Study of the temperature profile during industrial coating process

Abstract: Drying rate during industrial coating application is important to understand because drying a coated paper requires energy. If an unnecessary high amount of energy is used to dry paper, a fast evaporation rate can be achieved which can result in defects of the coated surface.   In this bachelor’s thesis, temperature profile during industrial coating application was studied. An industrial pilot trial on a coating machine was implemented at UMV coatings at Säffle, Sweden. Two boards with grammages of 210 and 350 gsm were used, where cardboard 210 gsm was precoated on the backside with two different precoatings. Where the two precoating differed in latex content and type of Hydrocarb. Board 350 gsm was not precoated. Temperatures between 65 to 85 oC were achieved in the drying section, depending on which substrate that was used.  Laboratory tests were also performed to investigate the relationship between surface temperature and dry content of a substrate during drying. As the temperature and time increased, did also the surface temperature and dryness of the samples. It was assumed that the temperature readings from the pilot coater could be correlated to the dry content of coating color.    The results from the study showed that by decreasing the dry content in a coating, a higher surface temperature was obtained during industrial- and laboratory drying due to the increase in heat transfer rate. Results showed also that when fraction of clay in a coating was decreased, a higher evaporation rate and higher surface temperature was obtained during drying.