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Development status and prospects of color coated steel plates

development status and prospects of color coated steel plates

November 8, 2004

development status of international color coated steel plates

production technology of color coated steel plates was first established in the United States in 1927. Since the 1960s, the production of color coated plates has developed rapidly, with the United States and Japan having the most color plate production lines, the largest production capacity and the most complete varieties and specifications. In foreign countries, color board has been widely used in construction, home appliances, automobile manufacturing and other industries. With the growth of color coated board consumption and the continuous expansion of application fields, as well as the continuous improvement of users' requirements for its variety, quality and performance, all kinds of new technologies for color plate production have been developed and applied, and the varieties of color plates have gradually developed in the direction of diversification and upgrading

in China, the consumption and production of color plates began to rise in the late 1990s, and its growth momentum was extremely rapid. By the end of 2003, 124 enterprises had built 169 coating units, with a production capacity of 8.74 million tons, including 7 member units of China Iron and Steel Industry Association, with a production capacity of 1.04 million tons; 162 non member units with a capacity of 7.7 million tons. However, because most production lines are affected by factors such as low equipment level, weak technical force and unstable raw material supply, the unit operation rate is low. At present, the domestic color plate market is still in a state of half self-produced and half imported, with supply exceeding demand. In 2003, the total domestic output was 1454600 tons, the import was 1101600 tons, the export was 16200 tons, and the total apparent consumption was 2539900 tons

domestic low-level repeated construction has led to vicious competition in the color coating market, and many units with tens of millions of investment have been shut down when they are put into production. The China Iron and Steel Industry Association predicts that the domestic demand for color plates will reach 4.3 million tons in 2005 and 8 million tons in 2010, of which the proportion of plates used outside buildings will be greatly increased. According to the data of ECCA 2003 annual meeting, in North America, the proportion of color coated steel plate and color coated aluminum plate as construction plates is 66% and 53.3% respectively. At present, China's consumer market is mainly in the construction and decoration industry. The proportion of color plates used in construction in 2003 was as high as 95%. The application in the household appliance industry is still in the stage of small batch trial, and the application in the transportation industry has basically not started. Therefore, color coated panels still have broad market prospects in China

color coated plate production process and coating

color coated plate mainly includes ordinary coated plate and special color coated plate. At present, domestic ordinary coated steel plate is mainly used in the construction industry, The process flow is as follows:

the basic production process of coated plate: uncoiling → double cutting and shearing → the best way to find the fault sewing machine → (pre degreasing) → looper → degreasing and cleaning → chemical coating treatment → drying → initial coating → curing and drying → cooling (water, air) → fine coating surface paint → curing and drying → cooling (water, air) → looper → coiling

substrates for color coating include cold-rolled annealed sheet, ordinary SPI said zinc flower finishing hot-dip galvanized sheet, small zinc flower finishing hot-dip galvanized sheet, non zinc flower hot-dip galvanized sheet and electro galvanized sheet. Among them, the number of cold-rolled plates used for color coated substrates is decreasing, and electro galvanized plates are gradually replaced by hot-dip galvanized plates. The number of Galfan, galvalume, Galvanneal and Electroplated Zn Ni steel coils as substrates is increasing, and color coated plates with stainless steel as substrates appear, especially with the development of domestic Baosteel After the galvalume production line of WISCO is put into operation successively, the color coated plate with GL as the substrate will replace the imported one. In addition, color coated substrates for construction are developing towards thin specification (<5mm), large width (> 1500mm) and high strength (UTS> 600MPa). Color coated substrates for household appliances have higher and higher requirements for surface quality. At present, the maximum width of color plates that can be produced in China is 1600mm (WISCO line 2)

epoxy primer is the most classic primer type, which was used in almost all types of color plates before 1990. It has the best anti-corrosion performance under the film, and has strong adhesion with the pretreatment layer and most of the topcoats. However, due to its high PMT and high curing energy consumption, it cannot match the finish paint to 0t and 1t. Polyester primer is a new primer developed by European and North American coating companies in recent years. Its corrosion resistance is comparable to that of epoxy primer, with low PMT (<200 ℃), and its high flexibility is especially suitable for the production of color plates for household appliances with high requirements for t-bending. Waterborne acrylic primer is another new primer, which belongs to environmental protection products. Its PMT is lower (160 ℃), and other properties are similar to polyester primer. However, it is easy to lead to the decline of the chemical stability of the coating, so it is still not generally accepted

the comprehensive advantages of polyester in corrosion resistance, decoration, cost and other aspects make it occupy a leading position in the color plate finish, and the consumption accounts for more than 50% of the total finish. In addition, PVC plastisol is mostly used as the topcoat for outdoor buildings in Europe, accounting for 31% of the total consumption of topcoats; The modified polyester used in the United States accounts for 39%

roll coating method is the most widely used in the production of color coated plates, accounting for about 85% - 90%. The treatment of the process section is that the dipping roller of the roller coater is dipped with liquid paint, the paint is applied to the upper and lower surfaces of the pretreated strip steel by the coating roller, and then enters the curing furnace for heating and baking, the solvent in the paint is completely volatilized, and the waste gas containing solvent is discharged and sent to the incinerator for treatment. After baking and curing, the coating is cooled by water quenching and dried by hot air. Roll coating process is usually limited by the thickness of one-time film of roll coating machine and the ability of baking curing furnace. If the product requires a large film thickness, it requires multiple coating and baking, and the perspective of consolidating the world is particularly important. Therefore, in order to meet the requirements of different coating thickness, roller Xu process has one coating and one drying, two coating and two drying, or even three coating and three drying. At present, the widely used roller coating process is two coating and two drying. At present, the maximum process speed of domestic color coating units is 160m/min. in the United States, many units can operate at a speed of more than 180m/min, which greatly improves the production capacity

powder coating method is a new process: the surface of the pretreated substrate is coated with powder adhesive, which is cured by induction heating, and then cooled by an internal water-cooled roller before entering the powder coating device. The powder coating device is in a strong electrostatic field, and the powder rotating brush generates a coating powder cloud. The solid coating particles of the powder cloud have a high charge, which flies to the substrate running at a high speed, producing enough boundary penetration, The powder particles are uniformly deposited on the surface of the strip steel. At present, there are five powder color coating lines in the world, with the coating strip width of 1300mm, and the process speed of the unit has reached 100M/min

color plate enterprises should cooperate with upstream and downstream manufacturers for win-win results

for domestic color coated steel plates, developing new varieties of color coated steel plates and improving the technical content and added value of products is an urgent problem to be studied and tackled. In the next 10 years, China's color coated steel plate market will be better and better, and there is a lot of room for development. However, facing the increasing degree of integration of the international market, if the traditional requirement to reach a specific zinc content as the standard is higher, the competition will become more and more intense. Therefore, color plate manufacturers should always maintain a close cooperative relationship with paint manufacturers in the upper reaches of the industry and home appliances manufacturers in the lower reaches of the industry, so as to face the market together and achieve win-win results

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