Saint-Gobain CHR 2829-5(R) Acrylic Adhesive Zone Tape is a pressure-sensitive splicing medium in which a polyester film carrier is coated on two separated edge bands with an acrylate pressure-sensitive adhesive, leaving the central web free of adhesive. The -5 suffix denotes a nominal carrier thickness of 5.0 mil (0.127 mm); the (R) marker appears in distribution part numbers and certificates as a configuration identifier within the CHR 2829 series. Standard distributor stock widths include 12.7 mm, 25.4 mm, 50.8 mm, 76.2 mm, and 101.6 mm (0.5 in, 1.0 in, 2.0 in, 3.0 in, 4.0 in), with the adhesive edge band commonly specified at 12.7 mm (0.5 in) on each longitudinal edge. The product is used where mechanical continuity of a splice is required, but adhesive is not permitted across the full web width because of contamination, resin-flow blockage, or adhesion to a tool surface. Unlike a full-width transfer tape, the zoned geometry confines the acrylic to the border regions, leaving the central region clean and essentially non-reactive during layup and cure.

What Process Boundary Conditions Govern Use in Vacuum Bagging?

In vacuum bagging, CHR 2829-5(R) is applied across butt splices of release film, woven breather, or peel ply, with each acrylic edge band bonded to the top surface of the web. The splice must be positioned so that the adhesive-free center coincides with the butt gap and does not contact the part or the resin flow channel. Wet-out is performed at 20 °C to 25 °C and at a consolidation vacuum of approximately -85 kPa gauge (12.5 psia) before ramping to cure. On autoclave-cured epoxy prepreg systems with cure temperatures from 121 °C to 177 °C, the edge adhesive should be tested after 24 h at the maximum cure condition by peel adhesion according to ASTM D3330/D3330M. Published data for this specific configuration above 177 °C is limited; silicone-based splicing tapes or polyimide-backed tapes are substituted when cure exceeds 200 °C. The central adhesive-free zone prevents tack transfer to breather fabric and avoids local stiffening of the release film during dwell. Splice failure on production gantry cutters is usually induced by shear creep under constant web tension rather than by low peel; validation is performed with a dead-load shear test according to ASTM D3654/D3654M at 70 °C using a 1.0 kg mass on a 25 mm × 25 mm bonded area. The specimen is cut with a single-edge razor at 25 mm width to avoid edge nicks that concentrate stress. Autoclave pressure of 0.586 MPa to 0.689 MPa (85 psi to 100 psi) applied after initial vacuum debulk does not typically degrade the splice when the adhesive-free central region remains dry; any edge wicking of resin along the polyester carrier must be rejected.

In automated cutting-table and ply kitting operations, the tape is applied across roll splices of release paper and woven breather because the central adhesive-free area prevents the splice from becoming a resin-flow choke point during infusion. The polyester carrier passes over nip rollers and dancer bars at web tensions from 10 N to 30 N per linear meter without acrylic transfer to the rollers. Residue from the edge bands is checked by post-peel inspection of stainless steel panels under ASTM D3330/D3330M; peel adhesion values of 5 N/25 mm to 20 N/25 mm at 180° are generally sufficient for polyester release films, while porous breathers may require a wet-out dwell of 15 s to 30 s before vacuum is applied. Batch-to-batch variation on low-surface-energy release films can produce a peel shift of ±2 N/25 mm between lots; incoming inspection should compare the release liner side and the matte side rather than relying on a single universal value. A common production defect is adhesive transfer at the cut edge caused by slitter burr; incoming rolls should be inspected at 10× magnification and any visible adhesive debris rejected before splicing.

Adhesion Test Methods and Release Liner Characterization

Acceptance for a given vacuum bagging sequence is based on peel adhesion, loop tack, shear adhesion, backing tensile, and optional outgassing. Conditioning is performed under ISO 554 atmosphere 23 °C ± 1 °C and 50% ± 5% relative humidity for 24 h before testing. Stainless steel panels used for peel are prepared according to ASTM D3330/D3330M; for low-energy substrates, dyne solutions conforming to ASTM D2578 or ISO 8296 document surface energy before lamination. Typical test output is compared to the process specification, not to a generic databook value.

Lot-specific values for CHR 2829-5(R) should be read from the manufacturer certificate of analysis. Published data for the exact zoned configuration is limited for outgassing; therefore ASTM E595 testing is performed only when the application requires low condensable volatile control. Raw acrylic pressure-sensitive adhesive is not inherently low-outgassing, and any silicone-free status must be confirmed by lot-specific Fourier-transform infrared spectroscopy or gas chromatography review when secondary bonding is required.

When compared with a full-width acrylic transfer tape, Saint-Gobain CHR 2829-5(R) reduces the adhesive width from 100% of the web to two edge zones, commonly 25% to 50% of the total width depending on roll width and zone geometry. This geometric change reduces contamination and avoids adhesive contact with resin channels, but it also lowers total splice holding force; process engineers must not apply the same N/25 mm peel value used for a full-width tape without multiplying by the actual bonded width. Against a silicone-adhesive glass cloth splicing tape, the acrylic zones provide higher initial grab on polyester and nylon bagging films and avoid silicone oligomer transfer after cure, but the acrylic has a lower service ceiling. Against a skived PTFE-coated tape, the polyester carrier of CHR 2829-5(R) has higher tensile stiffness and lower elongation, and the exposed polyester surfaces are less slippery than PTFE-coated surfaces. The matrix below summarizes typical comparison points.

The substitution of CHR 2829-5(R) for a silicone-coated tape is appropriate when secondary bonding or painting is performed after stripping. Silicone contamination is detected by water-break-free surface checks or contact-angle measurements per ASTM D5946. On polyimide bagging films and plasma-treated release films, the acrylic zones maintain peel strength better than medium-tack silicone systems, but the polyester carrier can produce a sharper fold at the splice than a conformable glass cloth tape.

When Acrylic Adhesive Zone Tape Replaces Silicone-Coated Splicing Tape in Closed Molding

In closed molding processes such as RTM and vacuum-assisted RTM, the tape is placed only in peripheral flange areas outside resin-wetted channels. The adhesive-free center must follow the tool parting line; edge bands are bonded outside the gasket or seal location. The acrylic edge bands should not be wetted with styrene-containing vinyl ester resin because monomer absorption can plasticize the pressure-sensitive adhesive and reduce shear adhesion. Published data for this specific configuration under resin immersion is limited; the standard screening method is to expose the splice to the target resin system at 25 °C for 72 h and then measure peel adhesion according to ASTM D3330/D3330M. For epoxy prepreg systems cured at 121 °C, the adhesive demonstrates adequate tack when the tool surface is prepared to at least 38 dyn/cm measured by ASTM D2578 or ISO 8296. On a production resin injection line running a metering pressure of 0.5 MPa (72.5 psi) and a mold shell temperature of 60 °C, edge tape creep larger than 0.5 mm after 2 h is considered a failure boundary; a vacuum leak check at -80 kPa for 15 min prior to injection is the standard process control. Avoid ketone, ester, and aromatic solvent wipe-downs before splicing because these solvents penetrate and soften the acrylic. Isopropanol/water at 70:30 v/v is preferred; evaporation must be complete before the tape is applied. Do not apply below 10 °C because acrylic tack is too low. Do not use over fluoropolymer release surfaces with a wetting tension below 30 dyn/cm unless corona or plasma treatment is applied and verified with dyne pens.

Storage of CHR 2829-5(R) in the original sealed bag at 20 °C ± 5 °C and 50% ± 10% RH maintains roll geometry. A maximum stack height of 5 cartons is imposed to prevent edge blocking or liner telescoping. Shelf life for acrylic pressure-sensitive splicing tapes is commonly assigned as 18 months from date of manufacture when stored under these conditions; after expiry, peel adhesion and loop tack should be checked under the methods listed in Table 1 before production release. Regulatory status is governed by EU REACH Regulation EC No 1907/2006, particularly Annex XVII restrictions, and the RoHS Directive 2011/65/EU as amended. Users should request lot-specific SDS and declarations because regional roll stock may differ in liner type and coating weight.