Thermoformed Hot-Fill Lids: Plug-Assist Speed and Flange Warpage

Sheet conversion of Ecoplant HRS for hot-fill lid stock requires pre-drying in a desiccant dryer at 80 °C for 4 h to a residual moisture content at or below 250 ppm, measured by ISO 15512. Pellets stored in silos at ambient relative humidity above 60% are conveyed in dried air with a dew point below −40 °C; otherwise moisture regain at the feed throat accelerates hydrolysis and reduces melt strength within 20 min of exposure. The dry blend typically combines 80 wt% virgin Ecoplant HRS with 20 wt% internal regrind from thermoforming trim, provided the regrind has not exceeded two heat histories and its melt flow index remains within 10% of the virgin value under ISO 1133-1:2022 at 210 °C/2.16 kg. Sheet extrusion on a single-screw extruder with L/D 30:1 and a barrier screw is set across five zones from 170 °C to 195 °C, keeping melt temperature at 185–195 °C and melt pressure at the screen changer between 80 bar and 120 bar. The die gap is set at 0.4 mm to produce sheet of 0.80–0.90 mm, with gauge variation controlled within ±0.04 mm by a beta gauge. During plug-assist thermoforming, the sheet surface temperature is held at 95–105 °C using an IR pyrometer, plug speed is bracketed at 150–250 mm/s, and mould temperature is maintained at 105–115 °C with uniformity within ±3 °C. Flange warpage is the dominant failure mode when mould temperature gradients exceed this band; residual stress release becomes visible as out-of-plane distortion above 0.5 mm across a 100 mm flange length. Terminal products are hot-fill cup lids and insert trays with wall thickness of 0.35–0.50 mm, undercut retention tabs, and hinged fold lines designed to withstand 200 flex cycles without whitening. Food-contact compliance requires specific migration testing under EU 10/2011 using EN 1186-1 overall migration simulants; overall migration below 10 mg/dm² is required for the finished article, and any additive package used in the HRS modification must not raise migration into 3% acetic acid or 10% ethanol. US applications require the supplier’s Food Contact Notification or confirmation that the compounded formulation falls within 21 CFR 175.300 for resinous and polymeric coatings. EN 13432 industrial compostability claims are acceptable only if the final article and the conversion-induced oligomer profile pass the full test suite; residual regrind above 30% can elevate crystallinity and slow disintegration beyond the 12-week threshold.

Can Flexible PLA Retain Dimensional Stability at 85 °C in Automotive Map Pocket Backings?

Because automotive interior parts are validated against long-term heat ageing and low-speed impact, Ecoplant HRS is processed as virgin pellets without external regrind unless the converter demonstrates that 10 wt% closed-loop regrind does not shift notched Izod impact by more than 15% of the virgin value under ISO 180:2019 at 23 °C. The grade is pre-dried at 80 °C for 4 h to 200 ppm moisture, then sheet-extruded on a 30:1 L/D single-screw line with a melt temperature of 180–200 °C and formed into 0.80–1.20 mm sheet. Vacuum thermoforming on aluminium tooling maintained at 105–115 °C is preferred over high-pressure forming because the flexible HRS phase exhibits lower modulus at forming temperatures and can be drawn into map pocket radii of 2.5 mm without corner thinning beyond 35% of nominal wall. Heat deflection temperature is measured according to ISO 75-2:2013 method B at 0.45 MPa flexural stress; a target value of 100 °C or higher is required for trim panels exposed to solar soak in closed vehicles, while a typical unmodified amorphous PLA would remain below 60 °C under the same stress. Flexural modulus is tested to ISO 178 at 23 °C and is maintained between 2200 MPa and 2800 MPa so that the panel resists rattle but retains enough compliance for snap-fit assembly to door carriers. Volatile organic compound testing according to VDA 277 is initiated at the compounded-pellet stage; total VOC emissions above 100 µgC/g can trigger OEM rejection even when mechanical properties are acceptable, and any colour masterbatch is screened for low-molecular-weight amides and plasticizers before addition. Long-term heat ageing at 85 °C for 500 h in a forced-air oven following ISO 188 detects post-crystallization shrinkage; the HRS modification should limit dimensional change to 0.8% or less, although published data for this specific grade in interior trim exposure is limited and lot-to-lot verification is required. Terminal applications include non-visible door map pocket backing panels, seat back trim substrates, and HVAC deflector frames where flexible snap hooks are moulded or heat-staked. The material is not adhesively bonded with solvent-based primers containing high ketone concentrations without compatibility testing because local stress cracking may initiate at the bond line.

When Extrusion Blow Moulding Replaces Polyethylene in Small Cosmetic Bottles

On single-station shuttle blow moulders with 120 mm centre line and screw L/D 24:1, Ecoplant HRS requires a melt temperature window of 175–195 °C to maintain hanging parison stability. Melt strength is characterized by a Goettfert Rheotens unit or equivalent capillary draw test; a drawdown velocity at break above 300 mm/s at 190 °C is generally necessary to prevent sag-induced wall thinning below 0.25 mm at the shoulder of a 200 mL container. The formulation is run at 95 wt% Ecoplant HRS with 5 wt% PLA-based color or antiblock masterbatch; polymer-carrier masterbatches with olefinic carriers are avoided because they depress weld line strength in the pinch-off zone. Parison programming delivers a wall profile from 1.8 mm at the neck to 0.9 mm at the base before inflation, with blow pressure between 4 bar and 6 bar and blow time of 8–12 s. Mould temperature is held at 20–30 °C to freeze-in dimensional accuracy, and the article is demoulded at 40 °C or below to avoid post-mould creep. The pinch-off weld is the limiting mechanical zone; a minimum seal flash thickness of 1.5 mm and a land angle of 30° on the tool reduce notch sensitivity. Terminal products are 150–250 mL cosmetic bottle bodies and dry powder containers with wall thickness of 0.50–0.70 mm. REACH Regulation (EC) No 1907/2006 requires a full Article 33 SVHC screening at the formulated-pellet level, and RoHS Directive 2011/65/EU restricts heavy metal residues from colourants. Melt residence time does not exceed 8 min at 195 °C; longer residence leads to a measurable increase in melt flow index of more than 20% under ISO 1133-1:2022 and corresponds to molecular weight loss in the polyester backbone. At shutdown, the moulding machine is purged with a low-MFI acrylic or purging compound rather than polyethylene, because residual PE contamination in the recycled HRS stream creates delamination in subsequent bottle walls.

Following a 5 h desiccant drying cycle at 80 °C to a target moisture at or below 150 ppm, filament conversion of Ecoplant HRS begins on a 25 mm single-screw extrusion line with L/D 28:1 and a melt pump. Barrel zones are profiled from 180 °C to 205 °C, and the melt pump suction pressure is maintained at 20–30 bar to dampen motor speed fluctuations. Filament diameter is controlled by a dual-axis laser gauge to 1.75 mm with ovality within ±0.05 mm; water bath temperature is set at 55–65 °C to avoid voiding from overly rapid quench. Fused filament fabrication parameters are established according to ISO/ASTM 52921 with nozzle temperature 215–225 °C, bed temperature 60–80 °C, enclosed chamber temperature 40–60 °C, layer height 0.2 mm, and print speed 40–60 mm/s. Heat resistance in printed geometries is developed by post-print annealing at 90 °C for 1 h in forced air, which raises the ISO 75-2 method B deflection temperature into the 110–125 °C range for crystalline regions, although published data for this specific HRS grade under FFF annealing is limited and should be confirmed by differential scanning calorimetry to ISO 11357-3. Terminal products include vacuum fixture plates, pick-and-place nests, and jig bodies exposed to short 80 °C cycles. RoHS Directive 2011/65/EU compliance requires XRF screening of the filament for Cd at or below 100 ppm and Pb, Hg, CrVI, PBB, and PBDE at or below 1000 ppm; the grade should not be used for food-contact printed tooling unless EU 10/2011 and FDA migration tests are separately completed on the printed surface.

For cast film lines running at 18–22 m/min, a 60:40 mass ratio of Ecoplant HRS and standard PLA with an MFR of 6 g/10 min at 210 °C/2.16 kg is dry-blended to reduce modulus and increase tear resistance. The melt is extruded through a 0.5 mm die gap onto a chill roll held at 20 °C, with corona treatment to 38–42 mN/m before winding. Film thickness is maintained at 30–50 µm with gauge control within ±3 µm. Machine-direction tensile elongation at break should exceed 180% under ISO 527-3, and Elmendorf tear strength is measured by ISO 6383-2 at 5–7 N/mm for the machine direction to ensure slitting performance. Heat-seal strength of the finished lamination is tested according to ASTM F88/F88M-21 at 120–140 °C seal dwell; seal initiation temperature is typically 15–20 °C above that of unmodified PLA film, so converter sealing jaws require a wider temperature band. Terminal products are compostable lamination windows in paper pouches, label facestock, and overwrap for dry goods. EN 13432:2000 claims require whole-film biodegradation of 90% or more within 180 d, disintegration within 12 weeks, and ecotoxicity pass under Annex E; certification is required for each final film construction because the HRS modification can alter oligomer release. The film is not classified as home compostable unless a separate home compost certification covering the exact thickness is issued. Ambient storage above 60% relative humidity requires resealed moisture-barrier packaging after slitting; moisture regain above 0.5 wt% in film feedstock can produce bubble defects during lamination.

Injection Moulding Heat-Resistant PLA: Gate Freeze and Weld Line Strength

Injection moulding Ecoplant HRS in a 120-ton hydraulic machine with a 20:1 L/D barrier screw requires pre-drying at 80 °C for 4 h to at or below 200 ppm moisture and shot-size management that keeps melt residence time below 7 min at 180–200 °C. The central process conflict is mould temperature: a cold mould at 25–30 °C freezes an amorphous structure with low shrinkage but leaves the part with an ISO 75-2 method B heat deflection temperature below 60 °C, while a hot mould at 100–110 °C increases crystallinity and heat resistance but extends cycle time and increases ejection drag. For heat-resistant brackets, the stationary tool is heated to 100–110 °C and the moving tool to 80–90 °C, with cycle times of 45–60 s for a 3 mm nominal wall. Isothermal crystallization half-time at 100 °C is verified by differential scanning calorimetry to ISO 11357-3; if the half-time exceeds 3 min, the mould should be considered unacceptably slow for high-volume production. Injection pressure is set between 100 MPa and 140 MPa, holding pressure between 60 MPa and 80 MPa, and gate diameter at 1.2–1.6 mm for a 3 mm wall to delay gate freeze while preventing jetting. Mould shrinkage is measured after 24 h to ISO 294-4; transverse shrinkage generally falls within 0.6–1.0% and flow-direction shrinkage within 0.4–0.8%, but these values shift if regrind above 15 wt% widens the molecular weight distribution. Weld line strength is evaluated by flexural testing to ISO 178; retained flexural strength at the weld line should be at least 65–75% of the un-welded value, and gate placement is adjusted to move weld lines away from screw bosses and snap hooks. Terminal parts include appliance feet, steam mop tank brackets, and internal clips in coffee machines where short-term exposure to 80–100 °C is expected. Flame performance is limited to UL 94 HB unless a halogen-free flame-retardant package is externally validated; untreated Ecoplant HRS is not specified for unsupervised current-carrying parts or glow wire applications requiring compliance at 850 °C. The material must not be blended with PVC regrind or water-soluble purge residues, because hydrochloric acid release from PVC and alkaline residues from purging agents accelerate polyester hydrolysis. Drying above 85 °C is avoided because flexible modifier agglomeration at the feed throat may occur, causing screw slip and batch-to-batch melt pressure variation.