INZEA F16C Blown Film Paper Coating Compostable Polylactic Acid is a polylactic acid-based compound supplied in pellet form for melt processing on blown film and extrusion coating lines. The product is positioned for fibre-based substrates where the finished structure is required to carry industrial composting potential and renewable carbon content. In this document, “paper coating” refers to extrusion coating or extrusion lamination of a molten PLA-based web onto paper or paperboard, not to an aqueous dispersion coating. The model designation F16C identifies a grade engineered for blown film and paper coating rather than for injection moulding or thermoforming. Specifications are lot-specific and are provided in the manufacturer’s certificate of analysis; class-level data reproduced below are drawn from published processing guides for PLA-based blown film and extrusion coating compounds when manufacturer-specific data are not reproduced. Incoming lots should be verified against ISO 1133-1:2022 for melt flow rate, ISO 1183-1:2019 for density, and ISO 15512:2019 for moisture content before drying.

What distinguishes INZEA F16C from standard PLA injection-moulding and cast-film grades?

The principal difference is rheological design. Standard PLA grades for injection moulding are optimized for low melt pressure and rapid cavity filling, whereas a blown film or paper coating grade must generate sufficient melt tenacity to stabilize a bubble or a molten curtain across an air gap. INZEA F16C is therefore expected to exhibit a lower melt flow range and higher apparent melt strength at low extension rates than commodity PLA injection grades. Compared with unmodified PLA cast-film grades, F16C is formulated around film-forming and substrate wetting, with a narrower practical melt-temperature window and greater sensitivity to residual moisture. These characteristics influence bubble stability at blow-up ratios between 2:1 and 3:1 on conventional LDPE blown-film towers. The product is not a drop-in replacement for low-density polyethylene. Paper coatings based on F16C may provide stiffness and grease resistance but less puncture elongation than PBAT-modified compostable films. The table below provides class-level starting values for initial process setup and should not be used for batch release.

Target structures include extrusion-coated paper cups, food-service wrappers, folding carton liners, and blown film for compostable packaging. The selection of F16C over a standard PLA cast-film grade is driven by the need to maintain a stable melt curtain at low coat weights and to wet fibre surfaces without pinholing. In blown film mode, coextrusion with a sealant layer of a softer compostable polymer is sometimes required to improve heat-seal strength, because a PLA-rich skin can have a narrow sealing temperature range. For paper cup coating, coat weights between 15 g/m² and 30 g/m² are common targets, controlled by extruder output, line speed, and die gap. Published data for the specific INZEA F16C configuration is limited; these ranges are starting points from comparable PLA extrusion coating lines and must be revalidated on the target substrate.

Drying is the first critical operation. PLA-based compounds hydrolyze in the melt when moisture exceeds approximately 250 ppm, leading to molecular weight loss, reduced melt strength, and die-lip deposits. In production-scale desiccant drying, an inlet air dew point of -30 °C or lower, a hopper temperature of 70–80 °C, and a residence time of 4–6 h are typical for PLA film extrusion. The dried pellets should be conveyed under closed-loop dry air to the extruder throat. Processing on a single-screw extruder with a barrier screw and L/D ratio between 25:1 and 33:1 is common. Barrel set-point profiles generally begin at 160–170 °C in the feed zone and rise to 190–205 °C in the metering zone, while the screen changer and die are held at 190–210 °C. Melt temperature measured at the die lip should not exceed 210 °C for extended runs because thermal degradation can form lactide and reduce adhesion. Output rate must be balanced with screw speed and melt pressure; a short residence time of less than 30 min and a melt pressure below 250 bar are common upper boundaries for PLA extrusion coating lines. Actual limits depend on extruder size, screw design, and downstream web handling.

Compliance and Certification Matrix for Industrial Composting and Food-Contact Paper Coatings

A compostability certificate issued by TÜV Austria, DIN CERTCO, or BPI is not carried by the resin alone; it applies to the finished coated article and may be invalidated by coatings, adhesives, or inks. Published data for the specific INZEA F16C configuration may be limited, and the converter is responsible for obtaining the final article certificate. Food-contact declarations for paper coatings are evaluated under the finished article’s total migration limits, not the resin’s intrinsic composition, because low-molecular-weight degradation products can migrate into food simulants.

Adhesion loss at the paper–coating interface occurs when melt temperature, chill-roll contact, and corona pre-treatment are independently optimized but not integrated

Extrusion coating adhesion to paper is primarily mechanical interlocking into surface voids and fibre fibrils, with a secondary contribution from polar interactions between oxidized paper cellulose and the ester groups in PLA. Adhesion testing on coated paperboard commonly follows TAPPI T 569 for internal bond strength or ASTM D903 for peel strength. The target value depends on converting operations, but peel strengths below 2.0 N/15 mm may lead to delamination during die-cutting or folding. Corona pre-treatment of the paper or paperboard at 2–4 kW discharge power and line speeds of 50–150 m/min raises surface energy, but overtreatment can produce low-molecular-weight degradation products that form a weak boundary layer. The molten web must remain above its glass transition long enough for penetration; a chill roll temperature of 15–25 °C and an air gap of 100–250 mm are starting points. If the polymer chills too fast, fibre anchoring is shallow and peel adhesion drops. The practical failure mode observed on production lines is a brittle peel interface that fails below expected values after moisture exposure because water attacks the cellulose–PLA bond.

When line speed surpasses the melt’s critical shear rate in the die-lip region

Melt fracture and draw resonance are process limits. PLA has a lower critical shear rate for onset of sharkskin than many polyolefins, and this threshold decreases as melt temperature increases above 205 °C. Apparent shear rates in flat dies are calculated from die gap and throughput; for PLA extrusion coating, onset of surface roughness may occur near 10,000 s⁻¹ depending on molecular weight and additive package. The use of a coat-hanger die with a final lip gap of 0.8–1.2 mm and accurately adjusted lip bolts is required. Edge bead formation and melt curtain neck-in are further limitations; PLA coatings typically exhibit higher neck-in than LDPE at the same air gap, so line speed adjustments and die width must compensate. Bubble stability in blown film mode is governed by strain hardening and cooling rate; excessive blow-up ratio or frost-line height leads to thickness variation and film blocking. A frost-line height between 2 and 4 die diameters is a common practical range for PLA blown film, but published data for this specific configuration is limited.

Operational boundaries include moisture, temperature, and shutdown procedures. The material must not be left in a hot barrel after the line stops; a purge with a viscous PLA-compatible purge compound or unreinforced PLA grade at the same temperature prevents carbonized deposits in screw roots and die manifolds. At relative humidity above 60%, open hoppers can re-wet dried pellets within 20–30 min; therefore, hopper dryers or closed transfer systems are required. PLA melt is incompatible with polyvinyl chloride, polyethylene terephthalate, and acetal residues; contamination with even small amounts can generate acids or gels. Metal-detectable film or coating layers are outside the standard formulation design and require a separate risk assessment. The upper service temperature of the coated paper is limited by the glass transition of PLA; sustained exposure above 55–60 °C may soften the coating enough to block or deform stacked cups. These boundaries are the main operational constraints reported in field data for PLA-based paper coating lines.