SABIC LLDPE 118WS is charged to mono-layer blown film extrusion lines as a butene-based linear low-density polyethylene with a nominal density of 0.918 g/cm³ measured by ISO 1183-1 and a melt flow rate of 1.0 g/10 min under ISO 1133-1:2022 condition 190 °C/2.16 kg. The slip/antiblock system in the grade produces a time-dependent amide bloom; film-to-film coefficient of friction, evaluated by ASTM D1894, is not stable immediately after winding and commonly requires 24 h to 72 h storage at 20–25 °C before bag conversion lines achieve consistent feeding. High-speed bag machines operating at 200–250 strokes/min on 25–40 µm film show that skip welding and blocking are more frequent when rolls are processed within the first 12 h after extrusion. The formulation for retail carrier sacks is either 100 wt% 118WS for gauges down to 20 µm, or 70 wt% 118WS blended with 30 wt% cleaned post-industrial LLDPE recyclate. Recyclate content above 30 wt% narrows the bubble stability window and increases dart impact variability. Extrusion is performed on grooved-feed single-screw machines with 30:1 to 40:1 L/D barrier screws; rear barrel zones are set at 160–175 °C, middle zones at 190–205 °C, and the die body at 205–215 °C. Melt temperature at the adapter should not exceed 220 °C because higher thermal exposure reduces slip additive effectiveness through volatilization and oxidation. The die gap is set between 1.4 mm and 1.8 mm, the blow-up ratio between 2.2:1 and 2.6:1, and the frost line height between 4 and 6 die diameters. No predrying is normally required because polyethylene is non-hygroscopic; if resin bags are stored at relative humidity above 60%, surface condensation should be avoided by conditioning the silo to ambient temperature before line charging. On a 100 mm annular die without external bubble cooling, stable output is generally limited to 0.30 kg/h per mm of die circumference; exceeding this threshold generates gauge bands and bubble flutter, particularly when ambient air temperature varies by more than 5 °C during a shift. End-product carrier sacks are sealed by side-weld or bottom-seal conversion; for 25 µm film, the target dart impact using ASTM D1709 Method A is generally above 60 g, but published grade-specific values remain limited. Packaging compliance for non-food retail sacks falls within EU Directive 94/62/EC Article 11, where the combined concentration of lead, cadmium, mercury, and hexavalent chromium must not exceed 100 mg/kg; REACH SVHC notification at 0.1 wt% is not triggered by the base resin but must be re-evaluated when recycled content is introduced.

What Hot-Tack Window Is Maintained When 118WS Is Extruded as a 20 µm Sealant Layer in PET/LLDPE Laminates?

In extrusion lamination and cast coextrusion for flexible packaging, SABIC LLDPE 118WS is used as a sealant skin because butene-based linear low-density polyethylene initiates seal strength at lower temperatures than polypropylene or high-density grades. In a PET/118WS laminate intended for vertical form-fill-seal machines, the sealant web is extruded at 20–35 µm thickness, with a typical weight share of 100% 118WS in the sealing layer. The heat-seal initiation temperature measured on a laboratory heat sealer according to ASTM F2029 is commonly observed between 90 °C and 105 °C, while the plateau seal strength from 105 °C to 125 °C generally remains above 1.5 N/25 mm under a 300 mm/min peel speed per ASTM F88. Hot-tack testing per ASTM F1921 indicates a usable hot-tack window above 1.2 N/25 mm from 100 °C to 120 °C, which is adequate for high-speed pouch lines operating at 40–60 cycles/min. The incorporated slip additive migrates to the sealant surface and can reduce coefficient of friction; however, it also deposits on seal jaws and can alter heat transfer, so jaw release temperature must be controlled and jaw surfaces inspected every 4–6 h of continuous operation. Extrusion lamination is carried out on single-screw extruders with 25:1–30:1 L/D, melt temperature at 200–215 °C, and an air gap of 120–180 mm between die and nip; the chill roll is held at 15–20 °C to limit post-crystallization haze. Food-contact compliance follows EU Regulation 10/2011, with an overall migration limit of 10 mg/dm² under the assigned food simulant; the base resin position within 21 CFR 177.1520(c) must be confirmed by the converter through supplier documentation because the exact additive package and any intended contact with aqueous, fatty, or dry food simulants determine end-use status. The terminal structure is employed in dry food pouches, frozen condiment sachets, and medical device overwrap where low seal initiation is critical. The boundary for the sealant layer is retort packaging: above 121 °C, the butene LLDPE sealant softens and heat-seal strength falls sharply; published data for this specific configuration under retort conditions is limited.

Single-ply heavy-duty sacks carrying 25–50 kg of polymer pellets, granular fertilizer, or petrochemical resin are extruded from a blend of 80 wt% SABIC LLDPE 118WS and 20 wt% high-pressure LDPE. The LDPE addition increases melt tension in the bubble and suppresses long-neck instability that otherwise appears at blow-up ratios above 2.5:1 on 150 mm annular dies. Films are produced at 120–180 µm thickness with a die gap of 1.8 mm to 2.0 mm, a blow-up ratio of 2.2:1 to 2.8:1, and a frost line height maintained between 6 and 8 die diameters. Internal bubble cooling is generally required above 0.35 kg/h per mm of die circumference; without IBC, bubble flutter narrows the operating window and increases gauge variation beyond the ±5% alarm limit. The key performance requirement is dart impact after filling and drop testing. Filled sacks are conditioned at 23 ± 2 °C and dropped from 1.2 m onto a concrete floor according to ASTM D5276; pass criteria are agreed between converter and end user, but a widely used acceptance limit for a 25 kg filled sack is no leakage and no seal failure after three vertical drops. For dangerous goods packaging, type approval requires additional testing under the UN Manual of Tests and Criteria, Part III, including drop and stack testing on packaging intended for transport. The base 118WS contributes low-temperature toughness in cold-drop programs at -18 °C; however, stress-crack resistance is lower than octene-based LLDPE, so a converter must not assume parity in aggressive wetting environments. The slip/antiblock system is a processing constraint in heavy-duty sack printing: high slip bloom reduces ink adhesion if corona treatment is below 38 mN/m; the film should be treated in-line and printed within 48 h to limit surface re-bloom. End-product sacks are stitched or heat-sealed at the bottom; a bottom-gusset design with 100–150 µm film lowers stress concentration at the seam. Puncture resistance measured by ASTM D3420 Procedure A is monitored for lot consistency, but published grade-specific data for this configuration remains limited.

Drum liners require stress-crack resistance after contact with alkyl sulfates

Industrial drum liners produced from SABIC LLDPE 118WS are extruded as tubular blown film with a diameter sized to fit 208 L steel or plastic drums. The recommended thickness for chemical powder and non-oxidizing liquid service is 100–125 µm. The process uses a die gap of 1.6–2.0 mm, a blow-up ratio of 1.5:1 to 2.0:1, and lower screw speeds than carrier bag film to limit melt temperature to 190–205 °C. In a 208 L drum liner, environmental stress-crack resistance is the controlling mechanical property rather than dart impact. ESCR is measured according to ASTM D1693 Condition A at 50 °C in 100% Igepal CO-630; butene-based LLDPE typically fails earlier than octene-based LLDPE under the same stress-crack test, so liner thickness may need to be increased by approximately 10–20% for service with alkaline cleaners or wetting agents. The specific failure mode observed on production-scale lines is circumferential splitting at the bottom fold after the liner has been in contact with surfactant-containing liquids for 30–90 days; this is accelerated when the liner is folded along the same crease repeatedly during storage. The film tube is cut to length and bottom-sealed by impulse welding; seal integrity is checked by air-immersion testing at 1.5–2.0 psi in a water bath, with no bubbling allowed for 30 s. Compliance for chemical containment is product-specific and requires end-user compatibility testing with the actual fill product, especially for ketones, aromatic hydrocarbons, and strong oxidizing acids at temperatures above 40 °C. The base resin itself is not a replacement for a UN-certified inner packaging component; UN certification for dangerous goods is required when the filled drum assembly is offered for regulated transport. Terminal applications include liners for resins, pigments, food powders, and non-aggressive liquid detergents. The grade is not suitable for prolonged contact with concentrated nitric acid or chlorinated solvents at elevated temperature because permeation and stress cracking become severe.

When butene LLDPE is coextruded as an inner seal layer in pet food pouches

In five-layer blown film structures for dry pet food pouches, SABIC LLDPE 118WS is employed as the innermost heat-seal layer at 15–20 wt% of total throughput. The full structure is typically a high-density core with a barrier polymer such as EVOH; layer order is outer LLDPE/LDPE, adhesive tie, EVOH, adhesive tie, sealant. The use of 118WS in the sealant layer enables a low seal initiation range of 90–105 °C on vertical form-fill-seal equipment with 1.2–1.5 N/25 mm seal strength according to ASTM F88. Extrusion must respect EVOH thermal limits; the maximum melt temperature for the coextrusion block is normally held at 210–220 °C because EVOH decomposition accelerates above 230 °C and forms oxidized amber specks. The screw configuration for the sealant layer is a 30:1 L/D barrier screw with a low-shear Maddock mixing section; if a high-shear mixer is used, melt temperature in the LLDPE layer can exceed the desired limit and cause gel formation. The blow-up ratio is kept at 2.0:1 to 2.5:1, the die gap at 1.8–2.2 mm, and the total film thickness at 60–90 µm for pet food pouches with side gussets. Slip migration from the sealant layer can reduce film-to-film friction for pouch opening, but it also can interfere with corona treatment of the outer layer if the web is stored for more than 48 h; inline treatment is preferred. Compliance for food-contact packaging follows 21 CFR 177.1520(c) for the olefin polymer, 21 CFR 177.1360 for EVOH, and EU Regulation 10/2011 with an overall migration limit of 10 mg/dm². The terminal product is a dry pet food pouch with gas-flushed headspace; the sealant layer must maintain seal continuity through the gusset transition, which is the primary source of leak failures at production speeds above 50 packs/min. Published data for this specific barrier configuration using 118WS is limited, so initial seal-temperature mapping is required.

Collation shrink film for bottled beverage multipacks uses SABIC LLDPE 118WS in blends to balance shrink force and seal robustness. A practical formulation on standard three-layer blown film lines is 75 wt% 118WS and 25 wt% high-pressure LDPE or an ethylene-vinyl acetate grade with 18% vinyl acetate to elevate shrink force. The built-in slip/antiblock system in 118WS is normally sufficient; if film-to-film coefficient of friction remains above 0.30 after 72 h, a converter may introduce 2–4 wt% synthetic silica anti-block masterbatch. The film is extruded at 60–100 µm thickness with a die gap of 1.6–2.0 mm and a blow-up ratio of 2.8:1 to 3.2:1 to create preferred MD/TD orientation balance. The primary process bottleneck is shrink force: butene LLDPE generates lower shrink tension than octene LLDPE at equivalent thickness, so the converter compensates by reducing the frost line height and increasing the stretch ratio in the machine direction during secondary orientation. On shrink tunnels operating at 140–160 °C air temperature with 3–5 s residence time, the film must conform to bottle tops and bottom tray edges without causing board distortion. Film-to-machine friction is controlled through the slip additive, but excessive slip can increase film roll telescoping during storage. Heavy metals and packaging compliance follow EU Directive 94/62/EC; if the multipacks are exported to U.S. states that follow CONEG model legislation, the sum of lead, cadmium, mercury, and hexavalent chromium in packaging must not exceed 100 mg/kg. Terminal use is a printed collation film that is perforated for easy opening; perforation tear propagation is evaluated by ASTM D1922 Elmendorf tear, with MD/TD tear balance adjusted via blow-up ratio. Published data for this specific collation shrink configuration is limited; practical qualification includes seal curve mapping and tunnel shrinkage trials.

Low-temperature dart impact in frozen food packaging film

At freezer storage temperatures, frozen food packaging film produced with SABIC LLDPE 118WS retains dart impact because the butene comonomer linear low-density structure delays brittle fracture. The film is blown at 40–70 µm thickness and used as a mono-layer or as the sealant layer in a three-layer coextrusion. A typical formulation is 85 wt% 118WS with 15 wt% LDPE for deeper draw on horizontal form-fill-seal machines; for pillow pouches on vertical machines, 100% 118WS is used to maximize seal integrity at the longitudinal and cross-seal intersection. Processing conditions require a die gap of 1.4–1.8 mm, blow-up ratio of 2.0:1 to 2.5:1, and a frost line height between 4 and 5 die diameters to retain impact strength; an excessively high frost line increases crystalline orientation and reduces low-temperature dart impact. The critical test is dart impact at -25 °C after 48 h conditioning according to ASTM D1709 Method A; converted films should not exhibit complete brittle failure at 50 µm thickness, but the exact dart value is end-use specification-dependent. Cold-temperature seal strength is tested after water immersion from 0 °C to 5 °C using ASTM F88; seal strength loss is typically less than 10% compared with 23 °C, provided the cross-seal jaws are set to a dwell time of 0.3–0.5 s and temperature of 105–115 °C. Food-contact compliance for frozen food under EU law requires Regulation (EC) 1935/2004 and EU Regulation 10/2011, with the understanding that frozen food is tested under reduced time-temperature conditions; FDA compliance for the base olefin polymer falls under 21 CFR 177.1520(c). The terminal products are vegetable pouches, ice cream bags, and frozen ready-meal film; the operational boundary is that the film should not be used for products that are microwaved in-package above 100 °C, because butene LLDPE softens and may deform. Published data for this specific grade at -25 °C remains limited, so converters must generate in-house low-temperature dart impact data for their specific gauge and BUR.