Color coated board production technology development trend
1) Using high quality substrate
The coating process has higher and higher requirements on the surface, shape and dimensional accuracy of the substrate. Outdoor use generally uses small zinc flower flattened hot-dip galvanized steel coils, preferably zinc-free flattened hot-dip galvanized steel coils; in recent years, the trend of zinc alloy hot-dip coils is increasing. An electrogalvanized steel coil can be used for indoor use. The film color coated plate is made of cold-rolled plate, and the sanitary ware is made of aluminum plate.
2) Improve the pretreatment process and pretreatment liquid. The number of equipment is small, the cost is low, and it becomes the mainstream process. The stability and corrosion resistance of the pretreatment liquid are continuously improved. The Cr+3 pretreatment liquid has been used in Korea, and the pretreatment liquid containing no Cr+6 has been developed in Japan to improve environmental protection.
3) Focus on the development of new coatings
Improve general polyester, polyvinylidene fluoride (PVDF) and plastisol to obtain super color reproducibility, anti-ultraviolet, anti-SO2, improve corrosion resistance; develop functional coatings such as pollution resistance and heat absorption.
4) The unit equipment is more perfect.
A uses a new welder. The galvanized sheet has poor weldability, and the unit uses a sewing machine. Mitsubishi Electric has developed a galvanized sheet welder. The strip over-roller does not need to lift the coating roller, which avoids the damage of the strip surface to the roll surface and reduces the length of the strip coated strip.
B new roll coater. The new single-slide coating machine eliminates multiple roll-to-roller errors and adds a more even coating by adding a doctor's knife and sensor. Development of roller curtain type flow coating machine—The paint flows into between two coating rolls. The thickness of the coating film is determined by the gap of the coating roller. The film thickness can be precisely controlled. There is no roller printing on the surface of the coating. The surface of the color coated plate has a unique metallic luster. Roller coating is used for initial coating, and curtain coating machine is used for finishing coating. The liquid coating curtain is applied to the surface of the steel strip, and the coated steel strip does not leave roller marks.
C perfect the curing oven. Adopting the air purification technology, the fresh air must be strictly considered. The air inlet is equipped with a medium efficiency filter and a sub-high efficiency filter. The dust content after the fresh air is too much <1.5mg/Nm3; the indirect combustion post-combustion system uses a coke oven or a mixture. When the gas is used as fuel, the heat is concentrated in the waste gas incinerator, and the supplemental air temperature is heated to a high enough level to be sent to each section of the curing furnace, and the combustion products do not enter the curing furnace; the section temperature control technology, the temperature of each section is simultaneously adjusted to the hot air. And the realization of cold air volume, with a complete set of hot and cold air control system to improve heat utilization; use incinerator flue gas preheating to supplement the wind, using regenerative heat transfer technology (RTO), exhaust gas temperature <200 °C.
5) Development of cold embossing production technology
Cold embossing is less expensive than hot embossing and is widely used in North America. The embossing machine is similar to the two-roll flattening machine. The upper and lower rolls are engraved with patterns, and the color plates are pressed and deformed. The leather strips, brick patterns, granite patterns, etc. can be obtained by changing the rolls, and the appearance is three-dimensional and high in strength. The cold embossing machine can be set on line or off-line, with a rolling force of up to 50t and a speed of up to 210m/min.
6) Focus on product diversification, functionalization, and high-end
A deep-drawing color coated board. Based on the detailed analysis results of the deformation state of the coating film during processing, a coating film corresponding to the deformation of the steel sheet was developed, and a precise resin design was made to develop a deep-drawing color-coated plate with good adhesion and corrosion resistance. .
B "Pomelo peel" color coated board. Adding a few micron-sized additives to the coating, floating on the surface of the film, and having a fine uneven surface on the surface of the grapefruit skin, it is necessary to precisely control the surface irregularities, form appropriate wavelengths, and use the "post-coating" plate to form the same appearance, grapefruit The surface of the skin color coating makes the defects inconspicuous and concealed.
C anti-static color coated board. Widely used in office automation, video recorders and other aspects. The coating film charging voltage can be reduced by 1/4, the dust adhering to the color coating plate is greatly reduced, and the process of wiping off dust and the like can be reduced during processing and assembly, and good addition, moldability and chemical resistance are still obtained.
D resistant to color coated plates. Kitchen appliances such as refrigerators should be resistant to oil, seasoning and detergent. The "inclined coating film" with hard surface and flexible inner surface was developed. The polyester resin was combined with the hardened melamine resin to increase the molecular structure density. After the film was heated, the surface of the film hardened by melamine accumulation, and the surface of the coating film was hard to be contaminated. The inner layer of the coating film is less flexible and easy to process.
E high heat absorption color coated board. The high-performance and miniaturization of electrical products increases the heat load per unit volume of electrical appliances, and the heat inside the machine needs to be quickly and effectively dissipated. The coating film of the heat-absorbing color-coated plate can absorb the infrared rays generated by the heat through the special design of the resin, the additive and the pigment molecule, and then dissipate through the steel plate, so that the temperature inside the electric machine is lowered by about 10 ° C, and the heat dissipation of the electric appliance can be omitted. Disperse and reduce the vents.
At present, the production of coated plates in China has achieved unprecedented development, but there are also many problems, such as the shortage of tin-plated substrates and electro-galvanized sheets; the hot-dip galvanizing of building materials, the coating of color-coated plates is too thin, and the product quality is not good. In the future, the market will be faced with disorderly competition. In the future, we will face problems such as hot-dip galvanizing and color-coated plate production capacity. We can only solve these problems continuously, strengthen industry self-discipline, integrate into the international market, and strive for survival and development in competition.