On high-output cast film lines producing machine-grade pallet wrap, Chevron Phillips 6335 LLDPE butene copolymer serves as the principal web-forming component where the published sheet density of 0.918 g/cm³ (ASTM D1505) and nominal melt-flow rate of 3.5 g/10 min (ASTM D1238) permit continuous drawdown to thicknesses of 12–30 μm at chill-roll speeds above 300 m/min. A three-layer A/B/A structure typically blends 6335 at 75–85 wt% in the skin layers and 60–70 wt% in the core, with the balance split between metallocene-catalyzed linear low-density polyethylene at 10–25 wt% and low-density polyethylene at 0–10 wt%; cling masterbatch containing polyisobutylene or similar tackifying resin is added to one skin layer at 1–3 wt%. Industrial pallet wrap is not governed by food-contact migration limits, but procurement specifications commonly reference ASTM D4649-20 and mechanical acceptance is measured by ASTM D882 for ultimate tensile, ASTM D1922 for Elmendorf tear, and ASTM D1894 for static and kinetic coefficient of friction. Melt temperatures are maintained at 245–260°C, the flat die gap is set to 0.8–1.2 mm, and edge pinning is achieved with a combination of air-knife and vacuum-box equipment; the primary chill roll is held at 18–28°C to balance web cooling with cling-agent migration. The terminal formats are pre-stretched machine film, hand pallet wrap, and lighter-gauge bundling stretch film used for unitizing pallet loads in warehousing and logistics operations. A critical processing boundary exists at the melt-temperature set point: excursions beyond ±5°C can destabilize the cling additive, causing transfer to the chill roll and increasing web-break frequency at velocities above 500 m/min.

Blown-Film Sealant Webs in Three-Layer Lamination Structures

Where the 6335 resin is converted into blown sealant webs for lamination to oriented polyester or biaxially oriented polypropylene, the butene comonomer lowers the seal initiation temperature relative to high-density polyethylene while retaining sufficient hot-tack strength for vertical form-fill-seal packaging at speeds between 40 and 80 cycles/min. The sealant layer formulation commonly uses 6335 at 70–85 wt%, low-density polyethylene at 10–20 wt%, and metallocene-catalyzed linear low-density polyethylene at 5–10 wt%; a silica-based antiblock masterbatch is introduced at 0.5–1.5 wt% and erucamide slip masterbatch at 0.2–0.5 wt% to control blocking and coefficient of friction after lamination. Food-contact compliance is evaluated under FDA 21 CFR 177.1520(c) for olefin polymers used in contact with food, and under EU Regulation No 10/2011, which specifies an overall migration limit of 10 mg/dm² for plastic materials and articles intended to come into contact with foodstuffs. The blown-film process uses coextrusion dies with diameters between 250 and 400 mm, die gaps in the 1.4–2.0 mm range, and blow-up ratios from 2.0:1 to 2.8:1; melt temperature is controlled at 190–220°C, with output from 180 to 260 kg/h depending on extruder size. The terminal forms are sealant layers in three-layer laminate structures for dry snack packaging, frozen-food pouches, and bag-in-box liners where the sealant web must remain flexible at temperatures below -20°C.

Which Barrier and Tear Properties Make Butene LLDPE Suitable for Silage Bale Wrap?

Silage bale wrap imposes simultaneous demands for high-cling, oxygen exclusion, and resistance to film puncturing from stemmy forage. In this application, 6335 is formulated at 75–90 wt% with metallocene-catalyzed polyethylene at 10–25 wt%; ultraviolet stabilizer masterbatch is added at 1–3 wt% and a carbon black or titanium dioxide masterbatch at 1–2 wt% when multi-season weathering is required. The governing product standard is EN 13207:2018, which addresses thermoplastic silage films and tubes; mechanical verification is typically done with ISO 527-3 for tensile properties of film and ASTM D1922 for tear resistance. Blown-film conversion is carried out at a blow-up ratio between 2.8:1 and 3.5:1 to impart higher TD toughness, with a die gap of 1.6–2.2 mm and melt temperature of 190–210°C; the bubble is operated in a high-stalk configuration to increase orientation before the frost line. A process conflict occurs when the frost-line height is raised more than 10 die diameters because TD elongation increases but MD tear resistance declines sufficiently to cause split propagation during bale wrapping. Finished products include round- and square-bale stretch film, silage cover sheeting, and oxygen-barrier coextruded structures used for high-moisture ensiling.

For specification alignment across the downstream application classes, the following matrix consolidates the primary regulatory frameworks and mechanical qualification methods.

At gauge ranges from 50 to 120 μm, stretch-hood pallet film produced from 6335 is formulated as a three-layer heavy-gauge blown structure in which the core layer contains 6335 at 65–80 wt% and the skin layers contain 6335 at 70–85 wt%, with the remaining fraction divided between metallocene-catalyzed polyethylene at 20–30 wt% and low-density polyethylene at 5–10 wt%; antiblock masterbatch is dosed at 0.2–0.8 wt% and slip masterbatch at 0.05–0.2 wt% in the outer skins. For industrial transport packaging, conformity is assessed under REACH 1907/2006 and packaging minimisation requirements of EU Directive 94/62/EC; mechanical lot acceptance uses ASTM D882 for ultimate tensile, ASTM D1922 for tear, and ASTM D5748 for cling between adjacent film surfaces. The blown-film line operates with a die diameter of 250–450 mm, die gap of 1.6–2.4 mm, and blow-up ratio of 2.0–2.8:1; melt temperature is held at 190–215°C, and gauge is maintained by an automatic air ring with die-bolt control to avoid thickness variation exceeding ±5%. Converters wind the output into stretch hoods for palletized cement sacks, beverage crates, and chemical bag loads, where the hood is stretched down over the load at ambient temperature. Published laboratory data for this exact stretch-hood structure is limited, but the cited processing limits are derived from commercial butene-copolymer blown-film conversion. An operational boundary appears at 6335 fractions exceeding 85 wt%, where pinhole formation at sharp package corners increases during vertical down stretching; below 60 wt%, cling force may fall below the level required for secure load retention in transit.

When Freezer-Grade Film Requires Low-Temperature Ductility Without Plasticizer Migration

Blown film used for frozen-food inner liners and ice-cream pouches is formulated without monomeric plasticizers because low-temperature flexibility is supplied by the butene comonomer in 6335 rather than by migratory additives. A monolayer or three-layer construction typically uses 6335 at 80–95 wt%, low-density polyethylene at 5–15 wt%, and a combination slip/antiblock masterbatch at 1–3 wt%; the slip agent is an erucamide or oleamide chemistry selected for controlled bloom after conversion. The structure is intended for food contact and is evaluated under FDA 21 CFR 177.1520(c) and EU Regulation No 10/2011 with an overall migration limit of 10 mg/dm²; converters may additionally reference EC 1935/2004 for general food-contact safety requirements. Processing takes place on a three-layer blown-film line with a 250–350 mm die, die gap 1.4–1.8 mm, blow-up ratio 2.0–2.5:1, and melt temperature 185–205°C; output is typically 150–250 kg/h, and the bubble is collapsed through a low-tension collapsing frame to reduce centerfold crease orientation. Finished formats include frozen vegetable pouches, ice-cream bags, and frozen meat inner liners that must survive bag-drop and rough handling at storage temperatures near -25°C. The relevant low-temperature acceptance protocol commonly includes ASTM D1709 dart-impact testing at room temperature and ISO 7765-1 free-falling dart testing on cold-conditioned specimens, because a film that passes dart impact at 23°C may still fail at freezer temperature if the blend contains excess LDPE or off-spec regrind.

At 200 μm Gauge, Fold-Crease Puncture Resistance Determines Liner Service Life

Heavy-gauge liners for flexible intermediate bulk containers and construction containment are manufactured from 6335-based blown film at thicknesses from 100 to 250 μm, where the primary failure mode is fold-crease puncture rather than tensile overload. The formulation commonly comprises 6335 at 70–90 wt%, low-density polyethylene at 5–15 wt%, recycled linear low-density polyethylene at 0–10 wt%, and calcium carbonate masterbatch at 0–8 wt% where stiffness is required; carbon black masterbatch is added at 1–2 wt% for ultraviolet resistance in outdoor exposure. Regulatory conformity for non-food industrial film is handled under REACH 1907/2006, and mechanical qualification references ASTM D1709 for dart impact, ASTM D1922 for Elmendorf tear, ASTM D5747 for puncture resistance, and ASTM D882 for tensile. The blown-film line is set with a die gap of 1.8–2.4 mm, a blow-up ratio between 2.0:1 and 3.0:1, and melt temperature 195–215°C; heavy-gauge production uses an internal bubble cooling system to manage heat removal because air-side cooling alone becomes limiting beyond 150 μm. The finished web is converted into FIBC liners, construction moisture barriers, temporary containment film, and equipment protection shrouds. A processing threshold is observed when calcium carbonate content exceeds 8 wt%, because dart-impact retention drops rapidly and fold-crease puncture resistance measured by ASTM D5747 falls below the values required for bag-drop compliance in logistics cycles.