April's Converting Machinery/Materials show in Chicago displayed many new patented technologies--including several first-time achievements--in flexographic printing, coating, winding, and web inspection. The new technologies are more flexible, less polluting, and above all, faster.
Milestones in printing
In flexographic printing, Windmoeller & Hoelscher Corp., Lincoln, R.I., showed what it calls the first flexo press with infinitely variable repeats (in a range of 12-30 in.). W&H's Novoflex is a computerized, eight-color, mid-web (41-in.) press with digital AC vector drives instead of gears. Conventional gear drives limit repeats to a multiple of the gear-tooth size. The first machine goes to Mercury Plastics Inc. in City of Industry, Calif.
Du Pont Co.'s Cyrel Photopolymer & Electronic Materials division in Wilmington, Del., showed what it calls the world's first flexographic plate-making process that does not use solvents. The image is exposed conventionally using the company's Cyrel photopolymer plates. Then instead of washing unexposed polymer away with solvents, the excess polymer is heat-transferred 5-6 mils at a time onto a disposable nonwoven fabric. It takes 10 min and six passes to remove 0.003 in. of unexposed relief layers. The new technology is expected to be commercial by year's end.
It's curtains for coatings
Curtain coating, an old process for textile substrates, is a new way to apply pressure-sensitive adhesives to plastic film. On a pilot line in Switzerland, BMB (whose U.S. offices are in Green Bay, Wis.) is curtain coating film at 3000 ft/min, far faster and less expensively than gravure coating or slot dies, BMB says. The firm expects the first commercial application to be making peal-off labels.
Two new systems for measuring thickness and/or basis weight were introduced by SolveTech Inc., Claymont, Del. A new on-line capacitance gauge for coating weights can measure thin non-conductive coatings down to 2 micro-inches on thick non-conductive substrates. It uses two measurement heads, one before the coating is applied and cured and one after, and then subtracts the uncoated measurement from the coated one. Measuring thin coatings requires an unusually large (8-in. square) sensing area to reduce "noise."
SolveTech is developing the Double Back Scanner, reportedly the first noncontact capacitance gauge that can scan back and forth across the web. This allows the (24-in.-wide) capacitance gauge to measure wider webs.
For silicone coatings, Eltosch Torsten Schmidt GmbH in Germany (U.S. offices in Pine, Colo.), showed a new "environmentally friendly" inert uv-cure system. This was unveiled in January at an open house in Germany, running at 3000 ft/min. Inert uv curing also reduces the use of expensive photoinitiators and energy (as well as extractables and odors) with non-silicone coatings and improves the surface quality of cured film, Eltosch says. "Inerting," or eliminating oxygen, is usually done at the web surface, using excess photoinitiator in the coating to consume oxygen. Silicone acrylates, however, require extremely inert conditions with less than 50 ppm of oxygen, Eltosch says. The new system peels a surface layer of air from the web with two nozzles of nitrogen. Gas-tight quartz windows separate the inerting chamber from the uv lamps.
No static, no sweat
What's said to be the world's first two-bar electrostatic device was shown for the first time at CMM. Typical AC antistatic devices have outputs for positive and negative ions on one bar. Meech Static Eliminators Ltd. in the U.K. (U.S. offices at Meech USA, Richfield, Ohio) showed a steady-state DC device with positive output in one bar and negative in another. It can treat film faster than a one-bar system, Meech says. Meech has tested the bars at 3000 ft/min with 2-14 mil film and hasn't found a thickness limit. Independent controls let the two bars run singly or together.
Tantec Inc., Schaumburg, Ill., has brought to the U.S. a new high-density ionization system patented by Kasuga Denki Co. in Japan. This system is used to eliminate charges inside the film, not on its surface. It has an ion-attraction plate below the film and an AC static eliminator above, followed by two DC static eliminators.
For chill-roll stands, AWS Inc. (Applied Web Systems) in Elgin, Ill., launched a new, patented "anti-sweat" pack, which modulates tempered water into a chill roll if the web breaks. This keeps the roller from sweating while the web is being restored. Once the line is up and running, the roll switches back to normal cooling water. AWS also plans to show a new series of energy-efficient chillers at Plastics Fair Chicago in June.
Flyweight composite rolls
A new generation of lightweight composite rollers is made possible by a new super-high-modulus carbon fiber, called Dialead, from Mitsubishi Chemical Co. (U.S. offices in San Jose, Calif.). It has a modulus of 92 million psi, whereas 50-55 million psi was the previous limit for commercially available carbon fibers, according to roll maker ACPT Advanced Composite Products & Technology Inc., Huntington Beach, Calif. The super-stiff fiber originally cost $140/lb when only limited quantities were made for defense uses. But now an equivalent fiber is commercially available at less than a third of the former price.
ACPT introduced ultra-lightweight rollers based on the new fiber. Low roll weight reportedly pays off in extremely low inertia for webs requiring very low tension.
Also using the new fiber in composite rollers is Addax/Rexnord in Lincoln, Neb. Its new Advectus roller boasts higher critical speeds and less deflection. These rollers are being used in offset printing, collapsing frames on blown-film towers, and lay-on rolls for winders.
American Roller Co., Bannockburn, Ill., uses Dialead fiber in its new high-modulus Valcom composite rollers. In flexo printing, their extremely light weight and high rigidity reportedly mean less "bounce-back" and better image quality.
CMM was the first U.S. show for NANOsystems LLC of Germany, which recently opened U.S. offices in Gainesville, Ga. NANOsystems exhibited its line of "smart" CCD line-scan cameras for web inspection. "NANOdim" monitors web edge and center positions. "NANOtrace" inspects webs for pinholes, gels, specks and coating voids using a 2588-pixel CCD array. The NANOview camera combines these features and lets operators display and classify defects. Price is $30,000.
A new hand-held infrared thermal imager called DigiCam was shown by Ircon Inc., Niles, Ill. Its first application is taking "snapshots" of plastic film temperatures. It costs $15,000 and stores around 140 thermal images, which can then be downloaded to a computer and analyzed.