Research on the application and development of asphalt anti-corrosion coatings

Pipeline
anti-corrosion
engineering; Underground pipe network transformation project; Chongqing Co.,
Coatings
Co., Ltd. in the national pipe network construction project services; The main characteristics and classification, application and development direction of Chongqing crown asphalt anti-corrosion coating. The anti-corrosion coating technology department focuses on the application of polyurethane asphalt anti-corrosion coating, epoxy coal asphalt anti-corrosion coating and emulsified asphalt anti-corrosion coating.
asphalt is a mixture of polymers with complex chemical compositions, with unique fluidity, good bonding, anti-aging and waterproof corrosion resistance. Asphalt anti-corrosion coatings are widely used in metal anti-corrosion, waterproof and sealing materials. This paper makes a brief description of the development of asphalt anticorrosive coatings in China.
classification and performance of 1 asphalt anti-corrosion coating
1.1 petroleum asphalt polyurethane anti-corrosion coating
1.1.1 two-part polyurethane asphalt
waterproof coating
two-part polyurethane asphalt waterproof coating A composition is composed of polycycyanate (TDI, MDI, etc.) and two-function group or three-function reunion ether synthesis - NCO sealing end of the pre-polymer; Component B is a mixture of asphalt, thinners, fillers, curing agents and other additives under certain conditions. Asphalt can also be added to the A-group, the resulting product appearance smooth, shiny, no asphalt point, good leveling, elongation rate has also increased; Asphalt odor is low, water repugnation, anti-aging performance is good. Shanxi Chemical Research Institute has developed a two-part asphalt-type polyurethane waterproof coating, in the use and storage process of small changes in viscosity, no need to use a large number of organic solvents. They made their own active solvent SR-1 (SR-1 contains some active groups, so in the solubility at the same time, can also be used as a curing agent, can reduce costs. Asphalt-type products and coal tar-type products cost similar, the performance of JC/T500 (92)-96 requirements), and combined with the selection of solvents, plasticizers, to solve the problem of the solubility of petroleum asphalt and polyurethane. Zhang Taiwen added a reactive composition at the same time as the synthesis of polyurethane pre-polymer, changed the structure of polyurethane pre-polymer, so that the resulting polyurethane pre-polymer itself and asphalt solution has compatible, overcome the traditional compatible agent caused by the decline in the physical and chemical properties of the coating film, the resulting polyurethane asphalt waterproof coating surface smooth, flat, and good mobility. Wang Yufen et al. developed the bottom of the ship with polyurethane asphalt rust-proof paint, by the aromatic isocyanate and polyol polyether, as well as coal coking asphalt and rust-proof pigments, such as preparation. It can also be cured into film at -19 degrees C, making up for the defect that the coking asphalt coating of epoxy coal can not be cured at low temperature. Liu Rong et al. used the process of mixing polyurethane pre-polymers with asphalt to prepare a high strength, good elasticity, good waterproof performance of polyurethane-asphalt elastic waterproof coating. The stretch strength of this waterproof coating is 5 to 10 times higher than that of asphalt coating, the fracture elongation rate is increased by 5 to 15 times, and it has good acid and alkaline resistance, weather resistance and water resistance, the coating is seam-free, easy to repair and easy to construct (Table 1).
: (1) the performance of the original polyurethane asphalt coating film / the performance of the asphalt coating film.
1.1.2 single-component polyurethane asphalt waterproof coating
single-component polyurethane asphalt waterproof coating consists of polyurethane pre-polyurethane pre-polymers containing -NCO end-based with asphalt, pigments, fillers, additives, and cured into a film by reacting with moisture in the air to produce radon. Xu Aidong et al. , the original polyurethane asphalt waterproof coating preparation process to improve, in the preparation of polyurethane pre-polymer, will be added to the asphalt, in 80 degrees C conditions fully stirred, so that the asphalt dispersed evenly, the resulting products have excellent storage stability, smoothness, material indicators fully meet the requirements of the JC500-1992 industry standards. Fang an equal person developed a single component polyurethane asphalt waterproof coating, by controlling isocyanate and polyether equivalent ratio, as well as reaction temperature and reaction time synthesis of low-viscosity polyurethane pre-polymer, and by mixing the appropriate amount of thinner to make the product viscosity to meet the requirements of use, and finally achieve solvent-free products. The coating is suitable for waterproofing projects such as underground buildings. Guo Qing et al. prepared a wet curing single-group polyurethane petroleum asphalt waterproof coating with high elasticity and low gentle toughness, and by using special compatible agents, the solubility problem between polyurethane pre-polymer and petroleum asphalt was solved better, so that the coating film properties changed significantly, so that polyurethane performance can be maximized, and the price is much lower than pure polyurethane coating, in line with environmental protection requirements. Chen Qunxuan et al. developed thermal spray fast-curing polyurethane petroleum asphalt coating, by adding petroleum refining by-products and ester-type thinners, so that polyurethane and petroleum asphalt mixed. The coating is a solvent-free thick slurry type fast-curing
heavy anti-corrosion
, which has a good application prospect in buried pipes.
1.2 epoxy coal asphalt anticorrosion coating
epoxy coal asphalt anticorrosion coating is a thick slurry-type two-part coating consisting of epoxy resin, coal coking asphalt, rust-proof pigment and curing agent. It is composed of two components of A and B, the paint material is component A, the curing agent is component B, and is used with the corresponding thinner.
1.2.1 epoxy asphalt heavy anti-corrosion coating
Changxiliang 12) studied the heavy anti-corrosion coating based on epoxy resin and asphalt. The coating overcomes the shortcomings of low softening temperature (surface temperature 50 degrees C), slow drying speed (2 to 3d), and the resulting coating has the characteristics of strong adhesion, high softening point (>80 degrees C), short drying time (<2d), good salinity and acid-resistant alkalinity and high hardness, and its price is lower than epoxy resin coating. The coating is suitable for corrosion-resistant steel structures, tanks, equipment and concrete surfaces in corrosive environments. Liu Zongchen introduced the hydration of epoxy coal asphalt. The water-based epoxy coal asphalt coating developed is not flammable, non-explosive, safe and convenient to use, and is conducive to environmental protection and user's health; Its performance is comparable to solvent-based epoxy coal asphalt coating, suitable for industrial coating, especially for basement and other environments. Water-based epoxy coal asphalt coating formulation can be found in Table 2.
1.2.2 polymer modified epoxy asphalt coating
Qin Guozhi et al. , using rubber modified epoxy asphalt coating, increase the plasticity of asphalt and maintain the water resistance and corrosion of asphalt, while using epoxy resin to improve the adhesion of the coating. Li Chunxuan studied perchlorinated polyethylene modified epoxy asphalt corrosion-resistant coatings. The coating is modified by epoxy resin, coal asphalt, coal tar, perchlorinated polyethylene, and is prepared with fillers, solvents, additives and other substances. Coatings with good flexibility, impact resistance, as well as excellent durability, weather resistance, alkaline resistance, can be widely used in petroleum, chemical and other industries of various industrial equipment and facilities corrosion protection.
1.2.3 epoxy coal asphalt glass scale heavy antiseptic coating
epoxy coal asphalt glass scale heavy antiseptic coating is composed of epoxy resin and treated glass scales of a certain specification, coal asphalt,
pigment
, additives and curing agents composed of two-component normal temperature drying coating. Yu Caixia, Zhao Hongyan, with epoxy coal asphalt resin as a film, with glass scales, pigments, fillers and additives, developed into a thick slurry-type epoxy coal asphalt glass scale heavy anti-corrosion paint, with excellent corrosion resistance, anti-aging and so on, suitable for corrosion protection in harsh environments. Its performance indicators can be found in Table 3.
1.3 Emulsified asphalt anti-corrosion coating
Zhao Shoujia et al. , explored the application of polymer milk night CB403A (solid content 54.8%) in water milk-type asphalt waterproof coating. When the ratio of polymer: asphalt is 1: (1.5 to 2.0), the product fully conforms to the building materials industry standard JC/T408-2005 "water-milk asphalt waterproof coating" in the H-type product requirements. Xu Keqin's asphalt emulsion can improve the compatible of petroleum asphalt, reduce costs and improve waterproofing performance. Liu Dongjie, Wang Yunpu and others used electrochemical polarization curve method and electrochemical AC impedance spectrum to investigate the anti-corrosion effect of emulsified asphalt coating on A3 steel, the results show that emulsified asphalt coating has a large impedance value and low corrosion current density, has a certain anti-corrosion protection effect on metals, and has good anti-corrosion effect in different corrosion media.
2 Application of asphalt anticorrosive coatings
in the polyurethane waterproof coating mixed with the appropriate amount of petroleum asphalt or coal coking asphalt and other water-repugnant materials as fillers, not only can reduce the cost of coatings, more importantly, can play a role in preventing hydrolysis of polyurethane hydrophobic groups, thereby further improving the water resistance of the coating and extending the life of the coating. Polyurethane asphalt coating film has excellent water resistance, impermeability and oil resistance, suitable for water conservancy projects, crude oil storage tanks, general chemical anti-corrosion, ships, harbor terminals, open-air large-scale metal treatment devices and high-pressure water pipes and other occasions. Epoxy asphalt anti-corrosion coatings on metal surfaces, concrete surfaces and other surfaces have a strong bonding force, can effectively resist acid, alkali and other corrosive media erosion, can be used in dry and wet alternating, dark moisture and immersion in harsh environments, such as offshore drilling platforms, shipping ballast cabins, sewage container pipe walls, cooling tower walls, tunnels, underground warehouses, underground pipes and so on.
3 conclusion
asphalt anticorrosive coatings as a class of paint products, will be diversified and green direction of development. High durability, no pollution or low pollution, low cost and easy construction are the development direction of asphalt anti-corrosion coatings.
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