The coffee-ring effect of a coated narrow stripe approximately 350 lm wide was examined. The coating solution was based on a new formulation with a specific application for the production of color filters used in liquid-crystal display panels. The basic components of this formulation were color pigments, solvents, and a novel alkali solution resin. The resin was a copolymer consisting of methacrylic acid, hydroxyl ethyl methacrylate, and methyl methacrylate. Three solvents with different boiling points were used: propylene glycol methyl ether acetate, methyl ethyl ketone, and tetrahydrofuran. The formation of a coffee ring on the coated stripe was mainly dependent on the solvent evaporation rate and the acid value of the copolymer. The acid value determined the strength of the hydrogen bonding of the copolymer. Fourier transform infrared analysis revealed that the intramolecular hydrogen bonding of the carbonyl groups of hydroxyl ethyl methacrylate was one of the critical factors affecting the formation of a coffee ring. The other factor was the rate of solvent evaporation. A proper adjustment of the acid value combined with a highly volatile solvent could effectively eliminate the formation of a coffee ring. V C 2010Wiley Periodicals, Inc. J Appl Polym Sci 120: [1555][1556][1557][1558][1559][1560][1561][1562][1563][1564][1565] 2011
A novel idea was proposed to the design of a coating die for delivering suspensions. In addition to considering the lateral flow uniformity of the liquid sheet, particle sedimentation is also avoided by maintaining high shear rates inside the die. Only two shims are designed to deliver the coating suspensions, and these two shims are easy to make and flexible for replacement. Two theoretical tools were developed for die design, i.e., one-dimensional lubrication approximation combined with the optimal design and three-dimensional finite element simulation. The coating suspension was assumed to obey the Bingham model. It was found that the one-dimensional lubrication approximation can offer the basic optimal design, whereas edge effects can be minimized through three-dimensional finite element corrections. Three experimental dies were built: a T-die, a fishtail die and a coat hanger die based on the optimal design. Experimental results verified the theoretical predictions. Figure 4. Three different dies in the experiment: (a) fishtail die, (b) T-die, (c) coat hanger die. Asia-Pacific Journal of Chemical Engineering COATING DIE DESIGN FOR SUSPENSIONS 121
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.