Saint-Gobain CHR SG15-05(R) High Performance Glass-PTFE Backing Silicone Adhesive Pressure Sensitive Tape is supplied as a composite pressure-sensitive tape in which a woven glass fabric is coated with polytetrafluoroethylene (PTFE) to form the backing, and a high-temperature silicone pressure-sensitive adhesive is applied to one face. The glass reinforcement limits elongation and tear propagation during slitting and in cyclic mechanical loads, while the PTFE layer provides a low-surface-energy release face, high-temperature resistance, and electrical insulation. The (R) suffix identifies a roll or liner configuration that must be confirmed against lot-specific packaging specifications because regional Saint-Gobain CHR datasheets use the suffix differently. Published data for the exact SG15-05(R) configuration is limited in the public domain; values cited below derive from the product-family technical bulletin and from standard test methods applicable to coated glass-cloth pressure-sensitive tapes.

The backing is not skived PTFE film but a PTFE-coated woven glass fabric. Nominal total thickness is commonly referenced in the 0.18 mm (0.007 in) range, measured according to ASTM D3652, with a backing thickness near 0.13 mm (0.005 in) and an adhesive contribution that varies with coating pass and liner. The silicone adhesive retains tack below −73 °C and resists oxidative degradation above 200 °C for short dwell periods. Peel strength after thermal aging is a function of substrate, dwell time, and applied load; no single value should be used for process qualification.

Construction of the Composite Backing and Silicone Adhesive Interface

The glass fabric is selected to balance conformability and tensile strength. During manufacture, the fabric is coated or impregnated with aqueous PTFE dispersion in multiple passes to fill the weave and build the required release surface. The silicone pressure-sensitive adhesive may be applied to the fabric side or to a chemically etched PTFE surface; anchorage relies primarily on mechanical interlocking into the glass weave rather than on covalent bonding to the PTFE matrix. This interface explains why the tape releases cleanly from the non-adhesive face but can leave silicone transfer on copper or polyimide substrates if thermally overstressed or if shear loads exceed the adhesive’s cohesive limit.

The PTFE dispersion used to coat the glass fabric contains colloidal polytetrafluoroethylene and a wetting surfactant that is pyrolytically removed during sintering. Incomplete sintering leaves residual surfactant, which can appear as discoloration at sustained temperatures and can reduce dielectric strength. The high-performance variant is typically processed to reduce non-PTFE residues. Incoming tape should be visually inspected for pinholes, weave strike-through, and adhesive voids. Pinholes are critical in electrical insulation because partial discharge can initiate at these discontinuities.

The silicone adhesive is typically a crosslinked dimethyl silicone system formulated for high-temperature pressure-sensitive applications. Continuous service temperature is often cited at 260 °C, but shear strength declines above 220 °C. Peel adhesion to stainless steel measured by ASTM D3330 Test Method A is generally in the 4 N/25 mm to 6 N/25 mm range depending on dwell and substrate finish. The woven glass backing restricts elongation at break to a range near 5 % or less under ASTM D3759, which is lower than unfilled skived PTFE.

Because PTFE is chemically inert, the silicone adhesive is usually anchored to the glass-rich face or to a sodium-etched PTFE surface. Mechanical interlocking with the glass weave provides shear resistance; the smooth PTFE face remains the release surface. If the adhesive is applied over an untreated PTFE face without etching, anchorage is poor and the adhesive may transfer during cyclic thermal loading. The (R) configuration is sometimes reverse-wound to present a specific face at the outer diameter; this affects automated applicators and must be verified before line setup.

The composite backing is not resistant to hydrofluoric acid, strong hot alkali, or molten alkali metals; these agents attack the glass phase. The PTFE surface is not suitable for bonding or printing unless treated by sodium etching or plasma, and silicone adhesives are not recommended where high-friction or high-shear mechanical loads are applied at temperatures above 220 °C.

What Distinguishes SG15-05(R) From Unfilled PTFE Skived Film Tapes?

Unfilled skived PTFE tape offers high elongation and smooth conformability; the glass-reinforced SG15-05(R) is specified where cutting, tension, or repeated jaw cycling produces tearing or cold flow in skived films. The following comparative data are targets from standard test methods and product-family literature, not lot-release limits.

The higher breaking strength of SG15-05(R) reduces necking and tear growth on seal bars, but it also lowers conformity to small radii. Skived PTFE remains preferable for smooth, high-dielectric-strength wraps where tensile load is minimal and continuous surface contact is required.

Die cutting and slitting differ between SG15-05(R) and skived film. Skived PTFE elongates under die-kiss pressure and can smear onto cutting edges; SG15-05(R) cuts more cleanly but generates glass-fiber debris if die clearance is not controlled. Laser cutting is possible but leaves a charred edge and should be validated with an extracted-ion chromatography or outgassing test if the part is used in an electronics enclosure.

Compared with CHR products that use acrylic or rubber adhesives, SG15-05(R) trades initial tack and room-temperature shear for high-temperature stability and resistance to oxidative yellowing. Acrylic-adhesive glass tapes have better shear at 20 °C to 100 °C but lose adhesion above 150 °C. Rubber-adhesive tapes offer high initial grab but degrade above 90 °C and are unsuitable for heat-seal service. Silicone PSAs also maintain flexibility below −60 °C, while acrylic systems can stiffen. These differences direct product substitution only after a tape’s full operating envelope is known.

On a rotary heat-seal jaw line for polyolefin over-wrap film, the tape is applied to the sealing bar. The silicone adhesive must withstand cyclic surface temperatures of 180 °C to 220 °C and intermittent excursions to 260 °C. The glass fabric prevents necking and creep at the jaw radius. If the jaw surface is not degreased before application, adhesive transfer can occur within 24 h of cycling. Field results from production-scale sealing lines indicate that dwell time, jaw pressure, and film gauge have a larger effect on tape life than the absolute temperature setpoint. Published data for this specific configuration is limited; qualification should include a 48 h thermal cycling trial at the actual seal temperature and pressure.

After tape replacement, a bedding-in period of several hundred cycles is sometimes required before the silicone adhesive reaches full anchorage on the metal jaw. Operators often run the seal line at reduced speed during this period; full shear strength is reached only after the adhesive has wet out the micro-roughness of the metal surface. This production practice is not a substitute for surface preparation but reduces premature edge lift at part changeover.

When Heat-Seal Bar Temperatures Exceed 200 °C

The PTFE phase does not melt at standard heat-seal conditions; its continuous service limit is generally cited as 260 °C, with decomposition onset above 400 °C. The silicone adhesive is the limiting layer. At temperatures above 220 °C, peel strength drops and cohesive failure may occur if the tape is under shear or cyclic tension. At 260 °C, continuous exposure is feasible only with low load and no shear. Above 260 °C, the adhesive can embrittle and the glass-PTFE backing can begin to discolor. The tape should not be used in applications where silicone outgassing or adhesive transfer onto optical surfaces is unacceptable.

At temperatures above 200 °C, oxidation of the silicone adhesive can produce low-molecular-weight siloxanes. In applications such as medical device assembly or optical assembly, these condensable species may cause contamination. The tape is therefore not selected for cleanroom or optical-bonding environments unless the outgassing profile has been tested using ASTM E595 or an equivalent system. For thermal management applications, the total mass loss and collected volatile condensable material should be below the line-specific threshold. Published data for this specific configuration is limited; users should not substitute generic silicone-adhesive outgassing data without a lot-specific measurement.

Electrical breakdown values measured by ASTM D149 are useful for incoming control, but end-use dielectric performance depends on wrap overlap, varnish impregnation, and mechanical damage. For coated glass-cloth tapes, breakdown voltage falls after creasing or when the weave is distorted under high winding tension. Electrical insulation qualification should include the actual creased-and-aged condition rather than flat-sheet data alone.

Adhesive Transfer, Surface Preparation, and Storage Boundaries

Application to metal surfaces requires removal of oils, particulates, and silicone mold-release residues. A final wipe with isopropanol or another suitable solvent should be followed by complete evaporation before tape application. The minimum application temperature is typically 10 °C to avoid condensation and to maintain adhesive tack; warm tape and substrate improve wet-out. Silicone pressure-sensitive adhesives have low surface energy and do not bond well to untreated polyethylene, polypropylene, or fluoropolymer surfaces.

Aluminum and stainless steel substrates respond well to acid or alkaline cleaning followed by solvent wipe. Abrasion with a fine non-woven pad can increase mechanical interlocking but may leave debris that reduces adhesive contact. Silicone pressure-sensitive adhesives do not require a primer on clean aluminum or steel; however, copper and copper alloys may require passivation or priming when used at high temperature because oxidation products at the interface can weaken the adhesive bond. Polyimide and polyester films can be used as carrier substrates, but plasticizers or low-molecular-weight species may migrate into the adhesive and alter peel adhesion.

Application at more than 80 % relative humidity can trap moisture at the adhesive-substrate interface and reduce initial tack. If the tape is applied to a cold substrate, condensation can form and later cause lifting. The substrate surface temperature should be at least 3 °C above the dew point, and in refrigerated packaging lines this may require local heating of the seal bar before tape application.

Rolled inventory should be stored in original packaging at 0 °C to 27 °C and relative humidity below 70 %. Storage life is generally 24 months from date of manufacture when stored under these conditions. Exposure to ozone, direct sunlight, or high humidity can reduce tack and cause edge fraying. The tape should not be creased or subjected to compressive load during storage, because the glass fabric can take a permanent set.

Chemical incompatibilities include strong hot alkali, hydrofluoric acid, molten sodium, and fluorine gas. The glass fabric is attacked by these agents even though the PTFE surface is resistant. The tape is not suitable for liquid oxygen or high-oxygen service unless the entire system has been reviewed for oxygen compatibility.

In powder-coating masking, glass-PTFE tapes are used as high-temperature masking strips on racks and hooks. The tape survives short exposures to curing ovens at 200 °C to 230 °C and releases powder build-up from the PTFE face. However, the silicone adhesive may leave a residue if the tape is exposed to oven cycles longer than 30 min or if the part is subsequently washed with aggressive solvent. The glass backing resists tearing when the tape is stripped away from masked edges. Users should confirm that the coating line’s oven air velocity does not lift the tape edge; edge lifting is a processing failure caused more by aerodynamic load than by adhesive temperature limits.

Incoming inspection and qualification use the following standard matrix. The status column must be confirmed with lot-specific documentation because compliance depends on regional supply and liner configuration.

Coil-winding and slot-liner applications use the tape where a thin, tear-resistant insulating barrier must survive Class H thermal excursions. The tape is wrapped over magnet wire and placed between coil layers. The glass fabric withstands winding tension better than polymeric films, and the silicone adhesive holds the tape in place during varnish impregnation. Electrical breakdown values measured with ASTM D149 are maintained after thermal aging at 200 °C for short durations; however, varnish compatibility must be tested because solvent-borne polyester or epoxy varnishes can extract low-molecular-weight silicone species and reduce dielectric performance. Users should confirm that the varnish cure schedule does not exceed the silicone adhesive’s shear limit. Published data for this specific configuration is limited.