Cast film conversion of Clearflex FG 336A at 23 µm nominal thickness exposes two process conflicts. The first is edge neck-in at the die-to-chill-roll interface. The second is draw resonance when the film is drafted above 250 m/min. The grade has a nominal melt flow rate of 3.5 g/10 min at 190°C/2.16 kg per ISO 1133-1:2022 and a nominal density of 0.922 g/cm³ per ISO 1183-1:2019.

On a 75 mm grooved-feed single-screw extruder with 30:1 L/D and a double-flight barrier section, barrel zone set points are 190°C, 210°C, 225°C, 235°C, and 240°C. The adapter and the 1,500 mm slot die are held at 240°C to 246°C. The die gap is 0.45 mm. The air gap is maintained between 38 mm and 50 mm. The primary chill roll runs at 18°C. The secondary roll runs at 22°C. Vacuum-box pressure is set from 25 mbar to 40 mbar. Air-knife pressure is adjusted until edge weave ceases.

Formulation for machine-grade pallet wrap uses 76 wt% Clearflex FG 336A, 15 wt% metallocene LLDPE with a melt flow rate of 1.0 g/10 min, and 2 wt% LDPE carrier masterbatch containing 50 wt% polyisobutylene tackifier. Slip/antiblock masterbatch at 1.0 wt% to 1.5 wt% is introduced to bring the outside coefficient of friction to 0.30–0.45 under ISO 8295. For a 23 µm machine film, stretch puncture resistance is tested under ASTM D5748. Industrial wrap lines often set an acceptance gate of 0.6 J/µm or higher. Where published datasheet data for this exact formulation is limited, incoming resin lot qualification should include a reference sample obtained under the same cast-line conditions. Neck-in increases above 250°C melt temperature. Die-lip temperature profiling may be used to compensate for edge quench. At melt temperatures above 255°C, oxidation-induced gel formation becomes visible as transparent specks in the final film.

Moisture on the pellet surface is not absorbed by the resin, but condensation on pellets stored in outdoor silos can create feed-throat melt-pressure oscillation. Pellets should be brought above dew point before conveying. The terminal product is machine pallet wrap supplied in 450 mm to 500 mm roll widths, calendered onto 76 mm paper cores. For EU export, the finished stretch film is within the scope of 94/62/EC for heavy metals. The sum of lead, cadmium, mercury, and hexavalent chromium must not exceed 100 mg/kg by acid digestion and ICP-OES.

What Melt Pressure and Bubble Cooling Parameters Govern Heavy-Duty Sack Down-Gauging?

At 70 µm film thickness, heavy-duty sack production on three-layer blown-film equipment demands a balance between dart impact, Elmendorf tear, and bubble stability. A form-fill-seal sack structure commonly uses 30 wt% Clearflex FG 336A in the outer layer, 40 wt% in the core, and 30 wt% in the inner layer. LDPE with a melt flow rate of 0.3 g/10 min is added at 20 wt% to improve melt strength. High-density polyethylene with a melt flow rate of 0.1 g/10 min is added at 10 wt% for stiffness and downgauging. A post-industrial recycled LLDPE fraction in the core layer should not exceed 15 wt%. Its melt flow rate should not deviate by more than ±20% from the virgin Clearflex FG 336A value.

On an 80 mm grooved-feed extruder with 30:1 L/D and a 250 mm spiral mandrel die, the die gap is set at 2.2 mm. The blow-up ratio is held between 2.5:1 and 2.8:1. The frost-line height is maintained at 7 to 9 die diameters. Melt temperature at the die is kept between 200°C and 210°C. Screen-changer melt pressure is typically observed in the 350 bar to 420 bar range before the gear pump. A pressure rise greater than 25% at constant output signals gel build-up and requires a screen change.

Bubble stability is the principal conflict. Linear low-density polyethylene has lower melt tension than the LDPE fraction. Setting the frost-line height too high produces a soft bubble that sways. Setting it too low reduces machine-direction tear. A lay-flat width variation greater than ±5 mm across the bubble circumference indicates uneven cooling. Dual-lip air rings with lower-lip velocity 25% higher than upper-lip velocity are used on high-output lines. At these conditions, the 70 µm heavy-duty sack should meet a dart-drop F50 value of at least 500 g under ASTM D1709. Elmendorf tear is measured under ISO 6383-2. Machine-direction tear is limiting in form-fill-seal service. Increasing blow-up ratio above 2.8:1 improves transverse-direction tear but reduces machine-direction tear and destabilises the bubble. Do not pre-dry below 60% relative humidity. At higher humidity, condensation on the pellet surface must be eliminated with hopper-carrier air above dew point. The terminal product is a 70 µm heavy-duty sack for 50 kg polymer granule packaging.

Agricultural bale wrap produced at 25 µm thickness from Clearflex FG 336A is typically run as a cast coextruded structure. The outer layer is formulated at 12 wt% of total thickness. The core layer is 68 wt%. The inner layer is 20 wt%. The outer layer contains 4 wt% of a UV masterbatch based on 20 wt% hindered amine light stabiliser and 10 wt% carbon black in LDPE. The outer layer also contains 2 wt% polyisobutylene masterbatch for cling. The inner layer contains 1.5 wt% of a slip/antiblock masterbatch to control blocking on the unwind path.

On a 70 mm 24:1 L/D cast-line extruder with a 1,200 mm slot die, the die gap is set at 0.35 mm. Melt temperature is 235°C. Chill roll temperature is 20°C. Line speed is held near 600 m/min. Edge trim is kept below 8% of web width. Ageing resistance is evaluated under ISO 4892-2 using a UVA-340 lamp. A common silage-wrap acceptance target is retention of at least 50% tensile elongation after 2,000 h. Tensile elongation is measured under ISO 527-3. Tear propagation resistance is measured under ISO 6383-2. The product must satisfy EN 13206 for thermoplastic stretch films used to wrap silage bales. Published data for this specific three-layer structure is limited. Resin lots with a melt flow rate outside ±10% of nominal can shift cling uniformity and should be controlled. The terminal product is a 750 mm wide, 1,500 m long roll of 25 µm silage bale wrap.

When Clearflex FG 336 A Is Used as a Sealant Layer Beneath EVOH Barrier Webs

Five-layer coextruded barrier packaging for processed meat makes the sealant web the controlling factor for both heat-seal integrity and migration compliance. The structure is typically 20 µm LDPE / 3 µm maleic anhydride grafted tie / 5 µm EVOH / 3 µm tie / 40 µm sealant. The sealant layer is compounded from 75 wt% Clearflex FG 336A and 25 wt% LDPE with a melt flow rate of 0.3 g/10 min. A slip/antiblock masterbatch is added at 1.5 wt%. The sealant melt temperature at the die is held at 205°C to 215°C. The die gap is 1.8 mm. The blow-up ratio is 2.0:1. The frost-line height is 4 to 5 die diameters. EVOH degradation is avoided by keeping the barrier-layer melt below 230°C.

Differential scanning calorimetry of Clearflex FG 336A per ISO 11357-3 shows a melting peak in the 121°C to 126°C range. Heat-seal strength is tested under ASTM F88 with a 25 mm wide specimen, 0.28 MPa jaw pressure, and 0.5 s dwell. At a seal bar temperature of 130°C, the sealant web should exceed 12 N/25 mm on a 40 µm sealant layer. For migration compliance, the finished structure is tested under EU No 10/2011. Overall migration must remain below 10 mg/dm² in food simulant A, B, or D2 depending on intended food type. The resin must comply with FDA 21 CFR 177.1520 paragraph 3.1a for olefin polymers. Additives must be verified against the positive lists in EU No 10/2011 Annex I.

The terminal product is a 40 µm sealant web used in form-fill-seal pouches for processed meat and cheese. Corona treatment of the outer LDPE side to 42 mN/m is performed in-line for lamination adhesion.

E-commerce Mailer Film Puncture Resistance and Seal Integrity

Producing e-commerce mailer film at 55 µm monolayer thickness from Clearflex FG 336A requires simultaneous control of puncture resistance during sortation and tear initiation during manual opening. The formulation comprises 70 wt% Clearflex FG 336A, 20 wt% LDPE with a melt flow rate of 0.30 g/10 min, and 10 wt% white masterbatch containing 60 wt% titanium dioxide in LDPE. Erucamide slip active is added at 300 ppm to 600 ppm. Synthetic silica antiblock is added at 1,500 ppm. On a 65 mm 28:1 L/D single-screw extruder with a 150 mm die, the die gap is set at 1.5 mm. The blow-up ratio is held at 2.8:1. The frost-line height is 5 die diameters. Melt temperature is maintained between 190°C and 205°C.

Dart-drop impact is tested under ASTM D1709. Industrial acceptance for a 55 µm e-commerce mailer often requires F50 ≥ 250 g. Puncture propagation is screened by ASTM D5748. Seal strength is measured under ASTM F88 at 0.28 MPa and 0.5 s. The seal should reach 10 N/25 mm at 130°C. If seal strength exceeds 15 N/25 mm, the mailer may fail opening-preference tests because tear initiation at the laser score becomes inconsistent. Corona treatment for printing is set to 40 mN/m. The terminal product is a tamper-evident mailer bag with a pressure-sensitive closure tape.

Frozen-food lamination web at 40 µm is produced as a monolayer blown film with 20 wt% LDPE to reduce heat-seal initiation. Pre-drying is not required below 60% relative humidity. Corona treatment to 42 mN/m is applied before lamination with solventless polyurethane adhesives.