New Hot Melt Coating Laboratory Includes Turnkey Coating Station With Slot Die System From EDI

A new high-speed hot melt web coating laboratory at the Hendersonville, TN facility of ITW Dynatec includes a coating station that combines ITW Dynatec's melting and fluid delivery equipment with a slot die system from Extrusion Dies Industries, LLC (EDI), it was announced by EDI at CPP Expo (Booth 5549).

The "Proof of Process" lab enables companies to carry out application development or test run slot die coating before investing in an innovative turnkey coating station developed by ITW Dynatec and EDI.

The two companies introduced the turnkey station earlier this year, making available to operators of coating and laminating processes a single, fully integrated system whose performance is guaranteed by the partner companies. Since then, ITW Dynatec has installed the new laboratory, in which the slot die coating station is available for use with a new Catbridge Machinery web coating system that accommodates line speeds of up to 760 m/min. and coating widths up to 500 mm. The unit features an Allen-Bradley Controllogix™ controller, dual unwind and rewind with load cell display, and a wide tension range for low-weight substrates.

"The Proof of Process lab takes the guesswork out of investing in the turnkey hot melt coating station created by ITW Dynatec and EDI," said Dennis Paradise, EDI's vice president of sales and marketing. "The flexibility, high speed, and advanced control built into the lab enable manufacturers with a wide range of application requirements to discover how slot die coating can meet their needs and provide important advantages over other coating methods."

Turnkey Station Includes All Components for Melting, Delivering, and Applying Hot Melts

The turnkey hot melt coating station developed by EDI and ITW Dynatec can be designed to
apply virtually any hot melt material over the full range of viscosities and at temperatures from ambient to 500 deg. F. (260 deg. C.). Depending on equipment parameters and the type of application, the system can coat at speeds exceeding 2,000 feet (610 m) per minute on wide widths, and in coat weights down to 0.5 mil (0.013 mm) or less. Coat weight accuracy can be maintained within +/-1%.

The EDI portion of the coating station is a self-contained applicator unit called the Modular Coating System (MCS), which includes the slot die or coating head with adjustable lip opening and a robust, adjustable support for positioning the die lip with respect to the web; idler rolls; and a precision backing roll. These components are unitized within a steel frame whose crossbars maintain straightness during operation and adjustment.

The MCS incorporates mechanisms for fine adjustment and repeatability and includes a die innovation for coping with the gels, or solid particles, that occur in hot melts, noted Paradise. "Our die has a motorized rotating rod in the lip area that causes gels to pass through the narrow die lip opening rather than lodging there and generating streaks," Paradise said. "This makes it possible to achieve coat weights well below the conventional lower limit for hot melts of 1.0 mil (0.025 mm)."

A basic component provided by ITW Dynatec is the Dynamelt™ M-Series adhesive supply unit, or melter, which is a self-contained system for melting the adhesive and pumping it to the applicator. The system includes a PLC controller with user-friendly HIM interface. Various melt rates, hopper capacities, and pump rates are available. The Dynamelt features a patented Melt-On-Demand™ Hopper which melts only the adhesive required and virtually eliminates adhesive char. Another adhesive delivery method used with this turnkey system is Dynatec's DM55 DynaDrum™ Bulk Adhesive Melter. The DM55 Drum Unloader features inflatable seals which accommodate various drum diameters, and removable platen faces allowing for field retrofit.

ITW Dynatec's Gemini™ Automatic Hot Melt Hose delivers the adhesive from the melter to the applicator. The patented Gemini™ Automatic hose has dual heater and temperature sensors that keep the coating line up and running in the event of a hose failure. If a hose fault occurs Gemini switches to its back-up circuitry and an illuminated control box flashes, alerting the operator to change the hose during scheduled line-down time.

Slot dies must be custom-engineered to fit the application. "The manifold, or internal flow channel, of every die must be designed and precision machined to accommodate anticipated throughput and the unique rheology, or flow characteristics, of the adhesive," Paradise said. "The resulting control of flow behavior is one of the great advantages of slot die coating over conventional systems like spray or roll coating. Another is that slot dies are closed systems that maintain the hot melt fluid at a consistent temperature and distribute it uniformly across a precisely defined width."