The grade designated ecovio T2206 Sheet Extrusion/Thermoforming Compostable Biopolymer is a compounded aliphatic-aromatic copolyester/polylactide blend developed for mono- and coextruded rigid sheet. Manufacturer documentation identifies the primary polymer phases as poly(butylene adipate-co-terephthalate) and poly(lactic acid). The grade is supplied as cylindrical granules and is formulated for industrial composting under EN 13432:2000/AC:2005 and ASTM D6400-23. The certification framework requires that the organic carbon in the polymer be converted to CO₂ by at least 90% relative to a positive reference within 180 days, and that remaining solids disintegrate below 10% residue on a 2 mm sieve after 12 weeks in a controlled composting test. These end-of-life properties do not imply suitability for home compost, marine, or anaerobic lagoon environments.

Rigid sheet produced from ecovio T2206 is typically extruded in thicknesses from 200 µm to 1.0 mm and converted by contact-heat, vacuum, or plug-assist thermoforming into trays, cups, clamshell inserts, and produce packs. The grade is positioned between flexible film grades and high-flow injection-molding compostable compounds. The following representative ranges are drawn from manufacturer technical literature and lot certificates; they are not release limits. Lot-specific certificates of analysis should be obtained before tooling or packaging specifications are fixed.

Moisture control is the first critical limitation. The ester linkages in the copolyester and polylactide phases are moisture-sensitive at melt temperatures above 170 °C; uncontrolled moisture produces splay, edge tears, black specks, and lowered melt strength. The supplier processing guide specifies pre-drying at 60 °C for 2–4 h in a desiccant dryer with dew point -30 °C or lower and residual moisture below 0.10% by ISO 15512. At ambient relative humidity above 60%, drying is not optional. Additives containing free amines should be avoided unless their effect on ester cleavage has been evaluated, because amine-catalysed transesterification can degrade melt strength before the die.

What Screw Speed and Barrel-Temperature Profile Prevent Unmelts on a 30:1 Sheet Line?

On a 75-mm single-screw extruder with 30:1 L/D and a barrier screw, stable operation is obtained at 80–120 min⁻¹ screw speed and 50–80 bar adapter pressure. A typical reverse barrel profile from feed to metering is 150 °C/160 °C/170 °C/175 °C/180 °C, with melt temperature at the adapter held below 190 °C. Screw speeds above 120 min⁻¹ can raise melt temperature into the degradation regime; speeds below 60 min⁻¹ reduce output and extend residence time. Vacuum venting at -0.08 MPa is recommended. On lines with 28:1 L/D or lower, unmelts have been observed at nominal throughput; published data for this specific configuration is limited.

The single-point melt-volume flow rate is not sufficient to predict sheet sag. In T2206 the MVR range of 4.0–6.0 cm³/10 min at 190 °C/2.16 kg places the grade in a higher-viscosity class than injection-molding compostable compounds. Isothermal frequency sweep data from parallel-plate rheometry show shear-thinning behaviour over 0.1–100 rad/s, but quantitative complex viscosity curves are not always included in standard lot certificates. The practical consequence is that sheet sag remains manageable at 200–1000 µm thickness only if the melt temperature is held below 190 °C and the roll-stack gap is set to the target sheet thickness.

Thermal degradation in T2206 is governed by two pathways: hydrolysis of ester bonds by residual water and thermal chain scission at elevated temperatures. Near 200 °C, the melt-volume flow rate can increase by 0.5 cm³/10 min per hour of residence time, which manifests as progressive sheet sag and loss of hot melt strength. General kinetic studies of polylactide degradation report pseudo-first-order random chain scission with activation energy in the range of 170–190 kJ/mol; whether T2206 exactly follows that value is not stated in standard technical data sheets. Accordingly, the processing window should be treated as a threshold limit rather than a normal operating target.

The extruded web is quenched on a three-roll polishing stack. Roll temperatures between 30 °C and 45 °C are used to reduce blocking and limit frozen-in stresses. A small air gap below 25 mm minimizes neck-in and surface oxidation. Higher roll temperatures produce blocking and optical haze; lower temperatures increase post-trim curl. The sheet is then wound or routed directly to the thermoformer.

When the sheet enters a contact-heat thermoformer, the surface temperature must be raised to 70–85 °C for T2206. This band is narrower than amorphous PET, which has a higher glass transition. Plug-assist aluminum tools should be maintained at 30–40 °C, and mold temperatures should be 30–50 °C. If the sheet surface temperature exceeds 85 °C, the plug punctures the sheet or webbing forms between cavities. Below 70 °C, corner thinning and stress whitening increase. Draw ratios below 2:1 are preferred for unsupported cavity depths; deeper parts require multi-stage plug heating or coextruded skins. The grade is unsuitable for hot-fill applications exceeding its Vicat softening temperature of 58–65 °C because distortion occurs under load.

Tooling for T2206 differs from amorphous PET and high-impact PS. Aluminum plug temperatures of 30–40 °C reduce sticking, while female mold cavities require venting channels of 0.3–0.5 mm depth to prevent trapped air. Without mold release, residue accumulation on polished surfaces has been observed after extended runs. Mold release selection must be screened for its effect on compostability certification and food-contact migration.

Compostability Certification and Food-Contact Verification Boundaries

Compostability certification under EN 13432:2000/AC:2005 is a multi-test system, not a single property. Biodegradation is evaluated by ISO 14855-1:2012 or ISO 14855-2:2018, disintegration by ISO 16929:2021, and compost quality by ecotoxicity testing according to OECD 208. For ASTM D6400-23, the corresponding biodegradation method is ASTM D5338-15. The certification does not cover marine or home compost conditions. A separate claim for home compost may exist for specific film grades, but it should not be inferred from T2206 literature unless explicitly stated.

Food-contact status is not intrinsic to the polymer. Finished articles must be tested under EU Regulation 10/2011 with the appropriate food simulants, and United States applications must be confirmed against FDA 21 CFR 175.300 or FDA 21 CFR 176.170 depending on the finished article. Additives, regrind, printing inks, and barrier layers can alter migration behaviour, so final compliance must be verified on the thermoformed part.

When T2206 Replaces PET, PS, or Polylactic Acid Homopolymer in Rigid Packaging

Compared with amorphous PET sheet, ecovio T2206 has lower density 1.25–1.27 g/cm³ versus 1.34 g/cm³, lower tensile modulus 2200–2700 MPa versus 2800–3500 MPa, and lower Vicat softening temperature. The material therefore reduces part mass but cannot be used in hot-fill or retort applications. Oxygen and water vapour transmission through T2206 in final thermoformed articles is not equivalent to PET; published barrier data for specific geometries is limited, and barrier coatings or multilayer structures should be qualified separately.

Compared with high-impact polystyrene sheet, T2206 is denser 1.25–1.27 g/cm³ versus 1.03–1.06 g/cm³ and requires drying, but it carries industrial compostability certification. A PS thermoforming tool can often be reused, but lower sheet surface temperature 70–85 °C and different plug release characteristics require cycle-time adjustments. Compared with polylactic acid homopolymer, T2206 contains poly(butylene adipate-co-terephthalate) as a toughness modifier, which increases notched Charpy impact and reduces brittleness, but lowers modulus and introduces a polyester degradation pathway that must be controlled through moisture management.

Within the ecovio family, the T2206 designation denotes a sheet and thermoforming grade. It is not functionally interchangeable with high-flow injection-molding compostable grades or flexible film grades. Flexible film grades are compounded for high tear resistance and low stiffness; T2206 shifts the balance toward flexural modulus and dimensional stability in thin-walled rigid parts. Published data for direct comparative extrusion trials between T2206 and other ecovio grades is limited.

Regrind use at 20–30% by mass in monolayer sheet is possible if the regrind is dust-free and dried. Regrind originating from printed or coated sheet must be segregated because inks and coating binders can introduce particles larger than 2 mm after disintegration and alter compostability. Higher regrind levels elevate MVR and reduce Charpy impact. Batch-to-batch MVR variation within ±0.5 cm³/10 min has been observed on certificate-of-analysis data and can shift thermoforming heat settings by approximately 5 °C. The grade should not be processed above 200 °C, and residence time in the die should not exceed 10 min at that temperature.