Saint-Gobain CHR 2254-2 consists of a high-modulus skived polytetrafluoroethylene film backing and a cured silicone pressure-sensitive adhesive. The 2254 family designates the high-modulus PTFE film; the suffix -2 identifies the silicone adhesive system within the manufacturer’s CHR coding structure. The construction is supplied in slit rolls, traverse-wound spools, and die-cut formats for downstream converting. Lot-specific thickness and release-liner configurations are controlled under the manufacturer’s inspection documentation rather than a single universal value.

The backing is produced from high-modulus PTFE resin, which is skived and then wound under tension to create a film with lower elongation and higher tensile modulus than conventional skived PTFE film. This reduces elongation during tensioned web processing and improves dimensional stability in die-cut parts used as electrical insulating barriers, heat-seal release surfaces, and process-roll coverings. Typical production-scale applications include impulse heat sealers, L-bar sealers, RF welding dies, and wire-harness bundling where a low-friction, high-temperature release interface is required.

Silicone pressure-sensitive adhesive is selected for its wide continuous service temperature range and low-temperature tack. Published product-class data place silicone PSA on steel in the range of 20–40 oz/in when measured by ASTM D3330; specific adhesion values for the CHR 2254-2 configuration should be taken from the batch certificate. The adhesive is not a high-shear room-temperature PSA; continuous bearing loads above 150 °C require reinforced carrier support or mechanical clamping.

How Does High-Modulus PTFE Compare with Standard Skived PTFE Under Tensioned Web Loads?

Standard skived PTFE film undergoes progressive elongation during continuous web tension, which manifests as width loss and registration drift in converted parts. High-modulus PTFE stock for CHR 2254-2 exhibits reduced elongation at break under ASTM D3759 tensile loading. Typical high-modulus skived PTFE film in the 0.076 mm thickness class shows tensile strength near 45 lb/in and elongation at break near 150%, whereas standard skived PTFE of equal thickness may show elongation values above 250%. The difference is material-dependent; direct comparison requires that both films be tested at identical jaw separation, strain rate, and humidity because PTFE exhibits viscoelastic response at room temperature.

Viscoelastic creep of PTFE at room temperature is non-negligible; a tensile stress of 10–15 MPa can produce measurable creep in standard PTFE at 23 °C over 24 h under tensile creep testing such as ASTM D2990. High-modulus PTFE is processed to reduce cold flow; however, the tape backing remains thermoplastic and should not be subjected to continuous tension exceeding 25% of its short-time tensile strength for dimensional-critical applications. In heat-seal packaging lines, this difference reduces tape deformation when the tape is tensioned over a sealing bar. Dimensional stability minimizes creep in extended production runs, so the release surface remains flat and free of adhesive bleed-through.

During slitting and die-cutting, high-modulus PTFE film dissipates less heat than filled PTFE and can generate edge burrs when dull rotary dies are used. Converters processing CHR 2254-2 on high-speed rotary die lines with anvil clearances below 0.025 mm report edge nicking and adhesive stringing if the silicone layer is not cooled below 4 °C during cutting. Liquid nitrogen or chilled anvil rolls are used to achieve clean cuts on parts with narrow tie bars or sharp radii. Published data for this specific configuration is limited; converting trials are used to establish die pressure and anvil temperature for a given part geometry.

For electrical insulation applications, the PTFE backing provides a dielectric barrier between conductors and metal chassis surfaces. Dielectric strength values for high-modulus PTFE film are typically reported in the range 6,000–8,000 V for a 0.127 mm total tape construction under ASTM D149 short-time testing. However, wrapped-wire harness assemblies require verification of edge effect and layer overlap; voltage endurance under partial discharge conditions is not equivalent to short-time breakdown. The tape is therefore applied as a supplemental insulation layer, not as a primary insulation system under IEC 60664-1.

In process-roll covering, the tape is wrapped with a silicone adhesive bond to metal rolls; the PTFE surface provides release against adhesive coatings and reduced friction. Roll covering with high-modulus PTFE tape is generally limited to non-continuous duty below 260 °C; sustained operation above this temperature degrades the silicone adhesive while the PTFE backing itself does not melt until 327 °C. The operational gap between adhesive service limit and backing melting point is a critical processing boundary. In RF welding and heat-sealing bar applications, surface release effectiveness is evaluated by contact angle and coefficient of friction. PTFE film typically exhibits a kinetic coefficient of friction below 0.1 against polished steel at 23 °C under ASTM D1894. The high-modulus film maintains this low friction while reducing stick-slip in tensioned wrap applications.

Electrical and Mechanical Property Benchmarks

The table below consolidates typical values reported for CHR 2254-2 and the corresponding test methods. Values are representative, not batch limits; a certificate of analysis controls lot-specific compliance.

Bond strength on steel is measured after a controlled dwell following lamination. Production lines achieve higher and more uniform adhesion when the metal surface is cleaned with isopropanol or methyl ethyl ketone, abraded or chemically etched to a surface energy above 38 mN/m according to ASTM D2578 wetting tension tests, and then dried at 65 °C for 10–15 s before tape application. Relative humidity above 60% can reduce initial tack by forming a moisture film on hydrophilic surfaces; pre-drying is required in such environments. The silicone PSA is not recommended for bonding to untreated polyethylene, polypropylene, or silicone-release-coated films without corona or plasma treatment.

Specific permeation and chemical compatibility values for the adhesive layer in CHR 2254-2 are not always published; when exposed to aggressive aromatic hydrocarbons, initial testing on a coexisting lot is required because silicone PSA can swell and lose shear strength. PTFE film backings may comply with FDA 21 CFR 177.1550 for perfluorocarbon resins when the specific resin and manufacturing conditions meet the regulation; adhesive compliance is a separate requirement. Users must verify direct food-contact status with the manufacturer’s written statement before use in FDA regulated applications.

When Silicone Adhesive Is Selected Over Acrylic or Rubber Pressure-Sensitive Systems

Silicone PSA on CHR 2254-2 is chosen where the temperature range extends beyond acrylic PSA limits and where low-temperature tack is required. Acrylic PSAs may provide higher room-temperature shear adhesion but generally are limited to 120–150 °C continuous exposure; rubber PSAs are typically limited below 100 °C. Silicone PSA remains functional from −73 °C to 260 °C, although high-temperature shear strength is low; external mechanical fixturing is recommended above 150 °C. Comparative peel data by ASTM D3330 and static shear by ASTM D3654 show that silicone systems trade room-temperature ultimate peel for broader environmental tolerance.

The PTFE backing differentiates CHR 2254-2 from polyester or polyimide tapes. Polyester backings are lower cost but are limited to 150 °C continuous exposure and exhibit higher surface energy. Polyimide tapes withstand high temperature but do not provide the same low release surface or chemical inertness. Glass-cloth PTFE tapes provide higher tensile strength and abrasion resistance but are thicker and less conformable; CHR 2254-2 is selected when a homogeneous non-woven PTFE film is needed for electrical flatness or for a continuous release contact.

Silicone PSAs may evolve low-molecular-weight siloxanes at elevated temperatures; in cleanroom or optical assemblies, volatile siloxane contamination can be a disadvantage. Acrylic or polyimide adhesives are sometimes selected for low-outgassing applications under ASTM E595. CHR 2254-2 is therefore evaluated against outgassing specifications before use in precision optical or semiconductor environments. Customers should request current regulatory declarations for REACH Regulation (EC) No 1907/2006 and RoHS Directive 2011/65/EU before qualifying the material for restricted-application programs.

Shelf life and storage conditions affect silicone PSA properties. Rolls should be stored at 21–27 °C and 40–60% relative humidity in original packaging. Exposure to direct sunlight or ozone is not required for PTFE film stability but can degrade liner and adhesive edges. Extended storage beyond the manufacturer-specified shelf life may require re-testing of adhesion to steel under ASTM D3330 before production release.

For high-temperature heat sealing, the tape should be wrapped with 50–70% overlap on the sealing bar to prevent the adhesive line from contacting the product directly. The PTFE surface must be kept free of carbonized product residues; silicone oil contamination reduces release performance and is removed with solvent wiping rather than abrasive cleaning. This material is not recommended for continuous immersion in strong caustic or for direct exposure to fluorine gas at elevated temperature; PTFE decomposition above 400 °C liberates toxic species.