Saint-Gobain CHR SG35-10(R) is a reinforced pressure-sensitive tape consisting of a woven fibreglass backing that is impregnated and coated with polytetrafluoroethylene, commonly abbreviated PTFE, and combined with a silicone pressure-sensitive adhesive. The model designation reflects a 0.010 in (0.25 mm) nominal backing thickness, while the (R) suffix identifies roll-stock format and liner configuration. Total caliper with adhesive is typically specified in the 0.012 in to 0.014 in (0.30 mm to 0.36 mm) range, with slit widths available from narrow die-cut strips to 18 in rolls. The product is produced on master logs and converted to roll lengths commonly specified at 36 yd (33 m) on 3 in (76 mm) fibre cores, though custom lengths are sourced from converters.

The glass-PTFE backing is supplied with one side modified for bonding and the opposite side retaining fluoropolymer release behaviour. This asymmetry prevents the adhesive from transferring to heated sealing faces while allowing the backing to function as a non-stick barrier. The silicone adhesive layer is designed for continuous exposure from approximately −73 °C to 260 °C. Peel adhesion to stainless steel is evaluated under ASTM D3330/D3330M, tensile strength and elongation under ASTM D3759/D3759M, and total thickness under ASTM D3652/D3652M. Values shown on published product literature are nominal; lot-specific certificates of conformance should be used where the tape is assigned to a defined process control plan.

What separates the silicone adhesive system from acrylic and rubber pressure-sensitive alternatives on this tape?

Silicone pressure-sensitive adhesive differs from acrylic and rubber systems primarily in thermal stability, low-temperature flexibility, and response to sustained shear at elevated temperatures. Acrylic transfer adhesives on glass-PTFE backings are generally limited to continuous surface temperatures below 150 °C to 180 °C. Rubber-resin systems are frequently restricted to 105 °C to 120 °C because of oxidative softening and adhesive transfer. The silicone adhesive used on SG35-10(R) maintains measurable room-temperature peel and elevated-temperature shear above 200 °C, although the absolute shear load-bearing value declines significantly with temperature.

On constant-heat seal bars operating between 190 °C and 240 °C, acrylic adhesives can soften at the adhesive-backing interface and leave residue on jaw surfaces. Silicone adhesive reduces this transfer mode, but it requires higher installation pressure or longer dwell to develop wet-out on low-energy substrates. When the tape is applied to a heated jaw under contact pressure of 0.3 MPa to 0.5 MPa, the adhesive undergoes flow into the surface texture of the metal, creating mechanical anchorage. At the low-temperature end, the silicone system retains flexibility at −73 °C, whereas acrylic layers can crack during unwind or liner removal. The trade-off is that silicone adhesives generally present lower initial room-temperature tack than high-peel acrylic tapes.

For electrical insulation and wire-harness wrapping, the silicone adhesive contributes broader service temperature margins than rubber-based tapes, especially in engine-compartment or coil-form applications where transient temperatures reach 200 °C. The glass-PTFE backing also prevents the adhesive from wicking into fibre bundles after prolonged thermal soak. Users should nevertheless specify the intended substrate because silicone adhesives are not universally compatible with all liners and surfaces. Polyethylene, untreated PTFE, and some silicone-coated release papers require lower unwind tension to avoid cohesive splitting of the adhesive film.

The product differs from acrylic-coated PTFE glass tapes in predictable process terms. Acrylic versions provide higher initial tack and are typically easier to apply in ambient packaging operations. Silicone versions provide superior resistance to heat-seal jaw contamination and can remain in place for longer cycle counts on heated bars. The boundary condition is adhesive shear. At 220 °C, silicone PSA shear strength is materially lower than at 25 °C, and rope-edged edges may lift if the tape is placed under continuous machine-direction tension.

In heating tunnels and radiant thermal exposure zones, the silicone adhesive is less prone to colour shift and embrittlement than acrylic or rubber adhesives, but the PTFE surface must not be abraded with steel tools during installation. Scratches reduce release performance and create local film build-up points on hot-melt adhesive lines. Where the tape is applied over polished chrome rollers, the surface should be cleaned with 2-propanol or another low-residue solvent and dried before the liner is removed. Residual silicone oil from prior cleaning operations can prevent anchorage and is a documented cause of peeling at roller edges.

In rotary heat-sealing operations on horizontal form-fill-seal machines with heated flat jaws, the tape is installed as a release cover to prevent polyethylene or polypropylene melt from fusing to the jaw face. The woven fibreglass carrier limits elongation and neck-in during tensioned installation, keeping the tape aligned across the jaw. The silicone adhesive allows repositioning within a short open time, but repeated lifts reduce final adhesion. Liner removal should be performed at a low angle and constant speed to avoid transferring adhesive to the backside of the tape. Once installed, the tape should be inspected after each shift for edge lift, charring, or surface wear. A common rejection threshold is peel adhesion below 25 oz/in (6.8 N/25 mm) when tested after thermal aging against a clean stainless-steel panel.

Glass-PTFE Backing Reinforcement, Thermal Aging, and Dielectric Breakdown Thresholds

The fibreglass reinforcement creates a mechanically different structure from unsupported skived PTFE film. Skived PTFE exhibits significant cold flow under compressive load. At contact pressures above 0.2 MPa on heated rollers, unsupported PTFE can thin, spread, and tear at the edge, causing release failure and film build-up. SG35-10(R) transfers the tensile stress into the glass fabric, limiting elongation at break to approximately 3% to 5% as measured by ASTM D3759/D3759M. Commercial skived PTFE films routinely elongate 150% or more before break. That difference is significant when tension is applied during installation on rollers with profiled flanges or chamfered edges.

The PTFE surface contributes a low coefficient of friction against polished steel, commonly reported below 0.10 dynamic as measured by ASTM D1894. The silicone adhesive side is not a release surface. If the liner is removed and the adhesive layer contacts the PTFE surface during roll set-up, fibre-tearing can occur because the bond between adhesive and backing is stronger than the interlayer release. This is a processing distinction from double-faced adhesive transfer tapes.

Electrical performance is evaluated by ASTM D149 for dielectric breakdown voltage and by ASTM D257 for surface and volume resistivity where documentation is required for coil and cable insulation. Glass-PTFE tapes in this thickness class commonly withstand 3,000 V to 6,000 V breakdown voltage depending on adhesive caliper, backing uniformity, and environmental conditioning. Measured values decrease after exposure to high humidity because fibre-reinforced backings can absorb moisture at cut edges. Pre-drying at 60 °C for 24 h is recommended when rolls have been stored at relative humidity above 60% and dielectric strength is critical. For process control, a maintaining lot average above 3,500 V is often required for motor slot liners and interlayer insulation in wound coils.

The tabulated values are nominal ranges for the 0.010 in glass-PTFE silicone adhesive class and should not be used as acceptance limits without reviewing the manufacturer’s current certificate of conformance. Property retention after thermal cycling at 200 °C for 1,000 h is commonly evaluated for release-liner delamination, adhesive discolouration, and backside release degradation. Published data for this specific configuration is limited; therefore, qualification should be performed on the exact slit width and liner grade used in production.

The fluoropolymer surface is chemically resistant to most solvents, acid solutions, and hydraulic fluids. It is not resistant to molten alkali metals or gaseous fluorine-containing etchants at elevated temperature, which attack the PTFE chain. The silicone adhesive is also incompatible with sulfur-cured EPDM surfaces containing migratory curatives. If the tape is used as a release cover over a chlorinated elastomer roller, adhesive anchorage should be tested under actual nip pressure and temperature for a minimum of 72 h.

When SG35-10(R) Replaces Skived PTFE Covering on Continuous Heat-Seal Rollers

Continuous web lines that convert from unsupported skived PTFE covering to SG35-10(R) observe a different mechanical response at nip stations. Unsupported skived PTFE conforms to the roller surface, but under sustained tension it creeps in the machine direction and accumulates film growth at the roller edges. SG35-10(R) constrains this creep through the woven glass carrier. The change reduces registration drift in release bands used on hot-melt slot-die lamination lines. However, the tape is not a direct substitute where high elongation is deliberately used to wrap compound-curved surfaces without wrinkles. The glass fabric resists deformation, and installation on small-radius roller ends may require edge scoring or overlapping tabs.

On rollers operating between 200 °C and 260 °C, the silicone adhesive retains shear strength longer than acrylic systems, but the backing should not be exposed to temperatures above 260 °C for prolonged periods. PTFE degradation accelerates above 280 °C to 300 °C, and silicone adhesive embrittlement occurs near the same range. Hot-spotting under buried thermocouples or band heaters can exceed the average roller temperature, producing local adhesive failure that appears as edge creep or bubbling. When used in infrared ovens, the tape should be installed only after the roller surface temperature has been mapped to confirm that all locations remain below the continuous-use limit.

The release side of the tape prevents hot-melt adhesive build-up, but release performance is not permanent. Exposure to high-shear abrasion from metal doctor blades or scraper knives removes the PTFE layer and exposes the fibreglass. Once the glass fibres are visible, the tape must be replaced. Visual inspection under 10× magnification identifies fibreglass breakout at the wear surface. For roller-wrap jobs on pressure-sensitive adhesive coating lines, periodic surface energy checks using a 32 dyne/cm test fluid can be used to detect loss of fluoropolymer release; a wetted streak on the PTFE side indicates contamination or wear and requires cleaning or replacement.

Slitting and die cutting of SG35-10(R) require attention to adhesive flow. High-speed rotary shear slitting can produce adhesive smear on cut edges if blade temperature rises above 80 °C. Crush-cut systems should be used only with hardened anvils and controlled interference, because the glass backing is abrasive and reduces blade service life relative to polyester film tapes. For clean edge quality, a rotary shear blade with a hardness above 62 HRC and a line speed below 100 m/min is typical. Slit rolls should be wound at constant tension below 5 N/25 mm to prevent telescoping and adhesive bleed at the roll face.

Wire-harness and coil-wrapping applications use the tape as an interlayer insulation wrap. The tape is commonly applied with a 50% overlap under winding tension of 10 N to 30 N. The glass reinforcement resists cut-through from enamel-coated copper wire and maintains layer geometry during varnish impregnation. The silicone adhesive accepts moderate movement of the wire bundle during forming without losing bond, provided the wrap is not repeatedly flexed before cure. The PTFE surface also reduces the risk of coated wire sticking to the outer wrap during thermal cycling.

The product is generally supplied with RoHS and REACH regulatory documentation when requested, but compliance must be confirmed for each manufacturing lot. The fluoropolymer resin component may be associated with 21 CFR 177.1550 in food-contact constructions; this does not automatically make the finished pressure-sensitive tape suitable for direct food contact. Additional migration testing and substrate-specific approval are required. For electrical tape recognition, the relevant document is UL 510, but recognition applies to specific widths, backings, and constructions. SG35-10(R) should not be substituted into a UL-listed application without verifying that the exact style and thickness are covered by the file.

Storage conditions influence converting behaviour. Rolls should be retained in polyethylene packaging at 10 °C to 32 °C and below 60% relative humidity. The release liner can become dimensionally unstable in high humidity, causing curl in slit strips. Cold-weather shipment requires a conditioning period at ambient temperature before slitting because silicone adhesive stiffens below −20 °C and may crack under rapid unwind. Acrylic tapes are generally more tolerant of low-temperature slitting, but the silicone product returns to full adhesive performance after warming. The glass-PTFE backing itself remains dimensionally stable through the conditioning period.

Roll covering on seamers and sealing bars requires periodic replacement because the silicone adhesive becomes progressively brittle after repeated thermal cycles. Edge lift, charring, or measured peel strength below 25 oz/in (6.8 N/25 mm) after aging indicates the end of the service interval. The tape should not be incinerated or laser-cut without local exhaust because PTFE decomposition products can be generated at high temperatures.