The opportunity to accurately and cost-effectively assess coating formulation chemistry, material application, and the drying process is critical in pursuing the commercial viability and overall performance of products and their related end-use applications. The ability to shorten the development cycle with empirical evidence that is as close as possible to real-world processes gives development engineers and manufacturers a competitive advantage in the global marketplace.
Coating and drying requirements vary greatly by manufacturing process and materials input. The drying behavior of coatings on web-based substrates typically has significant impact on the process design and economic viability of industrial coating processes. There is obvious risk in moving ahead with pilot-line production when there is missing data or limited information, especially when significant capital expenditures are involved. Opportunity for success is increased by accurate process and performance data.
In the early development stages, advanced materials are often available in limited quantities, thus making traditional pilot-scale trials impractical. Yet, the ability to characterize drying behavior at an early stage offers key information for timely process design decisions before making a heavy investment in time and capital.
Fulfilling the Go-to-Market Strategy
As important as the field of web drying is in numerous industrial processes, investigators have continually added to the body of knowledge and methodologies over the past few decades. Advances in drying characterization and modeling have played a significant role in the design and operation of dryer hardware, and the decision about what to take to market.
Today, the role of drying experimentation and process characterization during the development of coating formulations is recognized as a useful tool, especially in the early stages of product development. The goal is to increase technical certainty, which in turn helps confirm product end use and commercialization.
Lab-Based Bench-Scale Drying Experiments
New laboratory methods that provide early returns on key data points from coupon-scale samples give product developers the insight to quickly and cost-effectively assess coating chemistry and processes, substrate performance, and overall drying characteristics via bench-scale testing.
The development operations in the B&W MEGTEC drying lab offer a highly instrumented and sophisticated test cell that provides practical information useful in early scale-up work or process troubleshooting. This is a very advantageous test environment for situations where test materials, timing, funding, or other resources are limited.
Compared to moving webs in pilot- and production-scale settings, the coated web specimen in the bench test cell remains stationary and therefore can be observed over time, making it possible to capture the complete drying run history. This allows investigators to employ a number of measurement techniques to observe the sample, often providing more information about the coating history compared to a pilot- or production-scale venue.
Drying test cells are generally arranged to process with heated convection air or infrared emitters and simultaneously detect the removal of water or organic solvent as the test run proceeds.
The ability to speciate water and organic solvents in coatings provides an enhanced capability over gravimetric methods alone. The current technique deployed in the B&W MEGTEC drying lab incorporates both humidity and FID sensors to quantitatively observe the drying of water-based, organic solvent-based, and combination water and organic solvents in coating materials.
This approach can also be helpful when drying organic solvent-based coatings on paper or other web substrates that contain moisture. Solvent from the coating can be quantitatively recognized while simultaneously observing the drying of moisture from the web. Further, the visual assessment of the specimen surface with a video microscope makes it possible to see the formation of defects or optical attributes during the drying run.
When combined with measurement and recording the air and coating specimen surface temperatures throughout the test run, drying characterization can capture performance data of great value to coating formulators, plant process engineers, and equipment designers.
For more information about bench-scale testing of small-size samples and the B&W MEGTEC drying lab, contact BJ Kays, Senior Process/Sales Engineer, at firstname.lastname@example.org; 1-920-336-7515, ext. 3140; or visit www.babcock.com/megtec