On blown-film lines configured for heavy-duty industrial shipping sacks, Chevron Phillips 6109K—a butene-copolymer linear low-density polyethylene with nominal density 0.922 g/cm³ and melt index 0.9 g/10 min at 190 °C/2.16 kg—is processed into monolayer and coextruded sack film at die gaps between 1.8 mm and 2.2 mm. In converter trials, a 70–85 wt% loading of 6109K blended with 15–30 wt% low-density polyethylene is used to raise bubble stability because the low melt strength of the butene copolymer at blow-up ratios above 2.8 can cause fluctuation in frost line height and gauge variation. At film thickness from 120 µm to 200 µm, the addition of 1.0–2.5 phr slip/antiblock masterbatch is applied for controlled coefficient of friction, while 0.3–0.8 phr fluoropolymer processing aid is used to postpone melt fracture on 50 mm grooved-feed extruders with L/D ratios of 30:1.

Compliance for non-food industrial sacks is anchored to ASTM D1709-16a for dart impact, ASTM D1922-15 for Elmendorf tear propagation, and ISO 527-3:2018 for tensile properties, with incoming resin tested per ASTM D1238-20 for melt flow rate and ASTM D1505-18 for density. Where sacks are used for dangerous goods packaging, drop and stack stability are evaluated under the UN Manual of Tests and Criteria rather than resin-level food-contact standards. Extrusion of 6109K on a 65–90 mm barrier screw at 190–220 °C, with die diameter 250–400 mm and blow-up ratio 2.2–2.8, yields film output of 150–220 kg/h; frost line height is maintained at 6–8 die diameters to balance machine-direction/transverse-direction orientation. The bubble is collapsed through a slatted collapsing frame and gusseted to produce flat or gusseted tubing. After surface treatment to 38–42 mN/m dyne level, the film is converted on side-seal or bottom-seal sack machines.

Compliance matrix for heavy-duty non-food industrial sack film:

Finished formats include FIBC liners, heavy-duty valve sacks, asphalt and chemical shipping sacks, and pallet hoods. 6109K alone without LDPE has insufficient bubble stability at blow-up ratio above 3.0, and at film gauges below 30 µm the butene branch architecture produces lower tear resistance than hexene- or octene-copolymer LLDPE grades; thin-gauge applications below that boundary are excluded from this scenario.

What Limits the Frost Line Height Range in Frozen Food Lamination-Grade Monolayers?

Frozen food lamination-grade films produced with 6109K must satisfy EU Regulation No 10/2011 for overall migration below 10 mg/dm² and specific migration limits for butene-derived oligomers, while FDA 21 CFR §177.1520 applies for olefin polymers in contact with aqueous and fatty foods at low temperatures. The resin is formulated at 60–80 wt% with 20–40 wt% of a 0.918 g/cm³ LDPE or metallocene LLDPE in the core layer of a three-layer A/B/A coextrusion, with 1.0–2.0 phr antiblock masterbatch and 0.5–1.0 phr slip masterbatch in the skin layers. The processing window on a 3-layer blown-film line with a 350 mm die, 1.5 mm die gap, and blow-up ratio 2.0–2.5 requires melt temperature 200–225 °C; if frost line height is set below 4 die diameters, bubble instability and blocking occur. Published converter data for the specific 6109K grade at this exact multilayer structure is limited; the seal range cited is the observed window on a 3-layer line processing a 0.922 g/cm³ butene copolymer. Side-seal jaw temperatures between 95 °C and 110 °C at 0.5 s dwell produce acceptable seal strength, but heat seal initiation is slower than for hexene or octene copolymers at the same density.

On a production 3-layer line, a repeated failure mode is film blocking on the collapsing frame when internal bubble cooling air temperature drops below 15 °C and ambient humidity exceeds 60% RH due to condensation on the film surface. The extruder configuration uses 50–70 mm grooved-feed screws with L/D 30:1 and a 400 mm die; output is held at 180–250 kg/h to prevent frost line movement. Terminal products include bags for frozen vegetables, seafood pouches, pre-formed pouch stock, and ice cream packaging. This structure is not used for boil-in-bag or retort applications because the butene copolymer seal layer lacks sustained hot-tack above 110 °C.

Where silage pile covers must withstand UV exposure for 18–24 months, 6109K is blended with 5–15 wt% of a 0.924 g/cm³ low-density polyethylene or a C6 linear low-density polyethylene to improve melt strength during bubble formation at blow-up ratios of 2.0–2.6. The formulation includes 2–5 phr HALS-based UV stabilizer masterbatch and, for black or white films, 3–6 phr carbon black or titanium dioxide masterbatch. Compliance for agricultural cover films is governed by EN 13206:2017; oxygen barrier claims are not made for monolayer polyethylene because oxygen transmission measured per ASTM D3985-17 remains above the threshold required for silage fermentation control, so coextrusion with EVOH or polyamide is required where oxygen barrier is specified. REACH Annex XVII restricts cadmium-based pigments and certain phthalate plasticizers in these formulations.

Extrusion of silage cover film uses a 2.0–2.4 mm die gap, melt temperature 190–220 °C, and blow-up ratio 2.0–2.6; film thickness ranges from 25 µm for low-tunnel covers to 150 µm for silage pit covers. On a 90 mm barrier-screw extruder with L/D 30:1 and a 400 mm die, output rates of 300–400 kg/h are achievable, but the addition of UV stabilizer masterbatches reduces melt strength and requires frost line height to be lowered by 1–2 die diameters relative to unstabilized film. Terminal product types include clamp silage covers, ensilage pit liners, low-tunnel greenhouse films, and mulch film substrates. Without adequate UV stabilization, the film embrittles after a single season; 6109K should not be specified for long-term exterior geomembrane or pond-liner service.

Stretch Hooder Film and the Thickness Uniformity Threshold on Rotating-Die Blown Lines

On stretch hooder pallet-load containment equipment, 6109K is extruded as 80–120 µm monolayer blown film where thickness uniformity across the bubble must remain within ±4% to prevent uneven stretching around pallet corners. The formulation is 85–95 wt% 6109K with 5–15 wt% LDPE to raise melt strength, plus 0.5–1.0 phr slip/antiblock masterbatch and 0.5–1.5 phr UV stabilizer masterbatch for outdoor pallet storage. Compliance for mechanical properties follows ASTM D882-18 for tensile, ASTM D1709-16a for dart impact, and ASTM D1922-15 for tear propagation, with density and melt flow rate checked per ASTM D1505-18 and ASTM D1238-20.

Blown-film processing uses a rotating die with diameter 400–600 mm, die gap 2.0–2.2 mm, blow-up ratio 2.0–2.5, and melt temperature 200–230 °C. The die rotates at 0.5–1.0 rpm to randomize gauge bands; output on a 90 mm extruder with L/D 30:1 is held at 180–250 kg/h. Terminal products include industrial pallet hooder film, protective film for tall palletized loads, and outdoor storage covers. Operational boundary: at film thickness below 60 µm, the film has insufficient tear resistance at pallet corners during high-speed hooder application.

Because dry food and detergent pouches require a sealant web that seals at 105–120 °C at 0.5 s without distorting printed PET outer layers, 6109K is extruded as a 15–30 µm sealant web on tandem extrusion lamination lines; the resin component is used at 100 parts per hundred resin, with 1.0–2.0 phr antiblock masterbatch and 0.5–1.0 phr slip masterbatch because a laminating adhesive bonds to the corona-treated surface at 38–42 mN/m. Lamination-grade film compliance follows EU Regulation No 10/2011 for overall migration and FDA 21 CFR §177.1520 for olefin polymers; the adhesive system must independently comply with 21 CFR §175.105. Blown-film processing on a 1.5–2.0 mm die gap, blow-up ratio 2.0–2.5, and melt temperature 190–225 °C is used before adhesive lamination to BOPP, PET, or metallized PET. The low seal initiation of butene LLDPE minimizes deformation of the printed substrate during sealing.

The production limitation is that 6109K exhibits limited hot tack above 110 °C compared with octene-based grades, causing seal creep during vertical form-fill-seal at speeds above 60 packs/min; converters often blend 20–30 wt% metallocene LLDPE for hot tack. Terminal product types include stand-up pouches, detergent sachets, dry mix pouches, and snack packaging. Excessive slip additive above 1500 ppm erucamide is avoided because migration to the adhesive interface reduces laminate bond strength.

When Temporary Construction Vapor Barriers Must Outperform Standard LDPE in Dart Drop Resistance

Temporary construction vapor retarder films made from 6109K are used where ASTM E1745-17 Class A requires water vapor permeance below 0.1 US perms. The film is extruded as a monolayer at 150–250 µm thickness with 2.0–2.5 phr carbon black masterbatch and 1.0–2.0 phr processing antioxidant masterbatch. Formulation is 95–100 wt% 6109K; up to 5 wt% LDPE is added to raise melt strength at thick gauge. Processing uses blown-film extrusion with a 2.4 mm die gap, blow-up ratio 1.8–2.2, melt temperature 200–230 °C, and high-capacity air ring cooling. Water vapor permeance is measured per ASTM E96/E96M-16 desiccant method, and dart impact per ASTM D1709-16a.

Production-scale observations on 90 mm extruders with L/D 30:1 show that output is reduced by 30–40% relative to 50 µm film at the same melt temperature because thick-gauge bubble cooling becomes the limiting factor. The bubble collapse and flattening section must use rollers set below 40 °C to avoid blocking. Terminal products include crawl space vapor barriers, temporary floor protection films, concrete curing covers, and below-slab moisture barriers. 6109K is not suitable for permanent below-grade waterproofing membranes where hot-welded seams and long-term hydrostatic resistance are specified; those applications require HDPE or composite membranes.