In blown film conversion for compostable waste sacks and retail carrier bags, SOLPOL-1000B is metered at 20–30 wt% with a PBAT-rich base resin through a gravimetric dosing unit and processed on a single-screw extruder with 25:1–30:1 L/D, screw diameter 45–55 mm, and spiral mandrel die gap 1.2–1.8 mm. Pre-drying at 70–80 °C for 4 h in a desiccant dryer reduces residual moisture below 250 ppm; when ambient relative humidity exceeds 60%, closed conveying and hopper dryers are required to prevent hydrolysis-induced bubble rupture at gauge below 15 µm. Melt temperature at the die is maintained between 150–165 °C, melt pressure is held at 200–320 bar by screen pack selection, and screw speed is kept at 40–80 rpm to limit shear heating. Blow-up ratio is restricted to 2.5:1–3.5:1 because higher transverse orientation creates thickness variation above ±8% and reduces machine-direction Elmendorf tear. Film gauge is set at 12–35 µm according to sack duty. Tensile strength and elongation at break are measured by ASTM D882, dart impact by ASTM D1709 method A, and tear resistance by ASTM D1922. Heat seals are produced at 120–130 °C, dwell 0.5 s, and pressure 0.3 MPa, with seal strength determined by ASTM F88. Conformity with EN 13432 requires aerobic biodegradation of at least 90% within 180 days by ISO 14855-1, disintegration above 90% after 12 weeks by ISO 16929, and ecotoxicity testing by OECD 208; ASTM D6400 applies equivalent thresholds for U.S. industrial compost acceptance. In hot and dry bubble-cooling conditions, pinhole formation at 12 µm is a recorded field failure mode unless the air ring provides chilled air at 5–10 °C with a dew point below 15 °C. End products include compostable refuse sacks, produce rolls, and retail carrier bags with printability governed by surface treatment to 38–42 mN/m dyne level.

What Processing Limits Govern Extrusion Coating onto Compostable Paperboard?

Extrusion coating of kraft paperboard with a SOLPOL-1000B-modified PLA/PBAT layer is constrained by the thermal sensitivity of the polyester phase and the need to prevent PLA block crystallization during draw-down. The coated structure is produced on a 45–60 mm single-screw extruder fitted with a barrier screw and a coathanger die; melt temperature at the die is restricted to 155–175 °C, and the die is positioned 150–250 mm above the nip to limit neck-in to 15–20 mm. The compound is first dried to below 200 ppm moisture at 70 °C for 6 h. Chill roll temperature is controlled at 15–25 °C, nip pressure at 3–5 N/mm², and paperboard moisture at below 5% to prevent steam-generated voids. Melt flow rate determined by ISO 1133-1:2022 at 190 °C/2.16 kg is adjusted to 8–15 g/10 min using the elastomer content to improve fibre wetting; however, the higher MFR window simultaneously raises coating weight variation beyond 15–25 g/m². Adhesion strength is measured by TAPPI T 540 with a target not less than 1.0 N/15 mm; bond failure at the paperboard fibre layer, not at the interface, is required. Food-contact status under EU 10/2011 requires overall migration below 10 mg/dm² and specific migration control for lactic acid, adipic acid, 1,4-butanediol, and terephthalic acid. U.S. FDA status must be confirmed against the specific food-contact notification for the formulated coating layer. Compostability of coated board is assessed by ASTM D6868 and EN 13432, referencing ASTM D5338 or ISO 14855-1 for aerobic biodegradation. End products include hot beverage cups, compostable food trays, sandwich packs, and folding carton liners.

When melt-compounded in a co-rotating twin-screw extruder with 40:1 L/D and barrel profile 160–190 °C, SOLPOL-1000B at 10–20 wt% acts as an impact modifier for PLA-rich injection-moulding compounds. The compounded pellets are dried to below 250 ppm moisture before moulding. Injection moulding uses a barrel profile of 160–180–180–175 °C rear-to-nozzle, back pressure 5–10 bar, screw rotation 60–120 rpm, and mould temperature 80–100 °C to promote PLA crystal nucleation and reduce cycle time. A 12-cavity spoon tool with shot weight of 8.5 g requires clamp force of 800–1,200 kN; gates are cut to 0.8–1.2 mm thickness and 1.5–2.5 mm width to avoid shear-induced cleavage of the elastomer phase. Residence time is held below 10 min to prevent PLA molecular weight loss beyond 5% and lactide reformation at the nozzle. Notched Charpy impact by ISO 179-1/1eA increases from 2–3 kJ/m² to 5–8 kJ/m² at 15 wt% addition, while tensile modulus by ISO 527-2 decreases from 3,200 MPa to 2,200–2,500 MPa. Annealing at 80 °C for 30 min after ejection stabilises crystallinity and reduces post-mould warpage. Moisture uptake above 0.3% in storage above 60% RH is an operational boundary because hydrolytic embrittlement in the polyester phase accelerates. Disintegration under ISO 20200 at 58 °C must exceed 90% after 90 days for many biowaste collection schemes; EN 13432 conformity for compostable cutlery requires the full biodegradation and ecotoxicity sequence, while food-contact articles must be verified under EU 10/2011 and the applicable U.S. FDA food-contact notification for the formulated grade. End products include knives, forks, spoons, coffee stirrers, and hotel amenity articles.

Seal Initiation Temperature in PBAT-Rich Pouch Sealant Layers

Sealant-layer formulation for compostable flexible pouches incorporates SOLPOL-1000B at 15–25 wt% to depress seal initiation temperature without sacrificing interlayer adhesion in coextruded films. The sealant layer is coextruded at 10–20% of total thickness, with die melt temperature 155–170 °C on a three-layer blown or cast line. Seal initiation temperature is measured by ASTM F2029 at a threshold seal strength of 4.4 N/25.4 mm; PBAT-rich sealant layers containing the elastomer typically initiate at 95–110 °C, whereas unmodified PLA-rich sealants require 120–130 °C. Hot tack is measured by ASTM F1921 at dwell 0.5 s and pressure 0.275 MPa; recorded failure modes include stringing and seal lift-off at fill speeds above 60 pouches/min. Seal strength after cooling is measured by ASTM F88 at jaw separation rate 200–300 mm/min. The complete pouch structure must meet EN 13432 or ASTM D6400 compostability thresholds: ≥90% biodegradation by ISO 14855-1 within 180 days, ≥90% disintegration by ISO 16929, and ecotoxicity per OECD 208. Food-contact compliance under EU 10/2011 requires overall migration below 10 mg/dm² and specific migration control for lactic acid, adipic acid, 1,4-butanediol, and terephthalic acid; U.S. status requires confirmation under the applicable FDA food-contact notification. End products include dry-food stand-up pouches, fresh-produce zipper bags, and side-gusset pouches for coffee and tea.

Direct extrusion of PLA-based sheet containing 10–25 wt% SOLPOL-1000B is performed on a 35–50 mm single-screw flat-die line with melt temperature 165–180 °C, die gap 0.8–1.2 mm, and calender rolls set at 40–60 °C to keep initial crystallinity below 10%. Sheet thickness is controlled between 300–800 µm. Thermoforming is conducted on a plug-assisted pressure former at sheet surface temperature 90–110 °C measured by infrared pyrometry, with aluminium tooling at 20–30 °C and forming pressure 5–7 bar; the elastomeric phase reduces strain hardening, so unmodified PLA pressure settings of 3–4 bar are insufficient. Draw ratios above 1.5:1 are not recommended because corner wall thickness falls below 150 µm and orientation-induced stress concentrates at the plug contact. Sag resistance is assessed as deflection at 100 °C; sheet with crystallinity above 15% resists sag but limits edge trim regrind compatibility to 20–30%. Food-contact verification follows EU 10/2011 and applicable FDA food-contact notifications; compostability certification of the finished tray follows EN 13432 or ASTM D6400 with ISO 14855-1 and ISO 20200 disintegration tests. End products include produce punnets, clamshells, bakery trays, and cold-serve food trays.

When Agricultural Mulch Film Must Meet EN 17033 Soil Degradation Requirements

Compostable agricultural mulch film containing SOLPOL-1000B is extruded as a 10–25 µm monolayer on monotube blown film lines with die melt temperature 150–165 °C; the finished roll is laid in widths up to 1.2 m by tractor-mounted equipment. EN 17033 governs this application and requires soil biodegradation of at least 90% within 24 months by ISO 17556 at 20–25 °C, plus ecotoxicity assessments under OECD 208 and OECD 222. Carbon black masterbatch at 2–4 wt% reduces solar transmittance and slows ester hydrolysis during the service window, but raises bulk density and reduces transparency. After 100 h of QUV exposure with UVA-340 lamps at 0.68 W/m², tensile strength retention above 50% is a common field target, although published data for this specific grade at submicron gauge is limited. Burial below 15 cm before crop harvest is an operational limitation because premature disintegration destroys weed suppression. End products include biodegradable mulch for tomato, strawberry, and vineyard applications where retrieval from soil is impractical.