On publication-grade winders handling uncoated groundwood and supercalendered papers, web speeds commonly reach 1,600–2,200 m/min across widths of 8.4–10.4 m. The tension envelope during a flying splice is typically 0.7–1.5 kN/m on basis weights between 40 and 52 g/m². In this application, the R3127 single-coated repulpable tape is used as a butt splice with an overlap length of 50–75 mm. The single adhesive layer is placed between the outgoing sheet and the incoming sheet, leaving no secondary carrier ridge that could excite hard-nip calender vibration or cause sheet marking at 40–60 °C residual reel heat. Static shear adhesion on stainless steel is measured according to ASTM D3654/D3654M-06, usually at 23 °C and 50 % RH with a 1 kg load, but the controlling mill variable is dynamic creep under web tension. When a splice-bearing broke reel is returned to the pulper, dispersion is evaluated in an ISO 5263 laboratory disintegrator at 3 % consistency and 45 °C for 30,000 revolutions; subsequent screening through a 0.15 mm slotted laboratory screen is used to confirm that no visible adhesive agglomerates remain. Mill-scale broke pulpers operate at 5–8 % consistency, 45–70 °C, and 15–30 minutes retention, where the limiting criterion is not fiber yield but the absence of dispersed adhesive specks that could pass to the headbox and form defects in the final sheet.

What Drives Splice Release in Low-Basis-Weight Tissue Converting?

Tissue parent rolls differ from publication grades in basis weight, caliper, wet-end chemistry, and converting draw control. Parent rolls for tissue and towel grades are typically wound at 600–900 m/min with basis weights of 15–30 g/m² and widths of 2.0–2.7 m. The splice must survive re-winding, log sawing, and downstream converting where draw ratios between roll stands may shift from 0.1 % to 0.5 %. A splice that survives the winder may still fail at converting because the low stiffness of the tissue web transfers higher strain to the tape edge. For this reason, butt splices are made with the adhesive side oriented to minimize caliper step, and the tape is applied under controlled pressure to prevent edge lift during log saw oscillation. Repulping conditions for tissue mill broke are commonly 4–6 % consistency at 50 °C and pH 7–8. The presence of polyamide-epichlorohydrin wet-strength resin in the furnish can slow initial water uptake, but the adhesive component is water-dispersible under these conditions. The repulpability acceptance criterion in tissue mills is frequently tied to a slotted screen of 0.20 mm or finer, because any remaining adhesive particle can produce pinholing in 15 g/m² grades. Edge flagging on low-basis-weight webs is also a practical failure mode when the tape is applied with insufficient wetting on dusty creped surfaces; production lines address this with anti-static bars and vacuum-assisted web control at the unwind.

Corrugated Medium Roll Stands and Cross-Direction Shear Concentration

In corrugated medium converting, roll stand splices are made on basis weights of 112–200 g/m² at single-face corrugator speeds of 300–450 m/min. Roll stand tension is typically 0.8–1.5 kN/m, and the splice is subjected to acceleration from standstill to line speed within 5–15 seconds. On rotary splicers with festoon accumulators, the new roll is pre-accelerated to 60–80 % of line speed before the splice is initiated, but the remaining speed differential creates a tensile shock that concentrates cross-direction shear at the tape edges. The heavier caliper of corrugated medium increases the bending stiffness difference between the unspliced web and the splice area, so full-width overlap splicing is preferred over point tabbing to distribute stress. Tape edge shear in this application is evaluated by ASTM D3654/D3654M-06 at 40 °C because roll stands without air conditioning may exceed 35 °C in summer operation. The repulpability requirement is driven by trim and rejected splices returning to the medium mill or downstream box plant pulper. Medium mills commonly screen broke through 0.20–0.25 mm slotted pressure screens; adhesive particles larger than the screen slot accumulate in rejects and can cause stickies defects in combined board. The tape is therefore specified to disperse into fragments below the screen opening under alkaline pulping conditions without requiring extended repulping time beyond the normal 20–30 minute pulper cycle.

When a Coated Fine Paper Sheeter Runs Mixed Recycle Broke

Running coated fine paper through a sheeter with mixed recycle broke creates a direct conflict between splice security and broke cleanliness. Coated fine papers in the 80–150 g/m² range are sheeted at 300–400 m/min, then cut into stacked sheets for commercial printing. The splice passes through rotary knives, slitter knives, and layboy sections; if the splice fails, the resulting web break can damage coating surfaces and generate mixed broke that includes tape, coating binders, and fiber. In mills with closed broke loops, broke is re-pulped and returned to the paper machine stock system. Coating kitchens and stock preparation areas use pressure screens with 100–150 µm slots to protect blade coaters and size presses. Undispersed adhesive from splicing tape can accumulate on these screen baskets, raise rejects, and create blade scratches on the coated sheet. The repulpability requirement in this segment is therefore more stringent than in printing grades. Laboratory screening with an ISO 5263 disintegrator and 0.15 mm slotted screen is used as a first-pass mill specification. In sheeter operations, splice overlap is kept between 20 and 40 mm for lower caliper step, while web tension at the unwind is held below 0.6 kN/m to reduce peel stress during knife changes. Published data for this specific closed-loop coated broke configuration is limited; acceptance is typically established by mill trial rather than by extrapolation from laboratory peel values alone.

At reel turn-up and core starting on paper machine winders, a strip of the R3127 single-coated tape is applied to the empty core before the sheet is transferred. The adhesive side is positioned to grip the incoming sheet at the moment of turn-up. In winders operating above 1,500 m/min, the sheet contacts the core surface with a speed differential that can momentarily exceed 100 m/min between the incoming web and the rotating core. This shock load produces a short-duration tensile spike that concentrates at the tape edge; if the adhesive has insufficient quick-stick on the core surface, the sheet can bounce and wrinkle at the core. The application width on the core is usually 6–12 mm, applied as a continuous axial strip or in segmented lengths depending on sheet caliper. A single-coated tape does not require a secondary liner removal step on the core after transfer, which reduces operator handling time on winders with multiple core stations. Core-side repulpability is still required because the tape remains on the core and enters the pulper when butt rolls or core rejects are recycled. In a mill pulper operating at 5–6 % consistency and 50–60 °C, the tape must disperse with normal broke residence time of 15–25 minutes. The primary limitation is that cores are not repulpable; the tape should not be applied in a pattern that adheres to the core surface strongly enough to tear the core surface when the sheet is unwound, because that can introduce non-repulpable core fiber fragments into the stock stream.

Sack Kraft Converting Demands a Different Shear Safety Factor

Sack kraft and envelope converting lines occupy a lower-speed segment, commonly 100–250 m/min, but they impose long-duration shear on splices because roll changes are less frequent and rewind stands may hold tension for periods exceeding 10–20 minutes. Basis weights in sack kraft range from 60 to 120 g/m², with high machine-direction tensile strength and low surface porosity compared with tissue or newsprint. The splice is made as a lap or butt splice at the unwind, then passes through flexographic print units, window-patch applicators, tube formers, and cut-off knives. Each of these stations creates a different peel angle at the tape edge, and the cumulative effect can initiate creep under sustained tension. Static shear resistance measured by ASTM D3654/D3654M-06 at 23 °C and 50 % RH is used as a screening value, but the more relevant production test is continuous tension at 35–40 °C on a roll stand with start-stop cycles. Dust from recycled sack kraft furnish can reduce initial tack, so mill practice includes air knives or brush vacuum systems at the unwind to remove surface fiber debris before tape application. Repulpability is evaluated in a mill pulper at 5 % consistency and 45–55 °C, followed by a slotted screen of 0.20 mm. Because sack kraft converting generates dry broke that is frequently recycled into high-strength furnish, any adhesive speck larger than the screen slot reduces burst strength and creates visual defects in the finished sack.