Saint-Gobain CHR M734 polyester film/natural rubber adhesive tape is applied at reel changeover in high-speed roll-to-roll printing, coating, and laminating lines as a zero-speed or flying splice medium. The polyester backing of nominal thickness 23–25 µm is selected because its secant modulus resists the tensile spike generated when a stationary web is accelerated to match a running web. For polyester film of this thickness, tensile strength typically falls in the range of 100–150 N/25 mm and elongation at break remains below 120% when tested per ASTM D882-18. Splice failure in production occurs less often from backing fracture and more often from adhesive shear displacement between the tape-adhesive interface and the incoming substrate, particularly when the substrate carries a corona-treated surface exceeding 40 dyn/cm or contains migrating slip agents. To reduce this, the tape is applied with a defined unsupported adhesive exposure of 10–20 mm and pressed by a rubber-covered nip roll at a durometer of 70–80 Shore A. The adhesive composition is a natural rubber-resin blend in which the tackifying resin content is typically maintained between 80 phr and 120 phr relative to elastomer; coat weight of 25 g/m² to 35 g/m² is common for splicing grades. Below 18 g/m² the splice peel force on clay-coated paper may fall below the required 1.0–1.5 N/mm after a 20-minute dwell, while above 40 g/m² adhesive ooze from the splice can transfer to idler rollers. Terminal products include printed PET/PE laminates, metallized snack packaging, and release-liner-supported label stock. Compliance for the converting sector is governed by REACH Annex XVII restrictions on polycyclic aromatic hydrocarbons and by the RoHS Directive 2011/65/EU where the finished packaging enters electronics logistics. Adhesion is measured according to ASTM D3330/D3330M-22, tensile strength and elongation per ASTM D882-18, thickness per ASTM D3652/D3652M-20, and static shear holding power per PSTC-107. Operational limits: the natural rubber adhesive softens above 70°C; splicing applications that pass through a post-splice drying tunnel above 80°C show adhesive shear thinning and potential splice slip. Aromatic and ketone solvents present in flexographic inks can migrate into the adhesive edge and reduce spliced web retention; solventless UV inks are compatible provided the tape is spliced before the UV cure station.

What restricts a natural-rubber-film adhesive tape to non-oil-immersed coil and cable insulation?

Polyester film itself has dielectric strength in the range of 7–9 kV/25 µm when measured per ASTM D149-20 using 25 mm electrodes and a 500 V/s ramp, but the tape system’s insulation value is dominated by the adhesive layer and by air entrapment during coil wrapping. In motor coil outer-wrap and harness-facing insulation, the tape is tensioned at 20–50 N/25 mm width during automatic taping heads, and the polyester backing resists thinning under this load. The natural rubber adhesive layer conforms to rectangular copper and aluminium conductors but retains a measurable compression set under hot-test conditions. For coil processing, the tape is typically applied with a 50% overlap using a taping speed of 1–3 m/s, then the winding is varnished or trickle-impregnated. The natural rubber adhesive may swell in polyester or epoxy varnish solvents; pre-qualification with ASTM D471-16 immersion in the specific varnish solvent is required before production. Electrical-grade acceptance uses ASTM D1000-17 for pressure-sensitive tape construction, ASTM D149-20 for breakdown voltage, ASTM D257-19 for insulation resistance, and if the assembly is subject to UL listing, UL 510 and UL 746A RTI values must be obtained from the supplier’s UL yellow card. The adhesive formulation for electrical use generally limits fillers to non-ionic grades; conductive carbon black and metallic oxides are excluded. Processing ratios for natural rubber electrical tape include a sulfur-free cure system or minimal sulfur at 0.5 phr to 1.0 phr to avoid corrosion of copper conductors under humid ageing at 85°C/85% RH. A compliance checklist matrix is provided below.

Published data for this specific configuration in inverter-fed motor partial discharge environments is limited; qualification must be performed against the actual insulation system. Natural rubber adhesive should not be used in oil-filled transformer assemblies because aliphatic hydrocarbon oil can extract adhesive plasticizer and cause detachment. The terminal products that use this tape include low-voltage appliance motors, solenoid coils, and shielded sensor leads where oil immersion and continuous Class H thermal exposure are absent.

When low-bake coating lines select a polyester/rubber masking tape for edges and fixture contact points

Low-bake two-component polyurethane and air-dry alkyd coating lines operate at curing temperatures of 60°C to 80°C for 30–60 minutes. Under these conditions, a polyester film backing with natural rubber adhesive masks edges, holes, and fixture contact points on aluminium extrusions and sheet metal prior to spray application. The polyester film retains at least 80% of its original tensile strength after immersion in a pH 8.0 waterborne clearcoat bath at 60°C for 60 minutes, measured per ASTM D882-18. The natural rubber adhesive provides quick tack to degreased metal without the need for corona treatment. The masking tape is typically applied with a 50% edge compression using a hand roller; for automatic masking stations, unwind tension is kept below 5 N/25 mm width to avoid elastic recovery and lifting. The adhesive layer is formulated with a high-molecular-weight natural rubber fraction and a rosin-ester tackifier ratio of 1:0.8 to 1:1.2; lower tackifier content reduces initial tack on phosphate-treated steel, while higher content increases adhesive transfer after the bake. Peel adhesion after the bake must be tested per ASTM D3330/D3330M-22 at 23°C and at 80°C. One processing conflict occurs when the spray paint solvent is a glycol ether or ketone; the solvent can diffuse through the adhesive edge and plasticise the rubber, producing a gummy residue at demasking. To reduce this, tape edges are detackified by applying a clear lacquer strip or the tape is removed within 15 minutes of oven exit. For powder coating lines above 180°C, this tape is not recommended: published data for this specific configuration is limited, and natural rubber degrades rapidly. Compliance is managed through REACH documentation and the RoHS Directive 2011/65/EU for metal construction products entering the EU. Terminal finished goods include masked architectural aluminium frames, heat-exchanger end plates, and control panel covers.

Corrugated and paper sack converting lines use the tape for roll-start adhesion and for reinforcing splices on kraft liner, coated white-top, and lightweight recycled medium. The polyester film backing prevents tape elongation when the web passes over a steam-heated preheater drum at 100–120°C; elongation under a 10 N/25 mm load remains below 2% in the machine direction per ASTM D882-18. The natural rubber adhesive remains tacky at the initial contact temperature but loses shear strength if the splice dwells under hot-rope tension for more than 60 seconds, as determined by loop tack per ASTM D6195-22 and shear adhesion at 80°C under 500 g load per PSTC-107. A typical splice uses a double-sided construction with the tape product applied over a butt joint and then compressed by the corrugator’s static splice bar at 0.2–0.4 MPa. The adhesive coat weight for paperboard splicing is often specified at 30–40 g/m² to fill the surface roughness of recycled liner; lighter weights below 20 g/m² produce inadequate fibre tear on high-static-charge paper. Adhesive composition includes a process oil or plasticizer at 10–20 phr to maintain low-temperature tack at 5°C in unheated winter plants, but this plasticizer can migrate into uncoated paper and cause staining if the splice is reheated after storage. Terminal products include corrugated shipping containers, multi-wall paper sacks, and preprint liner. The applicable standard for paper tensile breaking properties is TAPPI T 494 om-22, and splice peel on liner is evaluated using ASTM D3330/D3330M-22 with the paper as substrate; tape construction is measured by ASTM D3652/D3652M-20 and peel adhesion by PSTC-101. Compliance checks include FDA 21 CFR 176.170 and 176.180 only when the splice is retained in food-contact packaging; otherwise REACH and RoHS are the governing frameworks. Natural rubber adhesives are not suitable for spliced paper that will be exposed to UV-curing units or high-intensity IR dryers because adiabatic heating at the splice line can exceed the adhesive’s 80°C continuous-use threshold.

Filament winding, mandrel gripping, and the role of polyester-film interleave under resin wet-out

Where carbon fibre or glass fibre tows are spiralled onto a rotating mandrel for pressure vessels, drive shafts, or composite poles, a polyester-backed natural rubber adhesive tape is used to hold the peel ply, thermocouple leads, and vacuum bagging components in place before cure. The tape is applied to the mandrel or to the first layer at a controlled tension of 10–20 N/25 mm width; polyester backing avoids the fibre print-through that occurs with thicker cloth tapes and maintains dimensional stability during roller pressure. Thickness variation across the tape is controlled within ±5 µm per ASTM D3652/D3652M-20. Natural rubber adhesive provides initial tack to low-energy release fabrics and bagging films, but the tack drops sharply if the adhesive is contaminated with epoxy resin component B or anhydride hardener. In production, hand laminators frequently pre-cut the tape into 50 mm lengths to prevent continuous spool contamination; full-width wrapping under resin reflux causes adhesive softening and transfers residue to the laminate surface. The adhesive is formulated with a low molecular weight liquid rubber fraction of 10–30 phr to maintain conformability at 15°C shop floor temperatures, while the high molecular weight fraction provides shear holding during mandrel rotation at 5–15 rpm. Compliance is controlled by REACH and by aerospace qualification standards where applicable; flammability of the tape must be evaluated against FAR 25.853 if the composite part enters an aircraft interior. The peel adhesion is tested per ASTM D3330/D3330M-22, backing tensile per ASTM D882-18, and thickness per ASTM D3652/D3652M-20. A production failure observed on four-axis filament winders is the telescoping of adjacent tape layers when mandrel speed changes by more than 30% in under one second; this occurs because the natural rubber adhesive responds to shear with creep, so a tape with higher static shear is preferred for variable-speed winding. Terminal products include compressed natural gas tank overwraps, composite utility poles, and filament-wound drive shafts.

Solvent-borne ink cleaners will define the maximum service envelope for frame-sealing tape

Screen printing frames are sealed inside the mesh-to-aluminium perimeter with a polyester film/natural rubber adhesive tape to prevent ink leakage under the emulsion edge. The tape is applied after degreasing and before or after emulsion exposure, with an overlap of 10–15 mm. Polyester backing resists aliphatic and aromatic solvents in solvent-based plastisol inks; dimensional change after 60-minute immersion in toluene at 23°C remains below 1% when evaluated per ASTM D543-20. The natural rubber adhesive is selected because it can be removed from aluminium frames with mild solvent without attacking frame anodising. The adhesive thickness is controlled to 25–35 g/m² to fill mesh knuckles of 90–160 threads/cm. Failure occurs when the tape is subjected to ink cleaners containing ketones such as cyclohexanone or MEK; the rubber adhesive swells and releases within 5–10 minutes. Production therefore removes the tape before aggressive cleanup cycles. The tape is not exposed to the curing tunnel, so the 80°C continuous-use limit is not exceeded. Compliance is governed by REACH Annex XVII entries 51 and 52 for phthalate restrictions in printed garments and by RoHS Directive 2011/65/EU for electrical components. Standards used for incoming inspection are PSTC-101 for peel adhesion, ASTM D3652/D3652M-20 for thickness, and ASTM D882-18 for tensile strength. Terminal goods include screen-printed apparel, graphic posters, and textile banners.