The effects of polymer additives on the operating windows of slot coating

• Published in: Polymer engineering and science Vol. 44; no. 10; pp. 1970 - 1976
• Main Authors: Yang, C. K., Wong, D. S. H., Liu, T. J.
• Format: Journal Article
• Language: English
• Published: New York Society of Plastics Engineers, Inc 01.10.2004; Wiley Subscription Services; Blackwell Publishing Ltd
• Subjects: Additives; Applied fluid mechanics; Exact sciences and technology; Fluid dynamics; Fundamental areas of phenomenology (including applications); Hydrodynamics, hydraulics, hydrostatics; Physics; Polymers; Protective coatings; Chemical solution; Additives; Cellulose(carboxymethyl); Glycerol; Experimental study; Roller coating; Quantity ratio; Lining processes; Manufacturing defect; Investigation method; Flow visualization; Acrylamide polymer; Liquid flow
• ISSN: 0032-3888; 1548-2634
• DOI: 10.1002/pen.20200

An experimental study was carried out to investigate the effects of polymer additives on the operating windows of slot coating. Two polymer additives—carboxylmethylcellolose (CMC) and polyacrylamide (PAA)—were added to Newtonian glycerin solutions as test fluids. The flow experiment was performed on a lab coater. A flow visualization technique was employed to observe the shapes of coating beads. It was found that three types of defects appear at the lower bound of the operating window, i.e., ribbing, air entrainment, and break lines coupled with dripping. Adding a small amount of polymer additives has little effect on the operating window if the defect is ribbing, but it will expand the air entrainment region. The coating speed can be increased significantly if the defect is break lines coupled with dripping. Polym. Eng. Sci. 44:1970–1976, 2004. © 2004 Society of Plastics Engineers.