Steel structure anti-corrosion new material - winter polyp

Introduction
Steel structure anti-corrosion construction process is generally surface treatment and anti-corrosion coating, from the most common primer finish to increase the middle layer, the most classic coating structure: zinc-rich (inorganic zinc-rich, organic zinc-rich) and epoxy cloud iron and acrylic polyurethane (fluorocarbon paint or polysilica, etc.). This system is widely used in steel structure plant and mesh sheds, bridges, pipe gallery frames, wire rods, photovoltaic power stations, wind turbines and some marine projects, and achieves long-term corrosion-resistant effects. However, this classic supporting coating structure multi-layer coating time -consuming (long layer coating interval), to some short-term maintenance or emergency projects to bring insurmountable difficulties

. This paper discusses the excellent characteristics of the winter polypropyl and the application of the single-layer supporting process with zinc-rich bottom coating in the corrosion prevention of steel structure, this novel coating supporting process is an innovation of traditional steel structure corrosion protection, especially in environmental protection, labor saving, reduce material costs is very obvious.
-day winter polyp research and development background
1.1 no VOC construction exemption conditions
after anti-corrosion coating research and development personnel and anti-corrosion construction technicians continue to explore the practice, a steel structure anti-corrosion new material - tiandong polysaccharies to solve the above difficulties, and can meet the environmental requirements of the construction exemption conditions without VOC. According to the latest GB37822-2019 Volatile Organic Organics Unwed Emission Control Standard 7.2.1, VOCs are ≥10% of the quality of VOCs-containing products, Its use process should be closed equipment or in an airtable space operation, exhaust gas should be discharged to voCs exhaust gas collection and treatment system;
Figure 1 steel structure plant anti-corrosion
1.2 environmentally friendly coatings winter polyp,
including but not limited to the following operations: coating (spraying, immersion, spraying, roller coating, brushing, coating, etc.). This strictly defines the scope of coating environmental restrictions, VOCs quality ratio≥ 10% of the construction must be set up exhaust gas collection and treatment system (this is the conventional heavy anti-corrosion construction site difficult to meet the hard requirements, reverse paint production enterprises or use units must use water-based paint or solvent-free paint) that is, no solvent or solid content> The winter polyp is in full compliance with the above-mentioned requirements.
Figure 2 Bridge steel structure anti-corrosion
-day winter polysaccharide excellent performance and supporting system
2.1 days of winter polysaccharide corrosion resistance and applicable period
days of winter polysaccharide is a new type of fat family, slow reaction, high-performance coating material, known as the third generation of polysaccharides, in fact, is a kind of fat family mid-amine. When the coating is exposed to ultraviolet light requires a high degree of stability, it is necessary to use a fat family coating system - winter polysacchargium. Polytinate viscosity is low, and HDI trimer reaction speed can be different to replace the base group, gel time from 5 min to 120 min, construction life can be extended from 5 min to more than 2 h, spray together can reach 0.6 mm; no pores on the coating surface; the formulation system has a wide adjustable range; it has good resistance to ultraviolet light, long luster, color stability and non-yellowing; and the material loss during spraying is small, and the solid content can be adjusted from 70% to 100%.
days winter polysaccharides with high solid content and low viscosity (solid content >90%, or even up to 100%) ultra-strong UV resistance, wear resistance, good flexibility, resistance to less than 5% acid and alkali and some chemical media, thick coating construction, can be sub-zero rapid curing and so on. In accordance with the "HG/T 5368-2018 polytianmen anti-corrosion coating" standard, the winter polyurethane DTM can be applied to C4 and below light anti-corrosion occasions alone; It can be used as a primer such as varnish and epoxy, and the companion scheme has been approved and added to the latest version of ISO12944-5:2018 color paint and varnish protective paint system corrosion protection against steel structures.
2.2 surface treatment requirements and coating system supporting
days of winter polysaccharides and zinc-rich primer matching binding force>5MPa, salt-resistant fog up to more than 3000 h. The most classic steel structure corrosion-resistant coating from zinc-rich (inorganic zinc-rich, organic zinc-rich) and epoxy cloud iron and acrylic polyurethane (fluorocarbon paint or polysilica, etc.) can be optimized for: zinc-rich (inorganic zinc-rich, organic zinc-rich) and winter polysaccharide coating system, greatly reducing the construction cycle and labor costs.
this anti-corrosion coating coating supporting system not only meets the requirements of construction environmental protection, but also a technical revolution and coating innovation. The selection of zinc-rich primers in the system requires the surface treatment of steel structures to meet the requirements of Sa2.5 grade standards and related soluble salts as stipulated in the Visual Assessment of Surface Cleanliness of Steel Surface Treatment before GB/T 8923.1-2011 coating. When the metal surface is cleaned by injection, a certain surface roughness or surface profile is obtained. The formation of roughness will significantly increase the area of the metal surface, while obtaining a lot of anchoring points, easy to cause the coating film at the peak is thinner, and too large roughness will be due to the paint on the substrate immersion of poor resulting in the coating corrosion and attachment of the reduction. After removing rust, dirt and old paint, the steel surface is not clean enough to be painted, especially soluble salts are more harmful to the coating.
soluble iron corrosives may continue to contaminate rusted steel because corrosive substances such as salts are almost colorless and can be hidden deep in pitting so that they cannot be effectively removed. Clean surfaces with a surface treatment rating below Sa2.5, soluble corrosives are hidden under layers of iron oxide. These corrosion products are usually water-soluble iron chloride and iron sulfate, and the coating will cause the paint film to blister during later use. Therefore, these soluble salts must be removed before painting, or reduced to an acceptable standard. The surface treatment of the steel structure conforms to the above roughness and cleanliness before the coating can be carried out, under normal circumstances, the thickness of the zinc-rich base coating is basically controlled between 60 and 80 m.
days winter polysaccharides in a variety of corrosive environment applications
if underwater immersion or weather resistance requirements are not high in the occasion can choose such as GB805B-100 polyether-modified pre-property curing type winter polysaccharides, its green environmental protection, solvent-free, low viscosity, an facade construction up to 500 m thick, with a longer construction application time. Brushing, rolling, spraying can be, flexible and convenient construction. Paint film strength is high, flexibility, wear resistance, excellent anti-flush, and zinc-rich can match the advantages of good.
but the polyether structure determines that its weather resistance does not meet the corrosion environment requirements of C5. In outdoor weather-resistant occasions, it is recommended to choose HDI trimer type of adipose group winter polysaccharids, with excellent weather resistance and aesthetic performance. Fast-drying fat family winter polysaccharides in manual brushing, rolling coating construction applicability is not as good as polyether modified pre-cluster curing type winter polysaccharides, the application period by the construction of solid content is more affected. For example, the application period can be up to 4 h when the quality is 75%, 0.5 h at 85%, more than 90% and solvent-free less than 10 min, so if you want to meet voCs<10% of the environmental requirements, you can use a dedicated two-part Spraying equipment for construction, coating thickness can be up to 200 m, consumption of about 0.5 kg/m2, can be normal curing at -10 degrees C, at room temperature table dry 20 min, dry 40 min, can be quickly put into use.
another technical solution is the use of gel time 2 h of slow-dry poly-tianmen holly resin made of winter polysaccharide paint, coating application period can be extended some, but the drying time will also be extended to 8 h. Zinc-rich (inorganic zinc-rich, organic zinc-rich) and winter polysaccharide coating system can meet the ISO-12944:2018 supporting system thickness requirements, in the C5 atmospheric corrosion environment can reach 30a service life.
Figure 3 Steel structure corrosion protection
Figure 4 wind turbine corrosion protection
Figure 5 offshore drilling platform steel structure
Conclusion
With the rapid growth of the steel structure industry's technological progress and usage, steel structure coating, especially anti-corrosion coating quality requirements, service life and cost-effectiveness have correspondingly put forward higher goals. According to incomplete statistics, in 2019, the use of steel structure in China exceeded 70 million t, the number of materials used for corrosion-proof coating is huge, labor costs, coating materials costs, time cost is the largest cost of construction and construction costs. In the face of huge construction cost pressure and environmental restrictions, the construction department has been looking for the best coating materials, whether from the cost-effective or from environmental requirements, the winter polyp has irreplaceable forward-looking advantages. Zinc-rich (inorganic zinc-rich, organic zinc-rich) and winter polysaccharide coating system in large-scale steel structure corrosion-resistant coating industry will show strong vitality, and tend to improve. Enso and the country's top producers of winter polysaccharides to cooperate with zinc-rich (inorganic zinc-rich, organic zinc-rich) and winter polysaccharide coating system successfully applied to the outer wall of wind turbines and auxiliary steel structure corrosion-proof coating field, and achieved good economic benefits and practical expected results.
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