Static charge accumulation on fluoropolymer release surfaces in heat-sealing, laminating, and web-handling equipment becomes a process defect when film wraps to chilled rollers, sparks discharge near solvent-bearing coatings, or airborne particulates adhere to charged webs. Saint-Gobain CHR SG56-06(R) Anti-Static Glass-PTFE Backing Silicone Adhesive Pressure Sensitive Tape is designed for such operations by replacing an unfilled PTFE-glass surface with a static-dissipative PTFE composite carried on woven fiberglass. The construction consists of a woven glass fabric carrier, a filled polytetrafluoroethylene coating on the release side, and a silicone pressure-sensitive adhesive on the bond side. The anti-static modification is associated with a black conductive-filler dispersion in the fluoropolymer layer; the R suffix identifies the static-dissipative variant within the manufacturer’s product family.

Nominal total thickness is 0.006 in (0.15 mm) when measured in accordance with ASTM D3652. The woven glass carrier provides tensile strength values near 150 lb/in (263 N/10 mm) and elongation at break below 5 % when tested under ASTM D3759/D3759M. Peel adhesion to stainless steel under ASTM D3330/D3330M Test Method A is commonly specified at 45 oz/in (49 N/100 mm) after dwell; initial tack is lower because silicone pressure-sensitive adhesives build bond through surface wetting and siloxane crosslink mobility rather than rapid cold-flow. Continuous service temperature extends from -73 °C to 260 °C, with intermittent use on heated bars acceptable where dwell time and thermal load do not exceed the adhesive’s oxidative stability limit.

Surface resistivity of the release side is maintained in the static-dissipative range, typically 1×10⁵ Ω/sq to 1×10⁹ Ω/sq when measured under ANSI/ESD STM11.11 and frequently below 1×10⁹ Ω/sq under ASTM D257 at 100 VDC. Unfilled PTFE-glass constructions can exceed 1×10¹⁵ Ω/sq under the same method. The conductive filler reduces surface resistance but also lowers dielectric strength relative to unfilled fluoropolymer-glass tapes; therefore the product is not specified as a primary electrical insulator.

Why Does Unfilled PTFE-Glass Tape Accumulate Charge in Low-Humidity Web Handling?

Unfilled PTFE occupies a strongly negative position in the triboelectric series. When a polymer web slides across an unfilled PTFE-glass release surface during indexing or continuous flow, electron transfer leaves the fluoropolymer surface with a charge that dissipates slowly across an insulating surface. At ambient relative humidity below 30 %, charge decay times can exceed the interval between film indexes on intermittent form-fill-seal equipment. The result is film tracking error, attraction of slitter dust, and discharge through grounded machine frames. The filled PTFE layer in SG56-06(R) shortens the charge decay pathway by forming a dissipative network at the surface while retaining sufficient fluoropolymer content for release function.

Static decay behavior measured under FTMS 101C Method 4046 from 5,000 V to 500 V is typically below 2 s for static-dissipative backing materials of this class. The result is process-relevant not only for web release but also for applications in which the tape is unwound manually in an electronics assembly area. Because the dissipative behavior is based on filler loading, slitting and abrasion can alter surface resistivity along the cut edge. Qualification tests should therefore sample at the tape edge and at the centerline when the tape is cut to widths below 25 mm.

In heat-seal and form-fill-seal operations, the tape is commonly applied to heated jaws, sealing bars, and rotary sealing drums where a non-stick surface must prevent polyethylene, polypropylene, or coextruded film from bonding to the tool. The glass fabric carrier restrains elongation under load, while the silicone adhesive bonds to metal bars and tolerates the dwell-temperature spikes encountered during seal cycles. The anti-static release side prevents the film from carrying residual charge into downstream slitting or weighing stations. On rotary seal drums operating above 100 m/min, charge accumulation on unfilled PTFE-glass surfaces can produce visible sparking under dark conditions; the dissipative surface of SG56-06(R) is intended to suppress that condition.

Surface Resistivity, Peel Adhesion, and Dielectric Test Matrix

Performance verification for this tape class requires separating surface electrical behavior from mechanical and adhesive properties. The following matrix summarizes applicable test methods and the expected distinction between the anti-static product and an unfilled PTFE-glass control.

The dielectric-strength reduction is a direct consequence of conductive-filler addition. In applications where the tape crosses an energized bus or serves as interlayer insulation, an unfilled PTFE-glass laminate may be required despite its charge-retention tendency. Conversely, where the tape functions only as a release surface and static-dissipative layer on a grounded metal tool, SG56-06(R) provides the preferred electrical behavior.

The silicone adhesive system is selected for high-temperature bond retention and clean removal from metal substrates. Silicone adhesives are not resistant to prolonged immersion in ketones, esters, aromatic hydrocarbons, chlorinated solvents, or aggressive alkaline cleaners. Short-cycle wiping with isopropanol or mild aqueous detergents can be used on the release side, but solvent penetration at exposed adhesive edges should be avoided. If aggressive cleaning agents contact the adhesive edge, tack loss and edge lifting can occur within 8 h to 24 h depending on solvent concentration and temperature.

When Silicone Adhesive Transfer Replaces Static Attraction as the Dominant Defect Mode

On corona-treated polyolefin webs and coated films, adhesive transfer can become the limiting defect if the tape is applied beyond the adhesive’s rated temperature or with insufficient cure dwell. Silicone pressure-sensitive adhesives do not chemically crosslink in the same manner as thermosetting acrylics; they retain viscoelastic flow at elevated temperature. Under sustained shear on vertical seal bars above 200 °C, edge migration can occur, leaving residue on the film. This failure is distinct from static-induced film tracking and must be diagnosed by measuring peel adhesion before and after thermal cycling under ASTM D3330/D3330M and by inspecting web surfaces under ultraviolet illumination for siloxane residue.

Bond strength to low-surface-energy substrates such as untreated polypropylene and PTFE itself is lower than bond strength to steel. The product should be qualified on the actual tool surface because surface roughness, oxide condition, and prior silicone contamination alter wetting. For silicone rubber-covered sealing bars, the silicone adhesive can develop overly aggressive tack due to compatibility with the substrate, making tape removal difficult. In such configurations, a thin stainless steel or polyimide shim layer under the tape may be required to preserve serviceability.

Storage conditions affect roll unwind behavior. The tape should be stored at 21 °C ± 3 °C and 50 % ± 10 % relative humidity in original packaging. Under high-humidity storage, moisture adsorbed on the glass fiber can create micro-blisters during initial heat-up on a seal bar. Pre-drying at 65 °C for 4 h may be applied before installation where rolls have been exposed to condensation-neutral cycles. The shelf life of silicone pressure-sensitive tapes in this class is commonly 12 months from date of manufacture when stored under the above conditions.

Slitting of the glass-PTFE laminate requires hardened blades because the glass fiber is abrasive. Dull blades produce frayed edges and can disrupt the conductive-filler network along the edge boundary, raising local surface resistivity. Slitting operations should use carbide or polycrystalline diamond blades with included angles between 22° and 30°, with blade coolant or dry slitting depending on line configuration. Edge inspection at 10× magnification should precede application in cleanroom or electronics assembly environments where liberated glass fibers or carbon-filled coating particles constitute contamination risks.

In wire-harness bundling and aerospace harness processing under IPC/WHMA-A-620, the tape may be selected where PTFE-backed glass tapes are already used for high-temperature bundling and the anti-static black backing reduces particle attraction. The silicone adhesive provides good compatibility with fluoropolymer wire insulations and silicone rubber jackets. The lower dielectric strength of the anti-static grade requires harness designers to verify that the tape is not used as a sole protective barrier over exposed conductors in areas subject to electrical clearance requirements.