Polylactic Acid REVODE213TR

In cold-fill transparent food packaging, REVODE213TR is processed on standard three-zone general-purpose screws with compression ratios between 2.5:1 and 3.0:1 and check-ring non-return valves. Drying in a desiccant-bed dryer at 80 °C for 4–6 h to a residual moisture content below 250 ppm is mandatory; hopper dew point must remain below -40 °C because PLA hydrolyzes at melt temperatures above 185 °C when moisture exceeds 0.025 wt%. Melt temperature is held at 195–205 °C at the nozzle, and mould temperature is set between 20 °C and 35 °C to limit haze. Food-contact compliance is established under Regulation (EU) No 10/2011 Annex I for the lactic acid monomer (FCM substance number 134) and under the supplier’s FDA Food Contact Notification where applicable; converters must verify overall migration below 10 mg/dm² under EN 1186-1:2002 and, where required, specific migration of lactic acid using appropriate migration test methods. A typical formulation for transparent lids and clamshells adds 0.5–1.5 wt% of a PLA-compatible slip/antiblock masterbatch and 0.2–0.5 wt% of a sorbitol-free nucleating agent to reduce cycle time, at the cost of a 2–5 % increase in haze measured by ASTM D1003-21. The process involves high-speed injection with fill times of 0.2–0.5 s for wall sections of 0.6–1.2 mm, followed by hold pressures of 50–70 MPa to minimise sink marks. Terminal products include cold-fill deli cups, salad bowls, produce punnets, clear lids for dairy drinks, and hinged clamshells for bakery items; all are limited to service temperatures below 55 °C unless post-mould annealing at 90–110 °C for 20–30 min has been qualified.

When a Living Hinge in Transparent PLA Must Survive 1,000 Flex Cycles

The living hinge is the first failure zone in PLA packaging because the polymer’s elongation at break, measured on dry type I specimens under ASTM D638-14, is typically below 5 %. In closures and flip-top caps, REVODE213TR is modified with an aliphatic polyester impact modifier at 5–10 wt%, plus 0.2–0.5 wt% of an epoxy-functional chain extender to rebuild melt strength after regrind addition. The modifier increases notched impact strength from 2–3 kJ/m² to 8–15 kJ/m² when tested under ISO 179-1:2023, but it reduces light transmission from approximately 90 % to 70–80 % at 550 nm. Moulding requires a cold runner system or thermally gated hot runner with small gate diameter of 0.6–1.0 mm; the hinge zone is gated so that flow crosses the hinge transversely to prevent molecular orientation along the flex line. Screw speed is limited to 60–120 rpm, and back pressure is kept at 0.5–1.5 MPa to avoid viscous heating and yellowing. Compliance for cosmetics and personal-care closures follows REACH, EU 10/2011 if food contact is involved, and ISO 9001:2015 traceability; heavy-metal migration for cosmetics packaging is tested under EN 71-3 when formats reach toy-like dimensions. Terminal products include flip-top caps for shampoos, clear closure shells for colour cosmetic jars, translucent pill organizers, and dispensing caps for lotion bottles; published data for hinge cycle life of REVODE213TR specifically below −20 °C is limited.

What Limits Regrind Ratios in High-Clarity Lids?

Regrind use is constrained by the molecular-weight loss that occurs during each heat history. Melt-flow-rate measurements under ISO 1133-1:2022 at 210 °C/2.16 kg show an increase of 2–5 g/10 min after three passes when drying is incomplete, which corresponds to a 10–20 % reduction in weight-average molecular weight. For transparent lids, first-pass regrind from cold-runner scrap is incorporated at 10–20 wt%, while hot-runner edge trim and start-up purge are limited to 5 wt%. Above 20 wt%, notch sensitivity under ASTM D256-10 becomes the controlling variable, not haze. The processing window narrows: melt temperature must be reduced from 200 °C to 190 °C, and residence time must be held below 3 min to avoid lactide reformation and off-odour in the finished lid. Sorting and drying of regrind at 60 °C for 2 h before blending is required, because any moisture in the recycled fraction causes uneven melt viscosity and flow lines. For food-contact lids, the use of post-industrial scrap is covered under the converter’s good manufacturing practice system and the overall migration limit of 10 mg/dm² under Regulation (EU) No 10/2011; if recycled content from post-consumer sources is introduced, compliance with Regulation (EU) 2022/1616 on recycled plastic food-contact materials must be evaluated. Terminal products include high-clarity lids for cold-beverage cups, sauce portion cups, and dairy single-serve containers; haze remains below 5 % at 1 mm thickness only when regrind is kept below 15 wt% and dried to below 100 ppm moisture.

Table 1. Regrind addition limits and failure thresholds for high-clarity lid production.

Injection Moulding Parameters at the Edge of PLA’s Shear-Thinning Plateau

PLA has a sharper shear-thinning response than PET and a lower processing plateau. At the nozzle, shear rates in thin-wall moulding exceed 10,000 s⁻¹, where REVODE213TR’s apparent viscosity can drop by 60–70 % relative to its zero-shear value. Capillary rheometry data at 200 °C show a transition from Newtonian to power-law behaviour between 100 s⁻¹ and 1,000 s⁻¹; above 5,000 s⁻¹, melt fracture and gate blush appear when melt temperature is below 190 °C. Injection machines used for deep-draw clear housewares typically have screw diameter of 22–32 mm, a shot weight utilisation of 50–80 % of barrel capacity, and clamp force between 800 kN and 3,500 kN. The process uses a first-stage injection speed of 80–150 mm/s, a second-stage hold pressure of 40–65 MPa for 2–4 s, and cooling time of 8–20 s depending on wall thickness. A critical boundary occurs at wall thickness below 1.0 mm: the cooling rate exceeds PLA’s crystallisation half-time, so the part remains amorphous and exhibits high haze if mould temperature is above 40 °C. At wall thickness above 3.0 mm, sink marks and vacuum voids require gas counterpressure of 0.5–1.0 MPa or sequential valve-gate opening. Transparent housewares are compounded with 0.2–0.8 wt% of a nucleating masterbatch only when the design can tolerate a transmission drop of 5–10 %; for maximum clarity, no nucleating agent is used and mould temperature is kept at 15–25 °C. Compliance follows RoHS 2011/65/EU, REACH Article 33 SVHC screening, and mechanical testing under ISO 527-1:2019 for tensile and ISO 178:2019 for flexural properties. Terminal products include clear desk organisers, drawer storage trays, magazine files, and display stands for small retail items; these products are not intended for dishwasher service above 55 °C or prolonged UV exposure unless stabilised.

Across short-run cosmetic packaging campaigns, REVODE213TR is processed in eight-cavity hot-runner tools with pneumatically actuated valve gates to minimise gate vestige on transparent outer surfaces. The formulation is adjusted after measurement of yellowness index under ASTM D1925-70 and haze under ASTM D1003-21: a 0.1–0.3 wt% loading of a PLA-compatible UV absorber and 0.3–0.8 wt% of a scratch-resistant masterbatch are used for jars that will undergo automated filling lines. Pearlescent or tinted batches replace the masterbatch with 1–3 wt% of pigment masterbatch; the proportion is verified because loadings above 3 wt% cause brittleness and gate-stringing. The downstream process requires low-speed injection at 30–60 mm/s for thick-wall jars of 2–5 mm wall thickness, followed by extended hold pressure of 60–80 MPa for 5–10 s to prevent internal shrinkage. Mould temperature is cycled from 15–25 °C for optical clarity to 90–100 °C for stress-relief annealing of threads and snap-fit undercuts, but the two-stage thermal cycle extends total cycle time by 10–20 s. Regulatory compliance includes Regulation (EC) No 1223/2009 for cosmetic packaging safety, REACH Annex XVII restrictions, and ISO 22715:2006 for cosmetic packaging classification; if the jar contains food-like products, EU 10/2011 migration testing is added. Terminal products include transparent cream jars, compact powder bases, lip balm tubes, serum bottle over-caps, and fragrance collar inserts. Published data for long-term fragrance compatibility with unmodified PLA is limited; barrier-coated liners are recommended for aggressive solvents and ethanol-containing formulations.

Transparent Filament Feedstock for Material-Extrusion Additive Manufacturing

For filament extrusion, REVODE213TR is dried to 100–250 ppm moisture using a desiccant hopper at 70–80 °C, then processed on a single-screw extruder with a screw diameter of 25–45 mm, an L/D ratio of 28:1 to 36:1, and a melt pump for constant throughput. The formulation normally remains unfilled; where colour is required, 0.5–1.5 wt% of colour masterbatch is added at the throat, and 0.1–0.2 wt% of a heat stabilizer is used to preserve molecular weight during multiple heat histories. Melt temperature at the die is held at 180–195 °C, water-bath temperature at 40–55 °C, and filament diameter is controlled to 1.75 ± 0.05 mm or 2.85 ± 0.05 mm using dual-axis laser gauges. Ovality above 0.03 mm or diameter drift exceeding 0.05 mm leads to extruder skipping, which is the main field failure. Compliance for toys and educational filament includes EN 71-3 migration of elements, REACH, and RoHS 2011/65/EU; for food-contact printed articles, the finished printed object must be assessed under EU 10/2011 if intended for repeated contact. Terminal products are PLA filament spools for fused deposition modelling machines, used in transparent prototypes, anatomical models, jigs, and classroom printing; the amorphous printed parts have heat deflection below 55 °C under ISO 75-2:2013 method B unless annealed at 80–100 °C for 30–60 min.