Saint-Gobain CHR 23816 is a single-faced pressure-sensitive tape constructed from a woven E-glass fabric backing impregnated and overcoated with a cured silicone elastomer, then coated on one side with a crosslinked silicone pressure-sensitive adhesive. The product is supplied in log rolls with a release-treated interleaf and is specified where high-temperature electrical insulation, resistance to cut-through, and adhesion to low-surface-energy substrates must be combined. Because the glass fabric distributes tensile stress in both machine and transverse directions, the tape remains dimensionally stable under coil-winding and roll-to-roll converting tension. The adhesive is a supported silicone PSA rather than a heat-cured adhesive; bond formation is generated by applied pressure and dwell time, not by oven cure. This places CHR 23816 within the class of pressure-sensitive insulating tapes evaluated under ASTM D1000 and IEC 60454-1:1998, rather than heat-reactive laminating adhesives.

How Does CHR 23816 Differ from Acrylic and Polyimide PSA Tape Styles?

At 25 °C, the silicone PSA on CHR 23816 displays lower initial tack than a typical crosslinked acrylic transfer tape. Peel adhesion to polished stainless steel under ASTM D3330 for glass-silicone PSA tape commonly falls between 4.5 N/25 mm and 7.0 N/25 mm, whereas high-tack acrylic systems may exceed 12 N/25 mm. Lower initial peel is not a processing defect; it reflects slower room-temperature flow and lower surface energy of the silicone network. The relevant performance shift appears after thermal ageing. Above 150 °C, the silicone adhesive retains peel and shear because siloxane crosslinks resist oxidative chain scission, while acrylic ester adhesives soften and lose cohesive strength. Polyimide film with silicone adhesive shares the high-temperature adhesive chemistry but uses a backing thickness of 0.025–0.08 mm. That thin film conforms to sharp slot geometries and fine radii, but it lacks the cut-through resistance and mechanical reinforcement of the glass-silicone backing. Polyester film with acrylic adhesive offers optical clarity and high initial adhesion, but its continuous service ceiling is typically 105 °C, which excludes it from bake cycles above 180 °C.

The comparative profile shows that CHR 23816 is selected when mechanical robustness and high-temperature endurance outweigh the need for very thin gauge or optical clarity. Published data for exact lot-specific values should be retrieved from the manufacturer’s certificate of conformance; the figures above represent class-level ranges commonly cited for silicone-glass pressure-sensitive tape products.

Glass-Silicone Backing Construction and Silicone Adhesive Transfer Behaviour

The glass fabric in CHR 23816 is a woven E-glass structure treated with silane coupling chemistry before silicone impregnation. The silicone elastomer overcoat fills the interstices and creates a uniform surface for adhesive coating. Total caliper variation of ±0.02 mm can occur across a log width, and this variation affects stack height in laminated slot insulation and calender nip pressure in converting operations. Adhesive transfer behaviour is controlled by the balance between cohesive strength and interfacial adhesion. When rolls are stored above 30 °C, adhesive can partially transfer to the release interleaf; conditioning at 21 °C ± 2 °C for 24 h usually restores normal interfacial behaviour. Bulk adhesive transfer to the release liner indicates cohesive failure and requires quarantine of the affected roll section.

Solvent resistance is an operational boundary. Short-term contact with aliphatic hydrocarbons such as heptane is generally acceptable, while continuous immersion in toluene, xylene, methyl ethyl ketone, or ester-based cleaning fluids causes swelling and loss of peel adhesion. The glass backing is degraded by hot concentrated alkali and hydrofluoric acid, and these media should be excluded from the process environment. The tape is compatible with many transformer oils and silicone fluids, although published data for long-term oil immersion of this specific construction is limited and should be confirmed by application-specific testing.

Surface preparation influences adhesion more than adhesive chemistry in many applications. On copper, aluminium, and steel, wipe cleaning with isopropanol or heptane followed by drying at 60 °C for 10 min improves initial wet-out. On silicone-coated release liners or silicone rubber surfaces, the substrate must be free of migrated silicone oil, because excess low-molecular-weight siloxane acts as a weak boundary layer. For highly fluorinated surfaces, plasma or corona pretreatment may be necessary; without surface activation, even silicone PSA builds only limited peel strength.

Without a header, the following application set covers the largest production uses. In traction motor coil manufacturing, CHR 23816 is applied as interlayer insulation or banding tape over magnet wire and ground-wall insulation. The high warp-direction tensile strength under ASTM D3759 accommodates automatic taping heads, but elongation at break is typically below 6%. Tension control must therefore be set below the yield point of the woven glass to prevent edge curl and adhesive ooze before varnish cure. In powder coating masking, the tape is exposed to bake cycles between 180 °C and 220 °C for 15–30 min. The silicone adhesive resists carbonization and clean release is generally obtained after the cycle, but the tape edge must be firmly pressed to prevent powder ingress under the edge. Sharp profiles below approximately 3 mm radius may require a second tape layer because the thicker glass backing cannot conform without lifting.

When Thermal Exposure Exceeds 180 °C in Masking and Coil Applications

At thermal exposures above 180 °C, the glass-silicone backing remains electrically and mechanically stable, but the carrier’s thermal expansion and the adhesive’s viscoelastic response can change bond geometry. In coil insulation, the tape may be vacuum-pressure impregnated with epoxy or polyester resin and cured at 150 °C; the silicone surface is hydrophobic, so resin wetting must be evaluated against the insulation system specification. Electrical acceptance is commonly verified by ASTM D149 dielectric breakdown and ASTM D1000 tape tests. A single layer of this tape class is typically rated for 3.0–5.0 kV breakdown, but motor hipot acceptance tests require a safety factor determined by the relevant equipment standard. The glass-silicone combination may be assigned to a Class H insulation system when used with compatible varnishes and slot liners, but system recognition must be obtained under UL 510 or IEC 60085 for the complete insulation system.

Roll-to-roll converting of silicone-coated release liners uses CHR 23816 as a flying-splice tape because the silicone adhesive bonds to the low-energy silicone surface without aggressive solvent etching. The splice must remain flat under web tension up to 1.5 N/mm and pass through drying zones at 120–150 °C. A dwell time of 24 h at room temperature after splicing increases peel to near maximum; immediate splicing at line start may show reduced peel until the adhesive has wet out the liner surface. Compared with PTFE-coated glass cloth tapes, CHR 23816 has a higher coefficient of friction against moving web guides because the exposed backing is not a nonstick release surface. CHR 23816 is intended as an adhesive bonding tape, not as a release or anti-friction tape.

Glass fabrics adsorb moisture at the exposed edge; the silicone overcoat reduces but does not eliminate water uptake. For critical electrical applications, rolls should be conditioned at 20 °C ± 2 °C and 50 ± 10 % RH for 24 h before application. Storage above 80 % RH may increase dielectric loss and reduce breakdown strength, particularly in partial-discharge-sensitive insulation systems.

The operational limits for CHR 23816 are defined by chemical exposure, mechanical tension, and high-humidity storage rather than by maximum thermal endurance alone. For applications involving continuous immersion in aromatic solvents, contact with hot concentrated alkalis, or repeated flexing over radii below approximately 3 mm, alternative backing and adhesive combinations should be selected.