed "at the same time, the coating is affected. Gloss.
At first, it was considered that the special thinner for the topcoat was used in the normal construction conditions. The solubility of the organic resin was poor at low temperatures, resulting in poor leveling. After adding a strong solvent to improve the thinner, the problem was Better, but still not resolved. It was later discovered that the intermediate paint coating before the topcoat was applied was a very slippery surface, which was quite different from the sample made from the sample. The data show that if the epoxy resin/polyamide system reacts slowly, the polyamide floats on the smooth layer of the surface, which makes the coating of the upper coating difficult, and affects the coating performance due to incomplete epoxy/amide reaction.
The crux of the problem lies in the slow curing rate of the epoxy resin/polyamide system, so the problem of drying of the intermediate paint and the poor leveling of the topcoat cause the problem of the straw after the appropriate heating measures are used to force the temperature rise. A better solution has been obtained. At the same time, it has been shown by practice that the addition of a tertiary amine accelerator does not fundamentally solve the problem of low temperature drying.
The special epoxy resin curing agent can solve the low temperature curing problem of the epoxy coating, which is a better solution to the problem after the coating construction. 'Low-temperature curing epoxy resin anti-corrosion coatings' was developed under this circumstance.
5 Conclusions This time, a total of 6 wind turbines were painted, with a coating area of ​​nearly 5,000 m2. After one and a half years of use, the author conducted two on-site inspections, and the coating quality was good. No defects such as shedding, discoloration, cracking, etc. were observed. phenomenon. Painting practice shows that epoxy resin polyamide primer, intermediate paint, acrylic aliphatic polyurethane topcoat system has good performance and matching, but the coating process requires on-site guidance from technicians to ensure timely detection and solution. In this way, the paint can be used properly and its performance should be achieved.
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