Blown film conversion for T-shirt carrier bags is performed on single-screw extruders with L/D ratios between 25:1 and 30:1. The screw employs a barrier flight section and a Maddock mixing element. Melt temperature at the die exit is held between 190°C and 220°C. The die is a spiral mandrel type with an annular gap of 1.2 mm to 1.6 mm. The bubble is operated in the stalk configuration. Frost line height is maintained between 6 and 12 die diameters above the die face. Blow-up ratio is set from 3:1 to 4:1. Film thickness between 10 µm and 20 µm is achievable with Versalis HDPE FC 82. Tensile properties are measured per ASTM D882. Secant modulus at 1% strain for HDPE blown film of this density class typically exceeds 600 MPa. Elmendorf tear strength per ASTM D1922 is anisotropic in HDPE film. Machine-direction tear values are typically below 200 mN. Transverse-direction tear values exceed 800 mN. Dart impact strength per ASTM D1709 Method A for 18 µm film is above 60 g. The high modulus permits downgauging from 20 µm to 14 µm without collapse of bag opening. The bubble is collapsed through a wooden or aluminum collapsing frame. The film is gusseted on the winder. In-line punching forms the handle cut-outs. The finished T-shirt bag has a width between 300 mm and 600 mm. The film contains slip agent and antiblock masterbatch at a combined loading of 1 wt% to 3 wt%. Coefficient of friction per ASTM D1894 is maintained below 0.4. The resin is received in pellet form and is not hygroscopic. Pre-drying is not required when stored below 60% relative humidity. Published data for this specific configuration is limited. The ranges cited are typical for HDPE blown film grades of equivalent density and melt flow rate.

What limits dart impact in thin-gauge waste sack extrusion?

Waste bin liner production on the same blown film line introduces a different failure mode. The film gauge is increased to 15 µm to 25 µm. Dart impact resistance per ASTM D1709 Method B becomes the controlling specification. Typical HDPE blown film values fall between 80 g and 150 g at 20 µm. Environmental stress cracking resistance per ASTM D1693 condition B in 10% Igepal CO-630 is used to qualify the resin for long-term wet waste contact. The F50 value for HDPE film grades of this density class exceeds 50 hours. The film is coextruded in three layers. The core layer may contain post-consumer recycled polyethylene at 20 wt% to 40 wt%. Outer skins are virgin FC 82 to maintain tear and seal strength. Carbon black masterbatch is dosed at 2 wt% to 3 wt%. Carbon black particle size is specified between 20 nm and 50 nm. Dispersion quality is checked by film surface microscopy. Agglomerates above 50 µm cause pinholes. The bubble is run with a blow-up ratio of 2.5:1 to 3.5:1. A lower blow-up ratio increases MD tear. It also increases dart impact. The frost line is lowered to 4 to 6 die diameters. This reduces crystalline orientation. The finished sack is star-sealed at the bottom. Capacity ranges from 60 L to 120 L. The sack is tested for leak resistance per EN 13592. This standard specifies a 10 L water fill test without leakage for 2 minutes.

Food contact status under FDA 21 CFR 177.1520(c) 2.1.

Direct food contact film produced from Versalis HDPE FC 82 requires confirmation of the additive package against the applicable regulatory lists. The base olefin polymer is covered under FDA 21 CFR 177.1520 paragraph (c) item 2.1. This listing permits use in contact with all food types under conditions of use E through G. Condition of use E refers to room temperature filled and stored. Condition of use G covers frozen storage. The European Union framework requires compliance with Regulation (EU) No 10/2011. Overall migration limit is 10 mg/dm² of surface area. Specific migration limits for additive monomers are listed in Annex I. Verification is performed per EN 1186-1. The film is used as a monolayer bread bag liner. Gauge is 15 µm to 30 µm. Addition of food-approved slip agents is limited to 500 ppm. Antiblocking agents are dosed between 1000 ppm and 2000 ppm. Both additives must appear in the Union List of authorised substances. Printing on the film surface requires low-migration inks. Inline corona treatment raises surface energy above 38 dynes/cm per ASTM D2578. The treated film is immediately printed. The end product is a dry cereal liner. The liner is inserted into a paperboard carton. Seal strength is measured per ASTM F88. Hot-tack performance is not critical for this application.

Standard or Regulation	Designation / Clause	Application to FC 82 Film
FDA 21 CFR 177.1520(c) 2.1	Olefin polymers, food contact	Direct food contact for dry and aqueous foods
EU Regulation (EU) No 10/2011	Overall migration limit 10 mg/dm²	EU food contact compliance
REACH SVHC	Candidate List threshold 0.1% w/w	Article notification
RoHS 2011/65/EU Annex II	Pb 1000 ppm, Hg 1000 ppm, Cd 100 ppm, Cr(VI) 1000 ppm, PBB 1000 ppm, PBDE 1000 ppm	EEE component restrictions
ASTM D4976-12a	PE plastics molding and extrusion materials	Material specification
ISO 1133-1:2022	MFR at 190°C/2.16 kg	Melt flow control
ISO 1183-1:2019	Density	Density control

Five-layer coextrusion barrier film for dry food and pharmaceutical packaging uses FC 82 as the structural skin layer. The layer distribution is 40 wt% HDPE skin / 5 wt% tie / 10 wt% EVOH / 5 wt% tie / 40 wt% HDPE skin. The tie resin is a maleic anhydride grafted LLDPE with a grafting level between 0.2 wt% and 0.5 wt%. The EVOH core is a 38 mol% ethylene grade. The die is a five-layer spiral mandrel die. Each extruder runs at a set point offset. HDPE skins are extruded at 200°C to 220°C. The EVOH core is extruded at 190°C to 200°C. The tie layers are extruded at 200°C to 210°C. Melt temperature differences between layers are held below 10°C to prevent interfacial shear instability. The bubble is run at a blow-up ratio of 2.5:1 to 3:1. The frost line is set at 8 to 10 die diameters. Film gauge is 30 µm to 60 µm. Oxygen transmission rate per ASTM D3985 is below 1 cm³/(m²·day·atm) at 23°C and 0% RH. Water vapour transmission rate per ASTM F1249 is below 5 g/(m²·day) at 23°C and 85% RH. The end product is a stand-up pouch for oxygen-sensitive dry powder. The pouch is sealed on a vertical form-fill-seal line. Seal strength per ASTM F88 exceeds 15 N/25 mm. The structure is not suitable for retort or hot-fill above 80°C.

When FC 82 replaces a conventional LDPE core in heavy-duty industrial liner film

Heavy-duty industrial liner film is extruded on large blown film lines with die diameters between 400 mm and 600 mm. The film gauge is 80 µm to 150 µm. Conventional LDPE liners at 150 µm are downgauged to 100 µm when HDPE is substituted. The stiffness gain comes from the higher secant modulus. Puncture resistance per ASTM D5748 is the primary mechanical specification. Typical values for 100 µm HDPE blown film exceed 25 N. Tensile energy to break per ASTM D882 is measured in both MD and TD. HDPE film shows lower tensile energy to break than LDPE at equal gauge. This is a known limitation. The film is less forgiving at fold lines. Crease stress whitening occurs at sharp folds. The end user must accept a stiffer, less elastic sack. The advantage is higher stacking strength and lower material consumption. The liner is used as a drum liner for chemical powders. It is also used as a rubble sack on construction sites. Carbon black masterbatch is added at 2 wt% for UV resistance. The bubble is run with a low blow-up ratio of 2:1 to 2.5:1. A low BUR biases orientation toward the machine direction. This increases MD tensile strength. The extruder output is limited by bubble cooling capacity. Internal bubble cooling is used to raise output by 20% to 30%. The film is wound on jumbo rolls. Slitting is performed offline.Adhesive lamination of HDPE blown film as a base substrate for flexible packaging is performed on solventless lamination lines. The HDPE film is first corona treated. The surface energy must exceed 38 dynes/cm per ASTM D2578. The treatment must be performed in-line within 24 hours of lamination. Surface energy decays with time. A solventless polyurethane adhesive is applied at 1.5 g/m² to 2.0 g/m². The adhesive is cured at 40°C for 24 hours. The secondary substrate is aluminium foil or polyester film. The HDPE film provides moisture barrier and heat sealability. Seal initiation temperature per ASTM F1921 is between 120°C and 130°C. Final seal strength per ASTM F88 exceeds 10 N/25 mm. The laminate is used as an outer layer for stand-up pouches. The HDPE surface is printed by flexographic or gravure process. Adhesion between the HDPE film and the adhesive must exceed 2 N/15 mm per ASTM F904. Delamination at the HDPE/adhesive interface is a known failure mode. Corona re-treatment is not recommended. The film is laminated within 12 hours of extrusion to preserve surface energy. The end product is a pet food bag. The structure is HDPE 30 µm / adhesive / PET 12 µm / adhesive / HDPE 30 µm. The lamination machine runs at 150 m/min to 250 m/min. Tension control is critical. The HDPE film modulus is higher than LDPE. This reduces stretch during lamination. Registration accuracy is improved.