FOCUS ON COIL PROCESSING
Image : Brillux Industrial Coatings .
of shapes , depending upon the end use . The coil coating process itself offers a range of economic and environmental benefits . It is a closed loop process so the release of harmful elements is eradicated . All solvents / organic compounds are captured and treated before emission .
The process also provides a reported coating application efficiency of over 90 %, which is significantly higher than other application techniques . Pre-painted metals can also be fully recycled , providing further environmental advantages .
The method includes cleaning and chemically pre-treating the metal surface . Before the final product is created , one or both sides of the metal are painted or coated with powders or liquids which are then dried or bonded with plastic films . Coil coating employs processes such as cleaning ; pretreating ; prepriming ’; prepainting and coating flat metal coils of steel or aluminium . The coated metal coil is subsequently supplied to equipment manufacturers to be formed into a range of ready-painted parts .
Coated coils ( image : Dana Steel .)
Prepainted aluminium coil ( image : Haomei Aluminum ).
Pretreatments are often used to help provide improved corrosion resistance of the substrate , often by passivating or converting the metal surface , typically via phosphate or chromate chemistries . The type of chemical treatment varies with the type of metal being used . Additionally , pretreatment can enhance performance of the fully coated product by adding topography to the metallic surface to help facilitate the bonding between the metal and the coating .
The continuous coil-coating process provides high standards of quality assurance through coil-to-coil consistency and has significantly lower environmental emissions than batch or post-painting processes . This reduces the need for re-work and lowers non-conformance levels and associated costs . By utilising prepainted metal in their process , manufacturers can also eliminate their paint lines which are usually the major bottleneck in their operation .
“ Although the organic coatings used in coil coating are generally thinner than post-applied powders and films , they still give better in-service performance . So , you use less paint which minimises resource consumption and enables you to cut down or even eliminate maintenance and re-painting ,” commented ECCA ( The European Coil Coating Association ).
“ The cost of complying with environmental regulations is significantly reduced , or even eliminated . The cost of the disposal of hazardous waste associated with the painting operation is also eliminated . Scheduling problems and the costs associated with batchtype processing are minimised or removed altogether . Since input material is more directly related to output , the processing time is reduced and stocks are minimised ,” it added .
The market for coil coatings
According to analyst Mordor Intelligence , the coil-coatings market size is estimated at US $ 1.51 billion in 2024 and is expected to reach US $ 1.86 billion by 2029 , growing at a CAGR of 4.32 % from 2024-2029 .
“ The COVID-19 pandemic negatively impacted the market . The pandemic jeopardised building construction and engineering projects worldwide in numerous ways and many projects were closed or halted , decelerating the growth of the coil coatings market during the pandemic crisis . However , the industry witnessed a recovery in 2021 , thus rebounding demand for the market studied ,” commented the analyst .
“ Over the short term , rising demand from the building and construction industry and growing environmental influences as well as advancing technology are the major factors driving the market studied . Conversely , increasing demand for lightweight materials in the automobile industry is expected to hinder the studied market ' s growth . However , increasing demand for fluoropolymer coatings for architectural applications will probably act as an opportunity ,” it said .
According to the study , Asia-Pacific dominated the market in terms of consumption
due to the rise in production and export of precoated metal sheets in the region because of “ high production of finished steel and manufacturing of end-user products .”
“ The coil-coating market is closely tied to the construction industry . Coil coatings are extensively used in building and construction applications including roofing , cladding and insulation . The increasing demand for residential and commercial buildings fuels the need for coil coatings , driving market growth ,” explained market analyst , Data Bridge Market Research .
The coil-coating market is also driven by rapid industrialisation in emerging economies . Industrial sectors such as automotive , appliances and HVAC ( heating , ventilation and air conditioning ) require coil-coated materials for their products .
Steps on a modern coating line
■ Mechanical stitching of the strip to its predecessor .
■ Cleaning the strip .
■ Power brushing .
■ Surface treatment by chemical conversion .
■ Drying the strip .
■ Application of primer on one or both sides .
■ Passage through the first curing oven ( between 15 to 60 seconds ).
■ Cooling down the strip .
■ Coating the finish on one or both sides .
■ Passage through the second curing oven ( between 15 to 60 seconds ).
■ Cooling down to room temperature .
■ Rewinding of the coated coil .
ISMR April 2024 | ismr . net | 35