High-fluidity Profax homopolymer grades in the 25 g/10 min to 40 g/10 min melt-flow band (ISO 1133-1:2022, 230 °C/2.16 kg) are processed on single-screw extruders with L/D 30:1 and barrier screw geometry delivering melt to spinnerets with 0.35 mm to 0.50 mm capillary diameter. Melt temperature is controlled at 225 °C to 245 °C. Quench air at 12 °C to 18 °C and 0.3 m/s to 0.8 m/s freezes filament surfaces before draw-jet attenuation at 0.4 MPa to 0.8 MPa. The resulting filaments reach 15 µm to 25 µm diameter and are deposited on a moving belt with basis weight from 10 g/m² to 50 g/m². Thermal bonding through heated calender rolls at 130 °C to 150 °C creates spunbond nonwovens for hygiene coverstock, medical barrier gown fabric, and filtration support layers.

The formulation for hygiene-grade spunbond requires additive discipline. Antioxidant package at 0.08 wt% to 0.15 wt% of a phenolic/phosphite blend and acid scavenger at 0.02 wt% to 0.06 wt% calcium stearate are melt-compounded on a 75 mm twin-screw extruder. Slip and antiblock concentrates are excluded because their migration to spinneret faces creates filament breaks at high draw speeds. Screen-changer pressure increase above 12 MPa at constant throughput indicates additive agglomeration or degraded gel accumulation.

Compliance for hygiene spunbond includes EU Regulation (EU) No 10/2011 overall migration limit 10 mg/dm², FDA 21 CFR 177.1520 for olefin polymers, and REACH Regulation (EC) No 1907/2006. Long-wear skin contact is assessed under ISO 10993-5:2009 and ISO 10993-10:2021 when the fabric is used in medical devices.

Why Oriented Polypropylene Film Core Layers Reject High-Comonomer Copolymer Grades?

Core-layer polypropylene for biaxially oriented film must retain high isotacticity. Profax homopolymer grades with MFI 2.5 g/10 min to 4.0 g/10 min (ISO 1133-1:2022, 230 °C/2.16 kg) provide controlled crystallization and orientation strain hardening. Copolymer-rich core layers reduce tensile modulus and cause uneven transverse stretching at draw ratios above 7:1. The cast sheet is extruded through a 1.8 m slot die at 240 °C to 260 °C and quenched on a chill roll held at 30 °C to 40 °C. Reheat orientation is conducted at 140 °C to 160 °C for machine-direction stretching and 155 °C to 170 °C for transverse-direction stretching in a tenter oven. Line speed typically ranges from 300 m/min to 500 m/min. The orientation window is narrow: below 135 °C, microvoids form; above 170 °C, disorientation and thickness-profile deterioration occur.

Three-layer coex structures use a homopolymer core with no slip agent. The core contains 0.06 wt% to 0.12 wt% antioxidant and 0.02 wt% to 0.05 wt% acid scavenger. Skin layers receive antiblock masterbatch at 0.5 wt% to 2.0 wt% and slip concentrate at 0.3 wt% to 1.0 wt%, targeting a coefficient of friction below 0.30 measured under ASTM D1894-14.

Food-contact BOPP qualifies under FDA 21 CFR 177.1520 and EU Regulation (EU) No 10/2011. Specific migration of erucamide and other slip migrants must remain below 10 mg/kg in appropriate food simulants. Converted structures include metallized snack wrappers, clear overwrap, and pressure-sensitive label facestock after corona treatment at 42 mN/m to 46 mN/m.

When Draw Ratios Above 1:6 Are Applied to Woven Sack Tape

Tape extrusion grades of Profax homopolymer with MFI 3.0 g/10 min to 4.5 g/10 min (ISO 1133-1:2022, 230 °C/2.16 kg) are extruded through flat dies with 0.8 mm to 1.2 mm die gap into a water quench bath at 30 °C to 40 °C. The quenched film is slit, then oriented in hot-air ovens at 110 °C to 140 °C. Draw ratio is set between 1:6 and 1:7. At draw ratios above 1:7, tape elongation at break declines below 12% (ISO 527-3:2018) and circular-loom breakage increases. Uncontrolled fibrillation appears at draw ratios near 1:8 when the molecular weight distribution is broad or when the water bath temperature varies by more than 5 °C.

The formulation for outdoor woven sacks includes hindered amine light stabilizer at 0.25 wt% to 0.50 wt%, calcium stearate at 0.05 wt% to 0.10 wt%, antioxidant at 0.08 wt% to 0.15 wt%, and pigment masterbatch at 2 wt% to 4 wt%. High pigment loadings alter quench rate and tape stiffness, requiring re-profiling of water bath and oven zones. End products include fertilizer sacks, pet-food bags, and FIBC bulk packaging.

FIBC fabrics are qualified under ISO 21898:2004 for non-dangerous goods packaging. UN dangerous-goods sacks require top-lift and cyclic drop tests as specified by the competent national authority. Food-contact woven sacks comply with FDA 21 CFR 177.1520 and EU Regulation (EU) No 10/2011 when the homopolymer and masterbatch are food-grade.

On thin-wall packaging lines with clamp force between 1000 kN and 2500 kN, Profax homopolymer injection-moulding grades in the 12 g/10 min to 35 g/10 min range (ISO 1133-1:2022, 230 °C/2.16 kg) are processed at melt temperature 220 °C to 250 °C and mould temperature 20 °C to 45 °C. The reciprocating screw uses L/D 20:1 to 24:1 and compression ratio 2.5:1 to 3.0:1. Injection speed is set at 150 mm/s to 350 mm/s, with holding pressure at 60% to 80% of peak injection pressure. For caps and closures, nucleating agent at 0.10 wt% to 0.25 wt% raises the crystallization onset temperature from 108 °C to 126 °C measured by differential scanning calorimetry under ISO 11357-3:2018. Mould shrinkage ranges from 1.2% to 1.6% in flow direction and 1.4% to 1.8% transverse direction (ISO 294-4:2018). Warpage is observed when mould surface temperature gradients exceed 5 °C across the core or when hot-runner valve-gate timing varies by more than 0.3 s.

The packaging formulation uses antioxidant at 0.06 wt% to 0.12 wt%, acid scavenger at 0.03 wt% to 0.08 wt%, nucleating agent as above, and external lubricant at 0.05 wt% to 0.10 wt%. Colour concentrate is added at 1 wt% to 2 wt%. Amine-based antistatic additives are avoided because they can cause discolouration in high-temperature thin-wall moulding. For metal-detectable closures used in food processing, X-ray-detectable masterbatch is added at 1 wt% to 3 wt%; published data for this specific configuration is limited.

Food-contact dairy cups, deli containers, and closures are evaluated under FDA 21 CFR 177.1520 and EU Regulation (EU) No 10/2011. Overall migration must remain at or below 10 mg/dm² in food simulants.

Thermoformed Sheet Regrind, Chill-Roll Temperature, and Plug-Assist Limits

Sheet extrusion for plug-assist thermoforming uses Profax homopolymer with MFI 1.0 g/10 min to 3.0 g/10 min (ISO 1133-1:2022, 230 °C/2.16 kg) at melt temperature 230 °C to 260 °C through a 900 mm to 1200 mm slot die with die land 0.2 mm to 0.8 mm. The three-roll stack is maintained at 60 °C to 90 °C. Roll temperatures below 55 °C quench the sheet surface too rapidly and induce differential shrinkage that appears as curl after trimming. Regrind addition above 30 wt% lowers extensional viscosity and creates sagging inside the plug-assist form station. Deep-draw depths above 50 mm require plug-timing accuracy of 0.1 s to avoid sidewall thinning below 45% of initial sheet thickness.

Food-grade sheet formulation includes nucleating agent at 0.05 wt% to 0.15 wt%, antioxidant at 0.06 wt% to 0.12 wt%, acid scavenger at 0.03 wt% to 0.08 wt%, and antistatic concentrate at 0.1 wt% to 0.3 wt%. Titanium dioxide masterbatch at 1 wt% to 4 wt% is used for white dairy cups. Thermoformed containers comply with FDA 21 CFR 177.1520 and EU Regulation (EU) No 10/2011. End products include drink cups, produce trays, and bakery clamshells.

Gamma-irradiation at 25 kGy to 50 kGy changes the melt-flow response and oxidative stability of polypropylene homopolymer unless radiation-stable additive packages are selected. For syringe barrels and rigid diagnostic consumables, Profax homopolymer grades in the 18 g/10 min to 25 g/10 min MFI range (ISO 1133-1:2022, 230 °C/2.16 kg) are injection moulded on electric machines with clamp force 800 kN to 1600 kN inside ISO 14644-1:2015 Class 7 cleanrooms. Melt temperature is limited to 220 °C to 245 °C, and mould temperature is held at 15 °C to 30 °C. Hot-runner valve gates minimize gate vestige height below 0.1 mm, which is critical for syringe lubrication. Gamma doses above 50 kGy produce measurable yellowing and notch sensitivity.

The medical formulation excludes slip agents and animal-derived additives. Radiation-stable antioxidant package at 0.10 wt% to 0.20 wt%, acid scavenger at 0.02 wt% to 0.05 wt%, and optional radiolytic stabilizer at 0.05 wt% to 0.15 wt% are used. No phthalate plasticizers are present. Compliance anchors include USP 661.1 and USP 661.2 for plastic packaging systems, ISO 10993-5:2009 for cytotoxicity, ISO 10993-10:2021 for irritation and skin sensitization, and FDA 21 CFR 177.1520 for food-contact drug-delivery accessories where applicable. End products include syringe barrels, pipette tips, and specimen containers.

Extrusion Coating on Woven Polypropylene Fabric Without Adhesion Promotion

In extrusion coating, the melt curtain is generated from Profax homopolymer coating grades with MFI 12 g/10 min to 25 g/10 min (ISO 1133-1:2022, 230 °C/2.16 kg) at melt temperature 260 °C to 290 °C. The slot die gap is 0.4 mm to 0.8 mm, and the air gap between die exit and laminating nip is 150 mm to 250 mm. Coating thickness is controlled from 15 µm to 30 µm. Adhesion to the fabric surface depends on corona pre-treatment at 40 mN/m to 46 mN/m measured with dyne solutions. Without corona treatment or without a preheated substrate at 60 °C to 80 °C, peel strength falls below 5 N/15 mm (ASTM F88/F88M-21) and the coating delaminates during sack filling.

The coating formulation includes antioxidant at 0.06 wt% to 0.12 wt% and acid scavenger at 0.03 wt% to 0.08 wt%. For untreated fabric or moisture-barrier service, 2 wt% to 5 wt% of maleic anhydride-grafted polypropylene tie resin is blended into the coating to promote adhesion. Extrusion-coated woven sacks for fertilizer, pet food, and industrial powders are tested under ISO 21898:2004. Food-contact grades comply with FDA 21 CFR 177.1520 and EU Regulation (EU) No 10/2011 for dry-food packaging.