3M™ Splicing Tape 9464 is a carrierless high-shear acrylic pressure-sensitive adhesive transfer film supplied on a 60 lb densified kraft release liner. The adhesive layer has a nominal thickness of 4.0 mil (0.10 mm), and the liner is silicone-coated on both faces to permit kiss-cut pre-splicing and clean removal in automated splicing stations. Standard master-roll geometry is 60 in × 144 yd (1.52 m × 131.7 m), with slit widths produced for turret rewinders, flexographic presses, sheeters, and laminating lines. The product is designed for butt-splicing and overlap-splicing of release-coated liners, low-surface-energy films, paper, and foil. The manufacturer’s published intermittent service temperature range is -40°C to 149°C. ASTM D3330/D3330M-04 may be used to compare 180° peel adhesion on stainless steel; stainless steel values do not predict performance on silicone-coated grades because release coatings vary in crosslink density, release force, and silicone migration. Published peel data for this specific configuration on silicone-coated liner is limited, and controlled splice trials on the actual release system are required before production use.

Because the tape is carrierless, splice thickness is limited to the adhesive caliper. This reduces the ridge that can mark substrates in high-precision printing or coating and permits the splice to conform to liner wrinkles and minor roll-surface irregularities without polyester-carrier springback. The trade-off is the absence of a reinforcing film; splice strength is therefore controlled by the cohesive strength of the acrylic layer rather than by carrier tensile strength. ASTM D3759/D3759M-05 is applicable to carrier-backed tapes and is not directly used for unsupported transfer films; tensile evaluation of unsupported adhesive is typically reported from film-cast specimens rather than finished tape.

What Governs Splice Integrity on Silicone-Coated Release Liners?

Adhesion on silicone-coated liners depends on wet-out, dwell, and pressure. Silicone release surfaces generally present surface energy in the 20–24 mN/m range, which is below the surface energy of many pressure-sensitive adhesives. The high-shear acrylic used in 9464 is formulated to wet release-coated paper and film surfaces while retaining creep resistance under web tension. Production splicing is normally performed under a nip roll at 0.2–0.4 MPa (30–60 psi). After the liner is removed, the exposed adhesive is joined to the second web, and the splice should not be exposed to full line tension until 5–10 min of dwell has elapsed. Edge lifting on silicone-coated liners is most often associated with insufficient nip pressure, silicone fluid migration from the release surface, or application below 10°C.

On zero-speed splicers, the tape is pre-applied to the tail of the expiring roll and kiss-cut to remove the liner in the splice zone. The exposed adhesive is protected until the splice head closes. The process is sensitive to liner curl; if the densified kraft liner curls, kiss-cut registration can shift and produce exposed adhesive outside the splice area. Storage at 21°C and 50% RH is recommended. Moisture-stabilized liner reduces curl in automatic splicing equipment. If liner curl is observed after storage, 24 h conditioning at 21°C and 50% RH before kiss-cutting is a common corrective step.

Low-surface-energy polyethylene and polypropylene webs often exhibit surface energy below 30 mN/m. If 9464 is applied without corona pre-treatment, initial tack may be adequate for stationary handling but marginal under acceleration. Corona discharge treatment to 38–42 mN/m immediately before splicing improves wet-out and peel strength. Because corona treatment decays with time, in-line treatment or treatment within 24 h of splicing is preferred. For fluoropolymer webs, chemical etching with sodium naphthalenide or equivalent is required; unprimed PTFE and FEP surfaces are not recommended for acrylic splicing without aggressive surface modification.

Nominal Construction and Handling Parameters

In flexographic label converting, a common splice procedure uses a straight or chevron tail. 9464 is applied to the new roll tail with a 0.2–0.4 MPa nip, the liner is removed, and the tail is joined to the expiring web. The splice is burnished across the full width before the press is jogged. The press should not be accelerated until the splice has passed through one draw section. If edge lifting occurs during acceleration, the cause is usually insufficient dwell, liner contamination, or excessive web tension rather than a deficiency in the acrylic layer itself.

When Elevated Drying or Vulcanizing Temperatures Are Present

Some converting and coating lines carry splices through heated dryers or curing tunnels. The acrylic adhesive transitions from elastic to viscoelastic behavior as temperature rises. At the upper intermittent limit of 149°C, exposure is acceptable only when the splice is under low tension. Continuous exposure above 149°C can lead to cohesive failure because the adhesive no longer behaves as an elastic solid. Silicone-adhesive splicing tapes may offer higher thermal stability but can introduce silicone contamination into downstream coating or painting operations. Selection of 9464 in heated processes is therefore a balance between contamination control and the temperature ceiling of acrylic chemistry.

Adhesive transfer tapes are not suitable for splicing highly plasticized vinyl, unprimed fluoropolymer films, or substrates containing migratory slip agents such as stearamide or erucamide. Such additives can migrate into the acrylic layer within 48 h and reduce peel adhesion. Solvent pre-cleaning with isopropanol or heptane should be followed by complete evaporation before splicing; chlorinated solvents and ketones may soften the acrylic polymer and must not remain on the web at the splice point. Condensation on chilled webs below dew point also inhibits wet-out, so splice stations in high-humidity environments should be protected from moisture accumulation.

Differences Between 9464 and Related Transfer-Tape Splicing Grades

Compared with 9460, the 4.0 mil 9464 layer provides better gap-filling across butt joints and higher stress distribution on rough or embossed webs; however, it adds caliper and may create a visible step in thin-film winding. Compared with 9472, 9464 prioritizes shear resistance over immediate tack to low-energy surfaces; 9472 may be selected where fast wet-out to contaminated films is more critical than elevated-temperature creep resistance. Compared with polyester-backed splicing tapes, 9464 eliminates carrier-induced springback but provides no reinforcing film across wide splice gaps. Web tension must therefore remain within the cohesive strength of the unsupported adhesive.

When comparative bond data is generated, ASTM D3330/D3330M-04 Test Method A is used for 180° peel on stainless steel. Static shear is evaluated under ASTM D3654/D3654M-06 Procedure A using a 1 kg load. These values are comparative and do not establish performance on silicone-coated paper liners. Qualification of 9464 on silicone release liners requires controlled splice trials on the actual release formulation, including silicone cure chemistry, release force, and downstream storage conditions.

Regulatory status depends on converting condition and end-use. Under EU REACH, the supplied article may contain substances above reporting thresholds; current SVHC lists must be checked. EU RoHS 2011/65/EU applies only to electrical and electronic equipment and not to all splicing applications. Where indirect food contact is claimed, the application must be evaluated under 21 CFR 175.105 or equivalent national legislation. No blanket food-contact compliance is implied for 9464, and current supplier certifications should be obtained for each lot.

Lot-to-lot variation in liner release and adhesive firmness can shift kiss-cut depth and splice peel. A change in adhesive lot, liner lot, or converting humidity outside 35–65% RH should trigger a reduced-speed trial on the target splicer. If peel values from stainless steel differ significantly from the established baseline, the root cause is often liner contamination or aging rather than the adhesive lot alone. In sheeting operations, overlap splices made with 9464 should be arranged so that exposed adhesive is not passed through hot calender rolls or coating heads, because acrylic mass transfer to process rolls can occur at elevated temperature.