Saint-Gobain CHR 2915-10 Glass Cloth Backing Silicone Adhesive Pressure Sensitive Tape is a single-sided, high-temperature electrical insulation tape in which a woven electrical-grade glass cloth carrier is coated with a cured silicone pressure-sensitive adhesive. The product code suffix “-10” corresponds to a nominal total thickness of 0.254 mm (0.010 in) within the CHR 2915 series. The tape is supplied as a self-wound log roll; standard widths range from 6.35 mm (0.25 in) to 914 mm (36 in), and the standard roll length is 32.9 m (36 yd). Because the backing is woven fabric rather than cast film, edge tear resistance and conformability over slot edges and lead break-outs are higher than for film-backed pressure-sensitive tapes. The silicone adhesive extends the upper continuous operating temperature to 200 °C, with intermittent exposure tolerance to 260 °C for short dwell cycles. Thermal failure is governed by oxidative embrittlement of the silicone mass and possible degradation of the glass sizing rather than by melting of the carrier. Published data for this specific configuration is limited to the manufacturer’s technical data sheet; values reproduced here are representative of the CHR 2915 series and should be confirmed against the batch certificate of analysis.

Within the CHR 2915 series, the 0.010 in (0.254 mm) build differs from CHR 2915-5 primarily in dielectric and mechanical reserve. The heavier glass cloth raises machine-direction tensile strength to approximately 30.7 N/mm (175 lb/in) and dielectric breakdown to approximately 4,000 V when tested in air according to ASTM D149-20. CHR 2915-5, at nominally 0.127 mm (0.005 in), is preferred where space claim is restricted or where lower bending stiffness is required; it provides proportionally lower voltage withstand and tensile strength. Selection between the two is therefore determined by slot fill, voltage margin, and abrasion load, not solely by adhesive performance.

What separates silicone adhesive glass cloth from polyimide and acrylic PSA alternatives?

The silicone pressure-sensitive adhesive on CHR 2915-10 retains a measurable fraction of room-temperature peel strength after short-dwell exposure at 200 °C, whereas conventional acrylic PSAs generally lose adhesion and become brittle above 120–150 °C after repeated cycling. This distinction is critical in motor coil and transformer lead-out wrapping where the tape must survive baking or impregnation without lifting at the overlap. Polyimide-film silicone tapes offer higher dielectric strength per unit thickness and a smoother surface, but their thin film is more easily punctured by sharp core steel edges. Glass cloth gives CHR 2915-10 higher tensile strength and abrasion resistance at equal total thickness, with better conformability over irregular coil surfaces. Rubber-adhesive glass cloth tapes may provide higher room-temperature tack, but they are not suitable for continuous service above 105 °C. Silicone adhesive also releases more consistently from copper and steel after thermal exposure, although initial tack on low-surface-energy substrates is lower than rubber or acrylic systems.

Design data for CHR 2915-10 are summarized in the property matrix below.

The adhesion value is a 180° peel measurement on stainless steel at 23 °C and 50% relative humidity after a 24 h dwell. Tensile and elongation values are machine-direction data; cross-machine values may be lower because of fabric anisotropy. The single-layer dielectric breakdown value should not be used as a design withstand for wrapped coils. Partial discharge, creepage distance, and layer-to-layer voltage grading dominate in high-voltage insulation systems.

On production-scale motor coil taping lines, CHR 2915-10 is applied as a containment wrap before vacuum-pressure impregnation. Taping heads are typically equipped with closed-loop tension spindles set at 2–4 N per 25 mm width. If unwind tension exceeds 4 N, the glass weave can neck down and the adhesive can flow out at the slit edge. Application is normally half-lap or butt-lap, with overlap held to 0.5–1.0 mm on straight sections. The wrapped coil enters an epoxy or unsaturated polyester VPI process at 60–80 °C and 3–5 bar; during resin gelation, the tape functions as a mechanical constraint, not as the primary groundwall insulation. Successful processing requires that underlying mica, enamel, or steel surfaces be free of silicone oil, plasticizer, and amine-based release agents. Low-molecular-weight amines can alter the cure state of the silicone pressure-sensitive adhesive at the bond line and reduce tack; this is a frequently observed field failure mode when amine-containing mold release agents are used upstream.

In high-voltage coil end-winding consolidation, CHR 2915-10 is used as an overwrap over mica tape layers. The dielectric grading system relies on the mica groundwall; the glass cloth tape contributes mechanical restraint and moderate dielectric strength but is not a substitute for the mica insulation. The single-layer dielectric strength is measured in air; when multiple half-lap layers are wound over an end-winding, withstand voltage does not scale linearly because of entrapped air pockets and field enhancement at each overlap edge.

When the substrate is silicone rubber or a low-surface-energy thermoplastic, surface preparation controls the bond line

Peel adhesion of CHR 2915-10 to stainless steel is typically 2.7 N/10 mm (25 oz/in) when measured by ASTM D3330. On low-surface-energy substrates below 30 mN/m, such as untreated polypropylene or silicone rubber, initial peel strength can fall below 1.0 N/10 mm unless the surface is prepared. Wiping with isopropyl alcohol or naphtha removes plasticizer bloom but does not increase surface energy; corona or plasma treatment to 40–50 mN/m is required for thermoplastic films. For silicone rubber, the silicone adhesive can build bond strength over time, but residual silicone oils from processed gaskets must be removed by wiping with a 70:30 isopropanol/water mixture and drying at 60 °C for 10 min. On copper, the alkalinity of certain oxide passivation baths can attack the silicone adhesive during long dwell times; the tape should not be left as a temporary wrap on bare copper for more than 30 days at elevated humidity.

Slitting, unwind tension, and taping-head parameters observed on production winding lines

Converting CHR 2915-10 from master rolls to slit rolls requires shear-cut equipment rather than razor slitting when edge quality is critical. The glass fibers are abrasive; tungsten carbide or ceramic-edged shear blades are specified to hold a burr level below 0.025 mm per edge. Rotary slitting speeds of 50–100 m/min are used for woven glass cloth silicone tapes, with web tension held between 3–5 N per 25 mm width. Higher tension causes the fabric to distort and creates a curved tape that will not lay flat on a coil slot. On taping heads with a 25 mm wide roll, the unwind brake should be set to 2–4 N to maintain fiber alignment. Published production-scale data for this specific configuration is limited; the stated parameters are representative of silicone adhesive woven glass cloth behavior and should be confirmed by a converting trial on the target slitter.

In powder coating operations, CHR 2915-10 is used to mask threaded holes, bearing seats, and electrical contact areas through cure ovens operating at 180–220 °C for 15–30 min. A single cure cycle typically leaves no carbonized adhesive residue when the tape is removed below 80 °C; removal at elevated temperature increases cohesive failure risk and can transfer silicone residue. Multiple cycles above 200 °C progressively harden the adhesive and shorten clean removal life. In plasma spray booths where surface temperatures can exceed 260 °C, the glass cloth may survive short exposure, but adhesive degradation and fuming limit the product to temporary masking rather than continuous operation.

Compared with PTFE-coated glass cloth tapes, CHR 2915-10 does not provide a low-friction release surface for sliding contact or mold release. The silicone adhesive is the exposed functional layer in the assembled form, whereas PTFE-coated glass cloth is commonly used as a facing or separator. Selection therefore depends on whether the application demands adhesion to the substrate or release from process media. In heat-sealing jaw wraps, a non-adhesive PTFE-coated glass cloth is generally preferred; CHR 2915-10 is used where the tape must remain adhered to the coil, bar, or harness under vibration.

This product is not recommended for immersion in toluene, xylene, chlorinated solvents, or gasoline, because the silicone mass swells and loses peel strength. If solvent wiping is required before application, use isopropyl alcohol or naphtha in a ventilated area and allow the surface to dry completely. Storage should be maintained at 20–25 °C and 45–55% relative humidity with the roll suspended on its core; prolonged side pressure or high humidity can cause the glass cloth to absorb moisture and reduce dielectric margin before application.