Laminator Static Control Kelly Robinson, PE, PhD Electrostatic Answers
Agenda 1. Motivation a. Lamination provides unique features - excellent barrier properties, mechanical strength. b. Static sealed within the laminate cannot be neutralized. 2. Charge Control Strategy a. Prevent charge from accumulating on both surfaces. b. Neutralize charge at the source. 3. Analysis: Lamination Line a. Static dissipaters are located through the line (not just near the winder). b. 13 Static bars and 3 passive devices are needed. 4. Summary 2 / 17
Motivation Static dissipater Neutralizing ions Static sealed within laminate Web #2 Web #1 Travel The neutralizing ions from the static dissipater deposit on the insulating surface and cannot penetrate to the static sealed within the laminate. 3 / 17
Charge Control Strategy Charged web surface Static bar ions Machine frame Web Static bar Electric field Static charge Neutral web surface The electric field from the static on the web surface draws ions from the static dissipater. 4 / 17
Charge Control Strategy Static bar ions Machine frame Static bar Web surface with negative static Electric field Web surface with positive static Web With static one on surface and an equal amount of opposite polarity static on the other surface, no ions are drawn to the web. Jargon: Polar charge 5 / 17
Lamination Line Dryer Unwind #2 Lam Wind Unwind #1 Corona Treat Coat Roll Handling Roll Handling The static control system for this lamination line includes static dissipaters in each operation. 6 / 17
Unwinders Unwinding roll Over unwind SB1 SB2 1 Tension SB3 control nip 5 3 4 Exiting web 2 Under unwind Static is neutralized on both sides of the web exiting the unwinding roll. Static bars SB1 & SB2 and idler rollers 1 5 are in fixed positions. SB3 neutralizes static from the nip. 7 / 17
Corona Treater 1 3 4 Corona treater 2 SB4 The high level of static on the treated surface must be neutralized prior to the first roller that touches the back side. 8 / 17
Pre-nip Ionization Neutral side of web Ionization region Web Charged side of web Static charges Electric filed Partially neutralized static charge Exiting web Pre-nip ionization at rollers that touch the charged side of the web help neutralize static. Note that the electric field does not cross the web. 9 / 17
Pre-nip Ionization Neutral side of web Web Electric field Static charges from ionization Exiting web Charged side of web Static charges Ionization region This roller that touches the neutral side of a charged web deposits static on the neutral side by pre-nip ionization. Note that the electric field crosses the web. 10 / 17
Corona Treater 1 3 4 Corona treater 2 SB4 The charged surface touches with roller 3 (OK). The neutral surface touches roller 4 (BAD). Neutralize static before it reaches roller 4! 11 / 17
Coater Pressure roller Exiting web SB5 SB6 Coating roller Static bar SB5 is a safety net and SB6 prevents ignitions should the coater run dry. 12 / 17
Dryer Dryer Exiting web SB7 Ionizing cords or tinsels Ionizing cords on the backside prevent ignitions in the event of a fan failure. SB7 neutralizes static from backside contact. 13 / 17
Laminator Coated web Polymer roller SB8 Entering web #2 Metal roller Exiting laminate Static bar 8 neutralizes charge from the polymer lamination roller. Note that there are no static dissipaters on the webs prior to lamination. 14 / 17
Winder Tension control nip SB9 Winding roll Entering web Lay-on roller SB10 Static bar 9 neutralizes charge from the polymer nip roller. SB10 neutralizes static from the lay-on roller and also limits the potential of the winding roll. 15 / 17
Summary 1. Neutralize static at the source. 2. Neutralize static before the neutral surface of the web touches a roller. 3. Polar charge - one surface has positive charge and the other has negative charge. 4. Static dissipaters are unable to neutralize polar charge. As a consequence, polar charge persists through the process to the winding roll. 5. Charge control in a lamination line is important to prevent static from being seal within the laminate. 6. The static control system neutralizes static during normal operation and provides fail-safe neutralization for the solvent rich coater and potentially solvent rich dryer. 7. A static bar is needed to neutralize static from a winder lay-on roller. This final static bar also reduces the electric potential of the winding roll caused by residual levels of static on the web. 16 / 17
Questions?! Kelly Robinson, PE, PhD IEEE Fellow, Patent Agent Owner, Electrostatic Answers 17 / 17