When the 1002 sheet extrusion grade is directed into chilled ready-meal tray and lidstock conversion, the line is configured as follows: the resin and any reclaimed edge trim are dried in a desiccant dryer with a dew point of -40 °C at 70 °C for 4 h, producing residual moisture below 250 ppm before the material enters the extruder throat. Melt is processed in a 30:1 L/D single-screw extruder with a barrier screw, barrel zones of 180 °C, 195 °C, and 200 °C, and melt temperature maintained between 190 °C and 205 °C. Screen changer pressure is typically 90–140 bar; the melt passes a coat-hanger sheet die with lip gap 0.8–1.2 mm and is polished on a three-roll calendering stack at 25–40 °C. Final sheet gauge is 400–800 µm, with draw ratio held between 1.9 and 2.2 to limit orientation and maintain consistent plug forming. Edge trim is ground through a low-shear granulator and reintroduced at 20–30 wt% after drying; above 30 wt%, melt flow index increases by 0.5–1.0 g/10 min and sheet sag becomes measurable on the roll stack. Thermoforming uses heated syntactic foam plug assist with plug temperature 90–110 °C, sheet surface temperature 90–110 °C, mold temperature 30–50 °C, forming air 6–8 bar, and cycle time 2.5–4.0 s. Terminal products include lidded trays for chilled ready meals, cold dairy desserts, and prepared fruit portions. Food-contact compliance under EU Regulation (EU) No 10/2011 requires overall migration below 10 mg/dm² using EN 1186-1; industrial compostability is evaluated to EN 13432, with disintegration below 10% residue on a 2 mm sieve after 12 weeks and biodegradation at or above 90% within 180 days under controlled aerobic composting. Published data for this specific 1002 configuration is limited, but these processing windows are representative of PLA-based sheet grades in the same MFI range.

What Restricts the Plug-Assisted Cup Forming Window When Regrind Loading Passes 30 wt%?

High-speed cold drink cup and portion cup lines impose a narrower thermoforming window than shallow tray lines. The PLA matrix exhibits a glass transition temperature of 55–60 °C by ISO 11357-2:2020, and the sheet is formed in its amorphous state to preserve clarity; crystallization half-time at 110 °C is sufficiently long that the sheet surface must not remain at that temperature for more than a few seconds. Virgin 1002 sheet at 300–600 µm gauge is formed with a sheet surface temperature of 85–105 °C; below 85 °C, stress whitening appears at the cup base radius and sidewall microcracks develop during rim curling. Above 105 °C, web formation and sidewall thinning become non-correctable because melt strength falls sharply. The plug, machined from syntactic foam or low-thermal-mass HDPE, is held at 80–100 °C; the female aluminum mold is controlled at 30–50 °C with 5–8 bar pre-blow and final blow air. Melt flow index is measured by ISO 1133-1:2022 at 210 °C/2.16 kg and is 2–6 g/10 min for virgin feedstock. Each 10 wt% increment of edge trim regrind raises MFI by 0.2–0.5 g/10 min and reduces sag resistance; at 30 wt% regrind, sidewall thickness distribution across a 6-point profile degrades from ±8% to ±14%. The relationship is shown below.

Above 30 wt% regrind, the process window narrows to ≤20 °C, and rim curl consistency falls because melt strength decreases. Ribbed sidewalls or embossed bases increase local draw and expose instabilities. Terminal products include 200 mL–500 mL cold dessert cups, portion cups, and cold drink tumblers for fill temperatures below 40 °C. Splash filling above 40 °C is outside the amorphous PLA service limit because the article softens near the glass transition. Compliance is governed by EN 13432 for compostability and EU Regulation 10/2011 for food contact; converters are advised to verify specific migration of lactic acid using EN 1186-14 and simulant B for aqueous foods. The 0 °C cold-chain lid fit should be validated on-line, because PLA dimensional change after 24 h at 4 °C can reduce lid snap retention by 2–5% when the lid is directly thermoformed from the same sheet.

For dry-goods clamshells with an integrally hinged closure, the 1002 sheet is extruded at 250–500 µm and converted on in-line thermoformers with infrared ceramic heating. Impact modification is pre-compounded at 5–15 wt% PBAT or an equivalent compostable polyester to maintain hinge fold endurance; the hinge is then scored and folded 180° for not fewer than 50 cycles at 23 °C and 50% RH. The sheet is trimmed by matched-metal cutting in the same indexing cycle, with punch-and-die clearance below 0.05 mm to avoid delamination at the hinge. Haze is measured by ASTM D1003-13 and remains below 8% on 300 µm sheet, while Gardner impact by ASTM D5420-21 exceeds 1.5 J at 23 °C. Terminal products include transparent cosmetic accessory clamshells, toy packaging, and dry electronics accessory trays. For non-food cosmetic and retail packaging, the finished article is subject to REACH Regulation (EC) No 1907/2006 for Substances of Very High Concern screening and EU Directive 94/62/EC on packaging and packaging waste; industrial compostability is verified to EN 13432. Regrind limits for transparent clamshells are lower than for opaque tray stock, typically 10–20 wt%, because above 20 wt% yellowness index by ASTM E313-20 can exceed 4 under repeated heat history from the regrind loop.

Horticultural propagation trays and plant transport carriers sit at the boundary between industrial composting and soil fragmentation claims.

The 1002 sheet is processed into propagation trays, soil-block trays, and plant transport carriers at 350–700 µm gauge using flat-bed roll-fed thermoformers. Black or green trays are produced with 1–3 wt% compostable color masterbatch; each colorant must independently satisfy EN 13432 heavy metal limits and aerobic degradation, because the finished article is evaluated as a whole and not by base resin only. Regrind loads of 20–40 wt% are common in horticultural products because surface aesthetics are secondary; however, above 40 wt%, brittleness temperature measured by ASTM D1790-14 rises toward 5 °C, and propagation tray corner cracking increases during automated filling, stacking, and transport. The terminal products—cell trays, propagation flats, soil-block trays, and plant transport carriers—are not intended for direct soil burial. PLA blends that meet EN 13432 are industrially compostable, but the same article does not automatically meet ISO 17088 or EN 17033 for soil biodegradable mulch claims, and home compost certification is subject to a separate TÜV Austria OK compost Home or equivalent scheme. The relevant compliance matrix is shown below.

Because the sheet can be pressure formed into shallow cavities at 350–500 µm, low-moisture pharmaceutical blister trays and non-sterile medical device clamshells are converted on contact plate machines under controlled dust conditions. The sheet surface is brought to 85–100 °C by contact heating for 4–8 s; cavity depth is limited to 10–15 mm to avoid corner thinning below 60% of nominal sheet gauge. Regrind is excluded from patient-contact packaging unless a 0–10 wt% closed-loop stream is validated free of ink, adhesive, silicone, and cross-contamination. Terminal products include low-moisture nutraceutical blister trays, vial locators, and non-sterile device clamshells. Packaging validation under ISO 11607-1:2019 covers seal strength, integrity, and material compatibility; biological assessment follows ISO 10993-5:2009 and ISO 10993-10:2021 when the material is designated as a medical device packaging component. Moisture barrier is not equivalent to Aclar or PCTFE; published data for this specific PLA blend configuration is limited, so converters should measure moisture vapour transmission rate by ASTM F1249-20 before switching high-sensitivity drug formulations.

When Edge Trim Reclaim Exceeds 30 wt%, Closed-Loop Gravimetric Feeding Is Required for Uniform Gauge

Closed-loop edge trim reclamation begins at the calendering stack, where slitting removes 10–15% of sheet width. The trim is fed through a low-shear granulator with 4–6 mm screen, passed over a magnetic separator, and dried to 250 ppm residual moisture before gravimetric feeding into the extruder throat. In-line reclaim at 20–35 wt% operates on a 25:1 L/D co-rotating twin-screw extruder with side feed; however, above 30 wt%, melt temperature heterogeneity between virgin and regrind fractions is documented by infrared barrel monitoring to exceed 3 °C, increasing gauge variation along the web. Sheet gauge variation measured by beta gauge after the roll stack should remain within ±5%; above 30 wt% regrind, variation shifts to ±7–9% unless the gravimetric system controls each component within 0.5% feed accuracy. Terminal applications are short-run specialty lids, display trays, and non-food insert trays. Industrial compostability is retained only when the reclaimed material has not been contaminated with pressure-sensitive adhesive labels or crosslinked polymers; quality control should include FTIR spectra screening according to ASTM E1252-98(2021) and melt flow testing by ISO 1133-1:2022. The 1002 grade, when run with this reclaim setup, should not be diverted to food-contact sheet unless the converter verifies that all reclaimed material originates from the same food-contact-grade production and is subject to the same EU Regulation 10/2011 compliance records.