State of the Art Static Control for Flexible Packaging

• Presented by: Kelly Robinson, PE, PhD Electrostatic Answers

K. Robinson Static Control for Flexible Packaging 1/49 Speaker Introduction

Kelly Robinson, PE, PhD, Owner – Electrostatic Answers LLC [email protected] 585-425-8158 • www.ElectrostaticAnswers.com • Business Owner - Founded Electrostatic Answers, an engineering consulting company dedicated to eliminating injury and waste from static electricity. • Industrial Experience – working over 35 years solving static problems in web conveyance and solvent handling manufacturing operations. • Award Winning Engineer Institute of Electrical and Electronics Engineers (IEEE) Fellow cited for “contributions to electrostatic performance of mfg. processes” US Nat’l Fire Protection Assoc. (NFPA), Chair – Committee on Static Electricity Assoc. Int’l Metallizers Ctrs & Lamintors (AIMCAL) - Technical Consultant • Inventor with 15 US patents. • Associate Editor for the Journal of Electrostatics, a leading peer reviewed journal (Elsevier publication) • Contributing Editor, Paper Film & Foil Converter, author of “Static Beat” column on static control.

K. Robinson Static Control for Flexible Packaging 2/49 Agenda

1.Introduction – Static control is important 2.Design Principles 3.Measurements – Static Survey 4.Best Practice Static Control 5.Manage Static Performance 6.Summary

K. Robinson Static Control for Flexible Packaging 3/49 1. Controlling static is important!

2. Prevent shocks.

1. Eliminate ignitions.

3. Minimize deposition of airborne contaminates

K. Robinson Static Control for Flexible Packaging 4/49 1. Controlling static is important!

5. Prevent static problems Image courtesy in customer applications of (sheet sticking, process jams). PSA Label

Release liner

4. Prevent spark damage to sensitive coatings such as silicone release liners. (Sparks damage the coatings allowing PSA labels to stick to liners).

K. Robinson Static Control for Flexible Packaging 5/49 Agenda

1.Introduction – Static control is important 2.Design Principles – SOTA Static Control 3.Measurements – Static Survey 4.Best Practice Static Control 5.Manage Static Performance 6.Summary

K. Robinson Static Control for Flexible Packaging 6/49 2. Design Principles Think “Risk, Threat, and Countermeasure” (FMEA – Failure Modes & Effects Analysis)

Static THREAT THREAT (static charge) RISK (static charge) (flammable Fault mixture) Fault

A “threat” penetrates to a “risk” only when there are 2 simultaneous The system effectively faults; one in the outer layer and shields a “risk” from a “threat” when there is a single fault. one in the inner layer.

A4 Protect risk areas with “2-layer,” fault tolerant static control systems

K. Robinson Static Control for Flexible Packaging 7/49 Question 1: With “fault tolerant” design, are critical functions maintained even when any single system components fails?

K. Robinson Static Control for Flexible Packaging 8/49 Answers 1: YES!

With a “fault tolerant” design, critical functions are maintained when any single system component fails.

K. Robinson Static Control for Flexible Packaging 9/49 Agenda

1.Introduction – Static control is important 2.Design Principles 3.Measurements  Electrostatic Fieldmeter  Static Survey 4.Best Practice Static Control 5.Manage Static Performance 6.Summary

K. Robinson Static Control for Flexible Packaging 10/49 2.1 Electrostatic Fieldmeter

Carl Friedrich Gauss was a German mathematician and scientist who contributed significantly to many fields, including number theory, statistics, analysis, differential geometry, geodesy, electrostatics, astronomy and optics. http://en.wikipedia.org/wiki/Carl_Friedrich_Gauss Area A E σ Gaussian S,TOP Surface +++++ +++++ Vo l u me V σ S,BOTTOM Johann Carl Friedrich Gauss Born: 30 April 1777 Died: 23 February 1855 Gauss’ Law http://upload.wikimedia.org/wikipedia /commons/3/33/Bendixen_-_ Electric flux penetrating Carl_Friedrich_Gau%C3%9F%2C_1828.jp the surface is proportional g to the charge enclosed. A3

K. Robinson Static Control for Flexible Packaging 11/49 2.1 Electrostatic Fieldmeter (Work horse instrument for solving static problems!)

Electrostatic KV measures the fieldmeter E=− 5 electric field in from net charge Charged surface Static charge –– – – – Web ––– –

Charged surface Note: Fieldmeter readings may be taken from either side of the web. A3

K. Robinson Static Control for Flexible Packaging 12/49 Question 2: Do electrostatic fieldmeters respond only to the charges on one surface or to the total number of charges on the web?

K. Robinson Static Control for Flexible Packaging 13/49 Answers 2:

TOTAL NUMNBER OF CHARGES!

Electrostatic fieldmeters respond to all of the charges inside the control volume, which is the total number of charges on the web.

K. Robinson Static Control for Flexible Packaging 14/49 2.1 Electrostatic Fieldmeter (Work horse instrument for solving static problems!)

Monroe 282IS KV/in Simco FMX-004 3M718 KV/in KV/in

Meech 983v2 Fraser EX715 KV/(15cm) KV/(10cm)

Monroe 257D KV/cm Note: The operator must be grounded for reliable readings. Wear static dissipative shoes, touch grounded metal, or use a grounding cable.

K. Robinson Static Control for Flexible Packaging 15/49 Question 3: When using fieldmeters from different vendors, are the displayed static levels the same number?

K. Robinson Static Control for Flexible Packaging 16/49 Answers 3: NO!

Static meters from different vendors use different units for electric field so the displayed readings must be converted to consistent units.

K. Robinson Static Control for Flexible Packaging 17/49 2.1 Measurements Reliable Static Measurements An electrostatic fieldmeters is the work horse for diagnosing and solving static problems.

Static Reading E “GeeZE” Rules charges for fieldmeter on film Radius = 2G readings: surface Static 1. Ground the meter operator. Gap 2. Zero the + + + G + + + fieldmeter. Insulating film + + + + + 3. Empty the such as PET, BOPP, PTFE “measurement Measurement sphere.” spherical

In your “mind’s eye,” draw a dot the web below the fieldmeter. The dot becomes the center of a sphere that expands to a radius of 2G. For reliable readings, the “measurement sphere” must be empty (except for the meter and your hand).

K. Robinson Static Control for Flexible Packaging 18/49 Agenda

1.Introduction – Static control is important 2.Design Principles 3.Measurements  Electrostatic Fieldmeter  Static Survey 4.Best Practice Static Control 5.Manage Static Performance 6.Summary

K. Robinson Static Control for Flexible Packaging 19/49 3.2 Measurements – Static Survey

Dryer 1. Take fieldmeter reading Dry Dry Out on each accessible Guider In - web span, - unwinding roll(s), and 1st coat - the winding roll(s). Chill contact Out CT CT SB Out Inspect Coat Out In Chill SD contact CT SB Dance Chill Guide Out Out Out Dance Coat Out Out Dancer Wind Corona treater Span Wind Unwind Inspect Dancer

Dance Coat In In Nip Contact Inspect Nip roller Wind Unwind Unwind Coater Out SB roll roll span

2. At each location, record 3. Plot readings on a “Stoplight Chart” maximum, average, and to document static performance. minimum readings.

K. Robinson Static Control for Flexible Packaging 20/49 3.2 Measurements – Static Survey

Electrostatic Fieldmeter MeasurementsDate 4/23/2019 Measurement # Location Min Max Average Range Shift Static surveys 1Unwind Roll -7.5 -2.5 -5.0 5.0 #N/A might have 2Unwind-Span -1.3 0.0 -0.6 1.3 #N/A 40 or 50 3 Dance In -2.0 -0.5 -1.3 1.5 -0.6 4Dance Out -3.0 -1.3 -2.1 1.8 -0.9 measurements. 5Corona Trt Out 12.5 22.5 17.5 10.0 19.6 6Corona Trt SB Out -1.0 0.0 -0.5 1.0 -18.0 7Coat-In -1.8 -1.0 -1.4 0.8 -0.9 8 Coat-Out -1.0 0.5 -0.3 1.5 1.1 Let’s plot 9Dry-In -1.5 0.0 -0.8 1.5 -0.5 10 Dry-Out -16.0 -6.5 -11.3 9.5 -10.5 the readings 11 Guide-Out -21.0 -11.5 -16.3 9.5 -5.0 to analyze 12 Coat Contact-Out 10.0 15.0 12.5 5.0 28.8 the data 13 Chill Out 15.0 20.0 17.5 5.0 5.0 14 Inspect In 2.5 5.0 3.8 2.5 -13.8 15 Inspect Out 1.3 3.8 2.5 2.5 -1.3 16 Nip In 0.0 2.5 1.3 2.5 -1.3 17 Nip Out -10.0 -7.5 -8.8 2.5 -10.0 18 Nip SB Out -1.3 0.0 -0.6 1.3 8.1 19 Dance Out -3.8 -2.5 -3.1 1.3 -2.5 20 Wind Span -4.5 -3.0 -3.8 1.5 -0.6 21 Wind Roll -10.0-5.0-7.55.0#N/A

K. Robinson Static Control for Flexible Packaging 21/49 3.2 Static Survey – Stop Light Chart 25

20 High Red Zone; ±15 KV/in < E

15 Static Nip roller dissipator added charge. 10 Moderate Yellow Zone; ±5 < E < ±15 KV/in OK Static dissipator OK 5 Low Green Zone; E < ±5 KV/in 0

-5 Dryer , guider, -10 Corona Treater idler touching coating added + charge. & chill roller all SB OK added charge. -15 Electrostatic Fieldmeter Reading [KV/in] -20

-25

1. Static Performance: Keep reading in the “Green Zone.” K. Robinson Static Control for Flexible Packaging 22/49 Question 4: What is the common “industry standard” fieldmeter reading for low static?

K. Robinson Static Control for Flexible Packaging 23/49 Answers 4: The electric field E should not exceed ±5 KV/in or ±2 KV/cm

K. Robinson Static Control for Flexible Packaging 24/49 3.2 Measurements – Source Chart

Dance Coat In In Nip Contact Inspect Nip roller Wind Unwind Unwind Coater Out SB roll roll span

2. At each location, record 3. Plot changes in readings on a “Source Chart” maximum, average, and to identify sources of static charging. minimum readings.

K. Robinson Static Control for Flexible Packaging 25/49 3. Static Survey – Source Chart (Shifts) 40 Static dissipator Shifts > ±5 KV/in indicate needed at 1st roller significant charging source. 30 that touched Corona treater coated surface. added + charge 20 Static dissipator neutralized 10 Chill roller – static from static dissipator nip roller OK 0

-10

Static bar Nip roller -20 dissipated Dissipators needed deposited + + charge from at Dryer exit charge. Change Change betwen Fieldmeter Measurements [KV/in] corona treater and guider exit -30

K. Robinson Static Control for Flexible Packaging 26/49 3.2 Common Static Charging Sources

Charge Source (μC/m2) NOTE: We don’t need Lamination Nips ±250 a static dissipator Corona Treaters ±50 after every roller! Unwinding Rolls ±20 Sparks occur when Polymer Nip Rollers ±15 charge > ~ ±5 μC/m2 Tacky Web Cleaning Rollers ±15 Drive / Pull Rollers ±15 Neutralize static at each charging source Heated / Cooled Rollers ±15 that deposits Spreader / Bowed Rollers ±10 μ 2 ±5 C/m or more. Dryer / Oven Idler Rollers ±10 Web Guides ±5 Registration Compensation Rollers ±4 Dancer Rollers ±2 Metal Idler Rollers ±0.2

K. Robinson Static Control for Flexible Packaging 27/49 3.2 Static Survey – Spark Chart

Charging source + + + typically deposit relatively uniform charge across the web. + + +

+ + +

Web motion E

3 [KV/cm]

Time [Sec] 0

With relatively uniform static charges on the web, an electrostatic fieldmeter measuring these charges will have a relatively steady reading

K. Robinson Static Control for Flexible Packaging 28/49 3.2 Static Survey – Spark Chart

Non-uniform

+ + + charge Sparking can cause causes − cut sheets non-uniform to stick charge + + + together.

− + + + − −

Web motion

3 [KV/cm]

Time [Sec] 0

Static sparks deposit spots of opposite polarity charge on the web. Our electrostatic fieldmeter will have highly variable reads. Some readings may have alternating polarity

K. Robinson Static Control for Flexible Packaging 29/49 3.2 Static Survey – Spark Chart (Ranges)

12 Ranges > ~8 KV/in indicate sparking may have occurred. Sparking likely occurred exiting 10 dryer and 1st roller Sparking likely that touched the occurred exiting freshly dried coating. corona treater. 8

4 Average Range

2 Fieldmeter Measurement Range [KV/in]

K. Robinson Static Control for Flexible Packaging 30/49 Question 5: Why does “sparking” increase the range of electrostatic fieldmeter readings?

K. Robinson Static Control for Flexible Packaging 31/49 Answers 5: Sparks are like “miniature static dissipators.” They deposit spots of opposite charges on the web causing the fieldmeter readings to vary widely, sometimes even changing polarity.

K. Robinson Static Control for Flexible Packaging 32/49 Agenda

1.Introduction – Static control is important 2.Design Principles 3.Measurements  Electrostatic Fieldmeter  Static Survey 4.Best Practice Static Control 5.Manage Static Performance 6.Summary

K. Robinson Static Control for Flexible Packaging 33/49 4. SOTA Static Control – Coaters

Exiting Pressure web roller

SB1 SB2

SB1 is a failsafe to insure SB2 prevents ignition that the web entering should the coater runs dry the coating nip is neutral. or when splices fails.

Coating roller

K. Robinson Static Control for Flexible Packaging 34/49 4. SOTA Static Control – Roller Resistivity

100 1×10+11 Ω-m Relative dielectric constant κ R = 4.0

50 5×10+10 Ω-m

2×10+10 Ω-m

+10 Ω 20 1×10 -m

5×10+9 Ω-m

10 2×10+9 Ω-m

1×10+9 Ω-m Roller Diameter (inches) Diameter Roller 4

5×10+8 Ω-m

2×10+8 Ω-m 1 0 100 200 300 400 500 600 700 800 900 1000 Web Speed (ft / min) K. Robinson Static Control for Flexible Packaging 35/49 Question 5: Why must the “backing roller” or “pressure roller” in a solvent gravure coater be “static dissipative?”

K. Robinson Static Control for Flexible Packaging 36/49 Answers 5: TO PREVENT SPARKS!

The “backing roller” or “pressure roller” charges by touching the web. We must dissipate these charges to prevent a spark in the solvent area.

K. Robinson Static Control for Flexible Packaging 37/49 4. Best Practice Static Control – Corona Treater Source: Static on treated surface from corona treater.

+ SB13

+ Install a static dissipator Corona (powered static bar or passive dissipator): treater - on the web span exiting the corona treater, - facing the treated web surface, and - prior to the first roller that touches the treated surface.

K. Robinson Static Control for Flexible Packaging 38/49 4. SOTA Static Control – Unwinding Roll Outside Unwinding surface nip of web

Exiting 1 5 web Roll 4 3

Inside Outside surface surface of web

To talk about unwinding rolls, we need some common language.

K. Robinson Static Control for Flexible Packaging 39/49 4. SOTA Static Control – Unwinding Roll

Unwinding nip Over unwind Exiting + + 1 5 web – 4 – 3 Unwinding roll 2 Inside Outside surface surface

At the unwinding nip, the inside surface of the web peels from the outside surface of the unwinding roll.

K. Robinson Static Control for Flexible Packaging 40/49 4. SOTA Static Control – Unwinding Roll

Unwinding KV ESPAN =~ 0 nip cm

KV Exiting = −10 – – – – EROLL cm + + 1 5 + web – – – + + – – 4 3 – + – + – – 2 –

In steady state, the outside surface of the roll carries negative charge and the exiting web carries balanced charge.

K. Robinson Static Control for Flexible Packaging 41/49 4. SOTA Static Control – Unwinding Roll

Over unwind Exiting + + 1 5 web – Unwinding 4 – + 3 roll SB1 SB2 2

Two static bars SB1 and SB2 are needed to neutralize static on both sides of the web from tribocharging.

K. Robinson Static Control for Flexible Packaging 42/49 4. SOTA Static Control – Unwinding Roll

Over unwind Exiting web + + 1 5 – Unwinding 4 3 roll – + SB1 SB2 2

Under unwind Both static bars SB1 and SB2 are needed to neutralize static on both sides of the web from tribocharging for either unwind direction.

The exiting web is nearly charge-free.

K. Robinson Static Control for Flexible Packaging 43/49 Question 6: Why are two static dissipators needed to control static on an unwinding roll?”

K. Robinson Static Control for Flexible Packaging 44/49 Answers 6: Charges separated at the unwinding nip are on two web surfaces; (1) the top surface and (2) the bottom surface.

A single static dissipator can neutralize static on only one web surface.

K. Robinson Static Control for Flexible Packaging 45/49 4. SOTA Static Control – Winding Rolls

Tension control SB2 neutralizes static nip Metal from the lay-on roller roller and limits the potential nip of the winding roll. Polymer + roller Lay-on nip roller Winding Entering SB1 roll web

‒ Static bar SB1 neutralizes charge SB2 from the polymer nip roller.

K. Robinson Static Control for Flexible Packaging 46/49 Agenda

1.Introduction – Static control is important 2.Design Principles 3.Measurements  Electrostatic Fieldmeter  Static Survey 4.Best Practice Static Control 5.Manage Static Performance 6.Summary

K. Robinson Static Control for Flexible Packaging 47/49 5. Manage Static – Recommendations

# Description R1 When static is important, devote ~2% of scheduled work hours to static control. R2 Train operators annually (or on an appropriate schedule) on static electricity awareness. R3 Install each static dissipator to have good neutralization efficiency. R4 Energize active static bars only when the line is running. R5 Make a checklist identifying the location of each static dissipator (photo?). R6 Visually inspect each static dissipator periodically (weekly?) to ensure that each is fit-for-use. By “fit-for-use,” I mean 3 things: 1. The dissipator is in place and properly spaced. 2. The pins of static bars are clean. Passive dissipators are in good physical condition. 3. Power is applied to active bars. R7 Measure periodically (quarterly?) the neutralization efficiency of each static dissipator. R8 Periodically inspect (monthly?) rollers to verify that they are fit-for-use. By this, I mean 4 things. 1. The roller surfaces are clean. 2. The roller bearings are functioning properly. 3. The rollers are aligned properly. 4. The web path is free of debris that might touch the moving web. R9 Audit the static levels on incoming rolls. R10 Audit the static levels on finished rolls. R11 Perform a static survey to qualify lines for service after major maintenance operations. R12 Perform a static survey as part of Management of Change.

K. Robinson Static Control for Flexible Packaging 48 48/49 6. Summary

Thank-you! QUESTIONS ? 1.Introduction – Static control is important 2.Design Principles 3.Measurements  Electrostatic Fieldmeter  Static Survey 4.Best Practice Static Control 5.Manage Static Performance 6.Summary

K. Robinson Static Control for Flexible Packaging 49/49