In continuous web converting lines where polyester and polyimide webs are butt-joined before corona treatment or gravure coating, 3M 9498 Splicing Tape is installed as a single-coated polyester film tape with a silicone pressure-sensitive adhesive. The construction uses a 0.025 mm polyester carrier and a silicone adhesive layer; total manufacturer-reported thickness is 0.064 mm (2.5 mil), and standard roll configurations include widths from 12 mm to 100 mm on 76 mm cores. Published physical properties under ASTM D3652 and ASTM D3759 include tensile strength at break of 438 N/100 mm (25 lb/in) and elongation at break of approximately 100%. Peel adhesion to stainless steel is typically 38 N/100 mm (35 oz/in) when tested at 180° pull angle and 300 mm/min crosshead speed per ASTM D3330. The silicone PSA differentiates 9498 from acrylic splicing tapes in two measurable ways: lower glass transition temperature, approximately −55 °C, and higher continuous-temperature capability, with manufacturer data generally supporting splice dwell up to 204 °C (400 °F), not indefinite exposure. These properties position the tape for high-temperature web splicing in coating, laminating, and label-converting operations, not for general packaging or carton sealing.

In release-liner and label-converting applications, the product is used as a butt-splice tape on release-coated paper liners, polyester carrier films, and polyimide electrical webs. It is not designed as a bonding tape for low-surface-energy plastics unless corona treatment or plasma activation is applied. The polyester backing resists hydrolysis better than cellulose-based splicing tapes, but it does not provide flame retardancy or UL 510 recognition in every configuration. Compared with rubber-resin splicing tapes, 9498 leaves no sulfur-containing residue at high temperature and does not corrode copper or silver-containing films. Compared with acrylic adhesive tapes, it exhibits lower initial tack on unprimed polypropylene but higher shear at elevated temperature and better wet-out on polydimethylsiloxane release surfaces. Compared with polyimide splice tapes, it offers lower caliper and lower cost per linear metre, but a lower maximum continuous temperature. These differences do not appear under ambient conditions and become relevant only after the splice passes through an oven, dryer, or solvent station. Rolls are supplied with a silicone release liner to protect the exposed adhesive during slitting and handling; liner removal force should be checked when changing suppliers because silicone-to-silicone interactions can vary with liner cure level.

What Limits a Silicone-Adhesive Splice in Multi-Zone Flotation Dryers?

Within a multi-zone flotation dryer, the web is supported by air bars, and splices must survive repeated thermal cycles instead of a single oven pass. Failure typically initiates at the trailing edge when the adhesive has not been burnished into the substrate; the peel front propagates at air-bar impingement velocities above 25 m/s. The relevant test is not room-temperature peel but elevated-temperature shear. Manufacturer literature for 9498 reports static shear resistance of 1 kg at 150 °C with no failure in 24 h, whereas a general-purpose acrylic splicing tape fails in 2–4 h under the same conditions. On a production coater running 0.025 mm polyester film at 90 m/min, the splice dwell inside a three-zone dryer at 160 °C is 12–15 s; this is within the adhesive’s continuous-temperature envelope, but the leading edge may see 180 °C on the film side. Operators place the splice tape on the side that contacts the initial chill roll, not the side facing the first active dryer zone.

Another limitation is adhesive softening at the edge of the polyester carrier. At temperatures above 175 °C, the adhesive can flow laterally under 10 N/100 mm web tension and leave a residue on idler rolls. This condition is most severe when splicing unsupported films below 0.012 mm thickness, because the film provides little thermal mass to dissipate heat. Use of 9498 in these conditions requires a roving-edge splice with the tape cut 2–3 mm narrower than the web, plus an idler roll surface of low-release plasma-coated steel. Published data for the specific residue load after 50 h elevated storage in a spliced configuration are limited; qualification trials are recommended.

On zero-speed splicers with roll-side accumulator dwell of 30–45 s, the splice remains stationary while the accumulator pays out web. This dwell at 180 °C can produce creep of an improperly crosslinked acrylic adhesive; for 9498 the failure mode shifts to peel at the splice edge if the tape length is less than the full web width plus 5 mm. An 18 mm wide splice on a 1.6 m web with a 10 mm edge gap allows edge flutter to lift the unsupported film and initiate tearing at the lead edge. In production trials, full-width butt splices with tape overhang of 2 mm on each side reduce edge-lift-related breaks but increase idler contamination from exposed adhesive at high temperature. The preferred configuration for 0.025 mm polyester is a tape width 2 mm narrower than the web, with edge tacking by a 6 mm strip of the same tape applied at 45° to the edge. Unlike moisture-set or UV-cure splicing tapes, 9498 requires no cure after application, so it is suitable for zero-speed splicing where the splice enters the process within seconds after placement.

On label converting unwind stands with festoon accumulation, the caliper step created by the splice is more critical than peel strength. A butt splice made with 0.064 mm tape introduces a thickness step equal to the total tape thickness; at a rotary die station running 12–15 m/min, this step deflects the die and causes incomplete matrix stripping on 0.050 mm polyester film. The 0.025 mm backing keeps the step low, but the splice must be applied with the adhesive layer toward the film face and burnished with a low-friction roller to prevent lint entrapment at 15–20° wrap angles. The product is often compared to thicker polyester tapes such as 8902: 9498 is selected where caliper uniformity is the controlling variable, while 8902 is specified where edge reinforcement and impact resistance on thicker film outweigh caliper concerns. On release-coated backings with a silicone liner, the silicone PSA wets the liner better than an acrylic PSA, but this same property makes splice removal difficult if the liner is reused in automatic label dispensing. In roll label presses with hot air dryers operating above 160 °C, the splice tape on the release liner can shrink if the adhesive is not uniformly applied; differential thermal expansion between the polyester carrier and the paper liner creates curl that lifts the splice edge before the die cut. Pre-curling the tape or applying it along the web centreline can reduce this effect.

Carrier Dimensional Stability and Electrostatic Discharge Control During Unwind

Polyester film in 9498 has a coefficient of thermal expansion of approximately 20 × 10⁻⁶ m/(m·K) and moisture absorption below 0.8% at 23 °C, so splice tapes do not develop hygroscopic curl after exposure to solvent-laden air. On an unwind running at 250 m/min, the splice edge can accumulate charge because the tape is an insulator; the dielectric breakdown strength is typically 5.5 kV for a 0.064 mm total thickness, but this value is a dielectric strength measurement, not an antistatic function. Accumulated charge on metallized polyester webs with surface resistivity below 10¹¹ Ω/sq can create discharges sufficient to ignite solvent vapours in gravure coating. Therefore 9498 requires external static control—ionizing bars, grounded carbon-brush supports, or conductive core shafts—when used in Class I, Division 2 solvent-handling areas. The tape itself does not contain conductive fillers, and no static dissipative grade is available in the 9498 family.

Tension control is also affected by the carrier’s modulus. Polyester film exhibits tensile modulus around 3.8 GPa; converting calculations show that a 1.6 m wide web at 600 N line tension produces an elongation below 1%, which is acceptable for zero-speed splicers. However, when the splice is located between the load cell and the lay-on roller, the tape’s strain recovery after tension release can cause a 0.5–1.5% length error in registration; this is corrected by placing the splice downstream of the dancer assembly. On a solventless laminator using polyurethane adhesive at 45 °C, static discharge from the splice can create gel particles in the adhesive; use of the tape as a splice over a conductive carbon-black antistatic layer is preferable to splicing the bare insulating film.

When High-Temperature Splices Are Exposed to Fluorosilicone Release Liners, Adhesion Transfer Can Occur

Fluorosilicone release liners and silicone-coated papers present low surface energy surfaces. The silicone PSA on 9498 wets polydimethylsiloxane surfaces more effectively than acrylic PSA, but the same compatibility can cause blocking if the spliced roll is stored above 40 °C for more than 72 h. In those conditions, adhesive can transfer to the liner and create residue that interferes with ink anchorage at the next converting step. To prevent this, the tape is placed with the adhesive against the film face rather than the release side, or a polyester interleaf is used on the liner side. When the splice must contact a silicone liner, converters can apply a primer or use a tape with a fluorosilicone adhesive instead, though published data for this specific configuration are limited. Peel force for release liners is commonly measured at 0.30 m/min peel rate and 180° angle; values below 0.05 N/100 mm indicate release failure, while values above 0.10 N/100 mm indicate liner blocking.

Chemical compatibility defines another operational boundary. The silicone adhesive resists many acids, alkalis, and aliphatic hydrocarbons, but prolonged immersion in ketones, chlorinated solvents, and aromatic hydrocarbons swells the adhesive and reduces shear strength. In printing lines using ethyl acetate or methyl ethyl ketone, the splice tape should not be wetted by solvent splash; if solvent contact is unavoidable, a polyimide tape with a silicone adhesive may be substituted because the polyimide carrier withstands higher solvent uptake. However, polyimide tape has lower tear resistance on a slitter. Unopened rolls of 9498 are stored at 20–25 °C and 40–50% relative humidity, with a shelf life of 24 months from shipment when kept in original packaging. Rolls exposed to sub-zero temperatures should be conditioned at 23 °C for 24 h before unwind to prevent polyester embrittlement.

Slitting operations on spliced rolls require edge alignment to prevent telescoping. A splice made with 9498 on a 1.6 m wide web and slit into 24 mm lanes exhibits lateral shear at the splice boundaries if the tape is not cut through simultaneously with the web. When the parent roll is run at 600 N tension and 400 m/min, the polyester carrier restricts elongation to under 1%, but localized adhesive creep can permit lane-to-lane drift of 0.1–0.2 mm. Operators therefore index splices between slitter blades and inspect the first 10 m after every splice, especially when converting metallized polyester where edge lift causes static discharge. On duplex slitters with differential rewind shafts, the tape must not overlap the core gap; otherwise oscillation at the rewind station induces peel initiation at the splice edge. Slitters with shear-cut knife geometry also require the tape to be resistant to adhesive build-up on the upper knife; periodic wiping with isopropyl alcohol is specified because silicone adhesive transfers to the knife edge and can cause a ragged slit on subsequent lanes.