Here are 3 web handling rules Tim Walker keeps forgetting to tell you.Read more
Music City plays host to converters attending the Flexographic Technical Assn.'s annual conference and exhibition.Read more
When looking for process, product, and profit improvements for your PSA tapes and labels, consider going back to the drawing board.Read more
Folding carton and corrugated converters will find equipment displays and educational opportunities in die-cutting, foil stamping, embossing, and more.Read more
News | New Products
The 9th Annual IMDA Awards Competition will recognize IML packaging, IMD durable products, and labels in multiple categories
The companies will develop inspection solutions for sectors including labeling and packaging and also will co-develop print quality assurance solutions
The Graphium hybrid digital inkjet press has many new features, and company also announces new label production workflow
The XN Cantilever Load Cell is loaded with features said to make it a cost-effective drop-in component for tension measuring
Company seeks patent for its UltraPerf Rule for corrugated board, said to reduce corrugated board wrapping and improve dimensional accuracy control
COMET will expand its electron beam business with the purchase, adding PCT’s BroadBeam line of EB solutions
The event, again co-locating with CPP EXPO, features a floor area for unique print applications and a pavilion focusing on print of the future
Directories | Reports
PFFC brings you exclusive White Papers from our online sponsors.
Visit Kelly on Static from Static control expert Dr. Kelly Robinson, president of Electrostatic Answers; Kelly has 27+ years of experience in problem-solving and consulting.
Visit Tim's Web Lines to handle and wind your paper, film, foil, and similar products. Take advantage of Tim’s 25+ years just like over 100 converters have.
Visit Mark's Coating Matters from fluid coating expert Mark D. Miller; Process improvement and project management for precision roll-to-roll coating applications.
Visit Marketing Mojo for dynamic marketing insights from Stephanie Millman that inspire new ideas on how to stay on top of your customer’s mind.
Visit Yo’s Yarns to share the thoughts, impressions, experiences, and news that impact the converting industry. . . or anything else that happens to be on her mind!
Visit Tom's Poly Ploys, where Tom will be writing on various topics that the typical polymer processor would encounter on the job.
- September 24, 2013
If you'd like to hear from Mark Miller's own lips rather than read his column titled, "Coating Matters | Multilayer Coating," click on his podcast below:
What do you do when you want to have more than one functional layer on a given substrate? Oh yeah, and you want to lay each layer down at the same time… Welcome to simultaneous multilayer coating! A functional technique via slot die coating technology.
Let’s say you would like to have an optical film that enhances viewing, brightens the display, reduces glare, and doesn’t have static when being handled as a film. Usually one coating would not be capable of providing all this functionality in one coated liquid. In the past that would mean multiple passes through a coating station, multiple curing steps, loss of film with winding and rewinding, contamination from multiple process steps, and scrap due to handling. I have listed 4 functional fluids in the example above and with the right chemistry, the right process, and the right technical design you can find a solution to this quandary.
The only caveat with coating multiple fluids at the same time is that the technology must be pre-metered. The fluids are fed through separate channels and combine only after they have left the slot die cavity. Internal combination of these low viscosity fluids would lead to turbulent mixing. A common version of multilayer slot die coating is referred to as a slide die. Slide dies are manifolds stacked one on top of another so the fluid flows up and out for the slot cavity, then “slides” down the face of the die to the next cavity where the fluids stack and stack and stack until cascading onto the substrate below.
Slide coating is very familiar to those from the photographic film industry, but multilayer coating need not go the way of the analog camera. Coating multiple fluids at once can have significant advantages if applied properly. With these great advantages also come great considerations: complex rheology and flow dynamics, interlayer adhesion and surface tension, possible diffusion, edge effects, and fluid substrate interaction. Depending on the flow calculations of the fluid, curved or chamfered lip geometries may be required to reduce eddies from forming in the layered fluids. Vortices can cause mixing, which is not wanted in multilayer slide coating. If you thought product and process development engineers needed to iterate for a standard project – you haven’t seen anything yet! Developing the viscosity and surface tension combination that works appropriately for the separation lines of equipment and the combining fluids can take time and patience.
Another area of interest is coating two sides of the same substrate at the same time. This is a process technique that requires at least one TWOSD technique in combination with a traditional or advanced coating technique for the first layer. The trick is not limited to coating however, as the curing of a double-sided substrate is more complex than it seems. Whether you want to develop multi-functional coatings or dual-side products, it’s time to find a partner and work on the chemistry to get it right.
If you are interested in discussing this concept further, contact Mark D. Miller, Founder and CEO of Coating Tech Service, LLC (www.coatingtechservce.com) at firstname.lastname@example.org or (612) 605-6019.