Saint-Gobain CHR 2302-3R UHMW Film Backing Acrylic Adhesive Pressure Sensitive Tape

Saint-Gobain CHR 2302-3R consists of a low-friction ultra-high-molecular-weight polyethylene film backing carrying a pressure-sensitive acrylic adhesive on one face. The UHMW film belongs to a class of polyolefins distinguished by average molecular weight between 3.0 × 10⁶ g/mol and 6.0 × 10⁶ g/mol, a molecular weight range that separates UHMW from conventional high-density polyethylene and contributes to its resistance to sliding wear and moisture uptake. The -3R suffix is a manufacturer thickness-grade code associated with a nominal backing thickness of 0.003 in (0.076 mm), and the total caliper of the tape without release liner is commonly cited near 0.005 in (0.127 mm). Lot-specific thickness and slitting tolerances should be confirmed against the Saint-Gobain technical data sheet for the exact roll format. The backing typically exhibits water absorption below 0.01 % after 24 h immersion per ASTM D570 and a linear coefficient of thermal expansion in the range of 1.3 × 10^-4 K^-1 to 1.7 × 10^-4 K^-1.

Typical uses for this construction include wear strips, guide-rail covers, chute liners, and low-friction surface patches on packaging, paper-converting, and light assembly machinery. The acrylic adhesive is selected to provide a balance of peel strength and oxidative resistance, while the UHMW film supplies abrasion resistance and a low-friction contact face. The product is supplied in slit roll form; roll width and length vary with distributor stock formats, and edge condition may influence long-term bond life on high-speed packaging rails.

Engineering Properties of the UHMW Backing

Published data for UHMW films of this class report tensile strength per ASTM D882 commonly between 15 MPa and 30 MPa in the machine direction, with elongation at break often exceeding 200 %. The measured dynamic coefficient of friction against polished 304 stainless steel per ASTM D1894 generally falls from 0.10 to 0.22. Static friction values may be slightly higher. The backing is nonporous and resists most dilute acids, alkalis, and polar solvents at ambient temperature, but oxidizing acids and some aromatic hydrocarbons at elevated temperature can degrade the polyolefin surface. Abrasion resistance of UHMW in tape form is conventionally evaluated by relative Taber wear or ASTM D4060; published product-specific values for CHR 2302-3R in thin-film form are less widely available than those for compression-molded UHMW sheet, so comparative wear ranking on actual equipment is often necessary.

UHMW creep behavior under sustained normal load is a measurable design limitation. The film can flow over time under concentrated compressive stress, particularly at temperatures above 60 °C. Installation on flat sliding surfaces distributes load more uniformly than point-loaded wear strips. For long-term static bearing loads above approximately 1.0 MPa, the backing should be evaluated for cold-flow in the exact service geometry, because thickness loss at contact points can change tracking and product registration.

What Limits the Continuous Service Temperature of CHR 2302-3R?

The continuous service ceiling is controlled by the acrylic adhesive rather than the UHMW film. The adhesive layer typically retains peel strength through 82 °C (180 °F) and may withstand short-term excursions at 100 °C (212 °F) for intermittent cleaning or low-load exposure. The UHMW backing itself has a crystalline melting range near 130 °C to 136 °C, but mechanical properties soften well before melting. At low temperature, the tape can be used at -40 °C (-40 °F) if the acrylic has been allowed to build full peel strength before chilling. Thermal cycling does not cross-link the acrylic, but repeated cycles above 60 °C may accelerate oxidative embrittlement at exposed tape edges.

For washdown or steam-cleaning cycles above 82 °C, a silicone-adhesive low-friction tape is usually better suited despite lower initial tack on polar metals. For cryogenic service below -40 °C, skived PTFE with a silicone adhesive may be preferred because acrylic adhesives can harden and lose peel resilience at very low temperatures.

Evaluating Adhesion Development on Unprimed Metallic and Polymer Surfaces

Adhesion of the acrylic layer is developed through wet-out and dwell rather than through heat activation. On clean stainless steel or aluminum, peel strength per ASTM D3330 is typically in the range of 20 oz/in to 40 oz/in (5.5 N/25 mm to 11.0 N/25 mm) after 20 min dwell, with ultimate strength developing over 72 h at 20 °C to 25 °C. Substrate preparation should include solvent wiping with isopropyl alcohol or heptane followed by a dry cloth. Residual citrus-based cleaners, silicone oils, or paraffinic rust preventives inhibit wet-out and produce edge-lift failures on high-speed conveyor rails.

The adhesive is less effective on low-energy substrates such as unprimed polypropylene, high-density polyethylene, or silicone release surfaces. In those cases, corona or plasma treatment of the counter-surface may improve initial adhesion, but published data for this exact tape on treated polyolefin substrates is limited. For bonding to flexible PVC, plasticizer migration can gradually soften the adhesive interface; a 72 h peel test on the actual substrate is recommended before production use.

On packaging lines, field observations with checkweigher rails and case-erector plough bars indicate that edge lift initiates where the tape is cut sharply across the direction of sliding and where soap-based chain lubricants penetrate the exposed adhesive seam. Rounded corner trimming and sealing of the leading edge with a small overlap reduce fluid ingress. These installation details influence service life more than small differences in nominal film thickness.

When PTFE, Polyester, or Rubber-Adhesive Tapes Are Substituted, Process Conditions Shift in Three Measured Areas

Compared with skived PTFE pressure-sensitive tapes, the CHR 2302-3R construction has a higher dynamic coefficient of friction but greater gouging resistance and impact toughness. PTFE tapes may show dynamic coefficient of friction below 0.10 on polished steel, while CHR 2302-3R generally operates from 0.10 to 0.22. PTFE also offers continuous temperature resistance above 200 °C, whereas the acrylic adhesive on CHR 2302-3R limits continuous use to 82 °C. In abrasive contact with granular product, UHMW often exhibits lower wear than PTFE because the UHMW surface absorbs impact energy without microcracking.

Against polyester film tapes, UHMW provides lower surface friction and better resistance to shatter under repeated impact, but polyester has higher tensile modulus and dimensional stability under tension. A polyester-backed tape may be selected when the tape must maintain a taut wrap or resist puncture from sharp-edged articles. UHMW is more compliant and can follow a slightly uneven guide-rail profile, but it is not suitable for high-tension carrier applications because of its lower modulus and elongation at break.

Against UHMW tapes using rubber adhesives, the acrylic adhesive on CHR 2302-3R provides better ultraviolet resistance and less tendency to yellow or bleed, but initial tack on oily metal may be lower. Rubber adhesives frequently offer higher quick-stick on steel at ambient temperature but soften below 60 °C and may emit higher odor during liner removal. Acrylic transfer adhesives are generally preferred where the tape is exposed to indirect sunlight through polycarbonate guards, because rubber systems degrade more quickly under UV and heat.

Storage conditions influence the acrylate adhesive and the release-liner stripping force. The product should be stored in original packaging at 10 °C to 27 °C and 40 % to 60 % relative humidity. High humidity above 60 % can hydrate the paper release liner, increasing unwind force and creating dimensional growth. Rolls should not be stacked under heavy load because UHMW film can compress and exhibit blocking through the liner under sustained pressure.

In cold-storage conveyor systems operating near -25 °C, peel strength is retained if the tape is applied and allowed to dwell at room temperature for 24 h before the line is brought to temperature. If application occurs directly to cold metal below 10 °C, condensation can form at the adhesive interface and reduce initial wet-out. A hand-held IR heater may raise the substrate to 20 °C to 30 °C before application; direct flame heating is not recommended because UHMW backing can shrink and distort.

Compliance and Test-Method Matrix

Compliance for food contact applies to the polyolefin backing resin; the acrylic adhesive and release liner are not automatically covered by 21 CFR 177.1520 unless separately validated for the intended food-contact configuration. Users should not infer direct food-contact approval for the completed tape without reviewing the specific Saint-Gobain regulatory statement for the adhesive and liner system.

In sliding applications involving dust-laden air or abrasive particulate, the tape is used as a sacrificial wear element on aluminum and stainless steel fixtures, including star wheels on rotary labeling machines and discharge chutes on checkweighers. Installation begins with degreasing using a fast-evaporating solvent. The tape is applied with firm roller pressure over the full width; trapped air can be removed by needling through the film, but needle perforation creates a pathway for water and chemical ingress. Therefore, perforation should be limited to areas outside the direct sliding contact zone.

In wire and cable harness fabrication, the UHMW tape is used as a low-friction overwrap on forming dies and pull-through guides where polyester or PTFE tapes either wear too quickly or transfer adhesive to the jacket. The UHMW film provides a dry-running surface, but sustained high-speed pulling above 1.0 m/s may generate frictional heat sufficient to soften the acrylic adhesive. For such service, a mechanical fastening or an adhesive with higher temperature capability should be evaluated. Published data for high-speed wire-pulling configurations with this exact tape is limited.

In appliance assembly, CHR 2302-3R is applied between stainless-steel chassis panels and polymer brackets to reduce squeak and stick-slip. The tape damps relative movement and prevents galvanic abrasion between dissimilar materials. Since UHMW has low moisture transmission, water trapped beneath the tape on sealed seams can remain present for extended periods; edge sealing with a compatible lacquer is required if the assembly is exposed to frequent condensation.