Coating Double roll processes

Roll coaters were first used on papermachines in the late 1920 s. Roll coaters, as their name implies, use a series of rolls to apply coating to the paper. The coating color is added to a reservoir between the first two rolls that are set to meter the amount of coating to be applied to the sheet. The next several rolls oscillate as they turn distributing the coating evenly across the whole width of the rolls. The paper web passes between the final two rolls, which transfer the coating onto the paper surface. Depending upon the specific process, both sides of the paper may be coated simultaneously or each side can be coated sequentially. A double roll coater is illustrated in... 

Coated substrates involve different materials such as coated credit cards, paper, woven and nonwoven textiles, plastic or aluminum films and sheets, and roll coverings. Calender lines can process one coated side, both sides, or laminated (multiple substrates coated between each substrate). Calender with three rolls is usually sufficient for one-sided coating. However four rolls are used for extremely thin coatings. The 4-roll calender can be used for double-sided coating that is applied simultaneously on both sides. Specialized calendering equipment is used for certain products such as credit cards, floor tiles, and window curtains. 

---