During turret winder reel changes on a double-coated woodfree line running 115 g/m² sheet at 2,000 m/min, a 12 mm wide single-coated repulpable tissue tape is applied to both faces of a butt joint to maintain web continuity through the winder nip. The local radius increase at the splice equals the tape calliper measured under ASTM D3652/D3652M at 0.08 mm for the standard grade, corresponding to a 24 mm lineal tape coverage per splice line when two strips are used. Under a centre-assisted winder with 1,500 mm diameter parent rolls and nip line load of 3–5 N/mm, this calliper step generates a recurring radial irregularity that shifts the winding hardness distribution in the outer 50 mm of the roll. The failure mode observed on production winders is not splice separation but interlayer shear at the tape edge when drum speed exceeds 1,800 m/min; rolls above 1,200 mm diameter may develop soft bands, recorded on mill winder audit reports as a local Shore C hardness differential of 10–15 points in the splice zone. Because rejected parent rolls, end-sheeting losses, and slitter edge trim return to the mill broke system, the splice assembly must satisfy repulpability screening under TAPPI UM 213, which prescribes laboratory defibering in a hydropulper at 3,000 rpm, 50°C, for 30 min, followed by screening through a 0.15 mm slotted plate with residual stickie rejection limited to trace levels. For food-grade coated grades, the tape is additionally evaluated under FDA 21 CFR 176.170 and BfR Recommendation XXXVI for indirect food contact. The downstream production sequence is: sheet-fed or web offset printing, varnishing, and folding carton conversion; the terminal product consists of palletised ream-wrapped digital or litho sheet stock and printed folding carton flats.

Winder operator control includes a splice position offset of ±25 mm from the sheet edge to prevent tape lifting at the duplex slitter station. The repulpable adhesive chemistry remains dispersed at pulper pH 6.5–8.5, but mill observations on closed-loop white-water systems have documented micro-stickie aggregation above 45°C when alum dosage exceeds 1.5 kg/tonne dry fibre; this is an operational boundary rather than a tape failure. In slitter-winder conversion, the spliced area passes through 10–12 shear slitting positions under an unwinder tension of 250–400 N/m without initiated edge tears; tear initiation data from mill splice audits are limited. The single-coated configuration imposes one further constraint: the non-adhesive tissue side requires a fibre-locked sheet surface, so on supercalendered grades above 70 gloss units with low micro-roughness below 0.8 µm Rz, plant trials indicate that nip-induced slip can initiate at winder speeds above 2,200 m/min; published data for this specific surface-slip configuration is limited.

What Splice Failure Modes Appear After Heatset Oven Aging in Web Offset?

A 965 mm wide heatset web offset press imposes a flying paster splice pattern at a web speed that may exceed 12 m/s, with a 15 mm overlap strip of single-coated repulpable tissue tape, equivalent to 1.6% lineal coverage per splice. Because the splice enters the heatset dryer within 0.4 s of paster contact, the adhesive layer is subjected to a 130–160°C air temperature with a dwell time of 1.0–1.5 s before reaching the chill rolls at 25–30°C. The primary production failure mode is not tensile break of the tissue carrier but adhesive micro-bloom that transfers to the first chill roll surface, manifesting as 0.1–0.3 mm tack dots at the splice perimeter; this accumulates over 20,000 impressions and initiates cylinder wrap marks on the subsequent blanket. Print process compliance is evaluated under ISO 12647-2:2013, clause 4.3.2, for spot colour consistency across the splice boundary, with maximum colour difference ΔE₀₀ held below 2.5 on the splice-bearing signature. Because printed signature broke is sold into de-inking line furnishes, repulpability and deinkability are screened under TAPPI UM 213 and INGEDE Method 12, with the latter measuring dirt specks after flotation deinking and hyperwashing; splice tape residues above 50 µm apparent diameter are classified as visible specks under ISO 15360-1:2000. The press configuration is a dual-web 16-page magazine press, with web tension maintained at 150–250 N/m for 45 g/m² LWC paper. Terminal finished products include magazine signatures, brochure sections, and direct mail flyers.

The heatset oven scenario also involves the post-dryer chill roll labyrinth where web temperatures drop from 160°C to 25°C within 0.8 s, imposing a thermal contraction differential between the tissue carrier and the coated paper substrate. The press auxiliary equipment must maintain festoon tension at 200 N/m during acceleration from zero-speed paster contact to steady state; tension deviations above ±10% at the splice point have been associated with register shifts of 0.2 mm in the subsequent printed form. For publication gravure lines that accept the same parent reels, the spliced web enters an impression roller with surface hardness 85 Shore D; tape calliper is deliberately limited below 0.10 mm to avoid gravure cylinder strike-through. Operational boundary: on press runs using UV-cured inks, the non-adhesive tissue side must not be applied over silicone-treated surfaces because interfacial adhesion loss at oven exit temperatures above 160°C causes edge lift in the folder superstructure.

Corrugator Wet-End Splicing Against 180°C Preheat Rolls

Corrugating medium and linerboard splices on a running corrugator must pass downstream through a preheater section where rolls run at 170–190°C and the web residence time per heating pass is 0.3–0.8 s. For 112 g/m² semichemical fluting medium, a butt splice uses a 12 mm wide strip of repulpable single-coated tissue tape; for 170–220 g/m² kraftliner, the specification typically increases to an 18 mm overlap splice, with the tape occupying 0.7% of the 2,500 mm corrugator web width. Production experience on three-ply corrugators indicates that the peel force at the splice measured under ASTM D3330/D3330M-04 must exceed 2.5 N/25 mm at the preheat roll surface temperature; below this value, web separation at the single-facer nip initiates edge flute crush in B-flute by 12–18% of the side trim width. Compliance for the finished board relies on EN 643:2013 for recovered paper grade classification, FDA 21 CFR 176.170 and EU Regulation (EC) No 1935/2004 for dry food contact of the converted cases. The downstream process involves: unwind strand with zero-speed diaphragm splicer, festoon bridge, glue machine applying corn starch adhesive at 60–70°C, single facer, double backer, and rotary die-cut or flexo folder-gluer. Terminal products include RSC corrugated shipping containers, pizza boxes, and printed shelf-ready cases. Operational boundary: the tape must not be positioned so that it passes directly under a steam shower before the single facer; during mill audits, condensate wetting of the non-adhesive tissue face at 95–100% relative humidity for more than 4 s has been associated with a measurable reduction in shear adhesion under ASTM D3654/D3654M-06.

On 2,500 mm corrugators equipped with hydraulic diaphragm splicers, the splice assembly is accelerated from zero to line speed within 1.2 s during the changeover, subjecting the tape to peel forces that are 1.5–2.0 times higher than the static peel value obtained under ASTM D3330/D3330M-04 at 23°C. The tissue carrier of the single-coated structure provides a low elongation of 5–8% under TAPPI T 494 om-06, which transfers the acceleration impulse across the butt joint without inducing a tension spike above 450 N/m. Mill logs on a three-ply corrugator running B-flute with 112 g/m² medium at 350 m/min have recorded no splice-related single-facer blockage when the tape width is limited to 12 mm and the preheater surface temperature does not exceed 190°C; above this temperature, the adhesive layer begins to soften and the splice may drift under single-facer nip draw.

At tissue converting speeds above 600 m/min on a double-drum rewinder processing 17 g/m² dry-creped base paper, butt splices made with single-coated repulpable tissue tape are used to join jumbo reels before the embosser and log saw. A single 12 mm wide strip is applied over the butt joint on the full 2,700 mm web width, providing lineal tape coverage of 0.44% per splice line. Because the finished household roll may contain one splice per 80,000–120,000 m of converted tissue and because converting broke is re-fed into the stock preparation line, the splice tape must disperse in the same pulper used for recovered tissue under EN 643:2013. Compliance for the finished product under the EU Ecolabel for tissue products, Commission Decision (EU) 2019/70, requires that recovered fibre content and chemical oxygen demand in process water remain within defined limits; repulpable splice components that leave visible stickies above 50 µm would be recorded as contaminants. The converting line is configured with unwind, festoon accumulator of 3–5 m storage, combined laminating and embossing unit at 80–100 kN/m nip line force, rewinder, log saw, and packaging. Terminal products include 2-ply and 3-ply kitchen towels, bathroom tissue rolls, and industrial wiper rolls.

During a converting batch change, the splice enters the rewinder under a rewind tension of 300–450 N/m; the tape carrier elongation at break under TAPPI T 494 om-06 is reported in the 5–8% range, below surrounding tissue elongation of 10–14%, which concentrates tension locally and shifts perforation length targets by 0.25–0.5% in 110 mm finished roll widths. Mill audits of splice-bearing logs have not documented statistically significant log saw dust increases beyond baseline tissue dust for the same furnish; published gravimetric dust data for this specific configuration is limited. The single-coated design imposes one process constraint: on tissue grades above 16% crepe ratio, tape-to-sheet conformability at the embosser nip may be insufficient where embossing roll temperature exceeds 90°C; published data for this specific embossing configuration is limited.

When Silicone-Coated Release Liner Splices Re-Enter the Pulp Furnish

Release liner converting operations on PSA labelstock lines splice silicone-coated glassine or clay-coated kraft liners with repulpable single-coated tissue tape in butt orientation at die-cutting presses. A 9 mm wide tape strip is used on a 1,000 mm web width, equivalent to 0.9% lineal coverage, with the splice interval defined by the reel change cycle of the die press. The operational reason for requiring repulpability is that used release liner waste is baled and sold as recovered paper grade under EN 643:2013, and non-repulpable splice tape would create stickie contamination in tissue or printing paper furnish when the liner is re-pulped. Compliance screening follows TAPPI UM 213 for repulping and ISO 15360-1:2000 for microscopic stickie counting, with acceptance criteria aligned to a residual visible stickie count not exceeding the pulper supply specification. In the die-cutting process, the splice passes under a flatbed die station with kiss-cut pressure of 8–12 N/mm²; splice failure at this stage appears as edge lift at 90° peel angles during matrix stripping. The downstream sequence is: adhesive coating, lamination to face stock, die cutting, matrix stripping, and re-winding; terminal products include pressure-sensitive label release liners, graphic film liners, and tape backings. For food-label applications, finished laminate compliance references EU Regulation (EC) No 1935/2004 and FDA 21 CFR 175.105 for adhesive components. Operational boundary: when clay-coated kraft liner grammage exceeds 120 g/m² and silicone curing oven dwell exceeds 15 s at 150°C, the tape adhesive begins to soften at the liner interface; published shear data for silicone-repulpable splice combinations under these specific cure conditions is limited.

The die-cutting operation also imposes cyclic flexure on the splice as the web passes around a 40 mm radius anvil roll at 180 m/min. Because the tissue carrier retains folding endurance without cracking, matrix stripping breakage does not initiate at the splice line; cyclic fatigue data specific to silicone-coated liner splices under repeated flexure is limited. Converter control procedures therefore restrict splice tape width to 9 mm on liners below 60 g/m² to reduce the flexural stress concentration at the tape edge.

Because kraft sack bottomers apply aqueous starch and latex adhesives at 60–70°C on a cross-ply bottom patch, a butt splice in 70 g/m² extensible sack kraft must survive the bottomer adhesive station without delamination. A 10 mm wide strip of single-coated repulpable tape is applied over the butt joint on an 850 mm web width, giving 1.2% lineal coverage per splice. The tuber-bottomer line configuration comprises unwind, corner-cutting station, tubing section, multi-stage bottom patching, and valve insertion; the splice passes through the bottomer at 250–350 sacks/min on modern flat-bed equipment. Terminal products include 25 kg cement sacks, pet-food multiwall sacks, and dry food ingredient bags. For direct food-contact fills below 1 kg, compliance is assessed under EU Regulation (EC) No 1935/2004 and FDA 21 CFR 176.170; recovered pre-consumer sack waste reverts to the appropriate EN 643:2013 recovered paper grade for repulping. The splice tape does not alter the sack bottom tensile strength measured under ISO 1924-2:2008 at standard atmosphere, provided the splice is positioned outside the folded bottom patch zone. Repulping of pre-consumer sack waste requires the same TAPPI UM 213 screening, and the tape residue in the pulper remains below the visible stickie threshold when the hydropulper temperature stays below 60°C.