Bio-Flex F 1110 is a PLA-based thermoplastic compound supplied for blown film extrusion in short-use and compostable packaging applications. The pelletized grade is a melt-compounded blend of polylactic acid and a biodegradable copolyester phase, formulated to reduce the inherent brittleness of neat PLA while retaining sufficient melt strength for bubble stability. Published flow data place the melt volume-flow rate at 190 °C under 2.16 kg piston load in the range 3–6 cm³/10 min when tested to ISO 1133-1:2022; density is reported at 1.24–1.26 g/cm³ under ISO 1183-1:2019. The material is characterized by a high renewable carbon fraction and is usually certified by the compounder for industrial compostability under EN 13432:2000; direct reliance on certification requires confirmation of the exact additive masterbatch and final film thickness used downstream.

How does the grade respond to typical LDPE blown-film machine settings?

Processing latitude is narrower than that of fossil LDPE. Pre-drying in a desiccant-air dryer at 70–80 °C for 4–6 h is required to reduce pellet moisture below 0.025 %. Residual moisture above that threshold hydrolyzes PLA during extrusion, lowering melt viscosity and producing unstable bubble geometry, die-lip plate-out, and surface sharkskin on film. On a production line with a 45 mm single-screw extruder having 30 L/D and a three-zone screw with a Maddock mixing element, the barrel profile is generally set between 150 °C and 185 °C from feed to metering, with the die held at 180–200 °C. Feed-throat cooling should remain active to prevent pellet bridging.

Bubble geometry differs from LDPE because the melt exhibits lower elongational viscosity and less strain-hardening. Die gaps of 0.8–1.2 mm, blow-up ratios between 1.8 and 2.6, and frost-line heights of 4–8 die diameters are typical starting conditions. The lower melt strength makes the bubble sensitive to high air-ring velocities and to rapid cooling; unstable boundary layers or helical instability are observed when the frost line is raised too far or the melt temperature exceeds 200 °C. Output is limited by bubble stability rather than drive load. Regrind levels above 20 % may reduce dart impact and should be qualified on the target line.

Short-use shopping bags and fruit and vegetable films are the primary application window. Film in the 20–40 µm range can be heat-sealed using impulse or constant-heat sealing; seal strength reaches useful levels when the jaw temperature is maintained at 110–130 °C and dwell time is at least 0.5 s. The seal window is narrower than LDPE and is sensitive to film orientation. Bags produced from unmodified film may tear at the seal perimeter if the seal bar pressure is excessive. Because the grade has higher stiffness than flexible copolyester-rich biodegradable compounds, it is better suited to crisp, oriented films than to stretch films or elastic packaging.

When replacing LLDPE in short-life packaging, which mechanical trade-offs require redesign?

Compared with LLDPE, Bio-Flex F 1110 typically delivers higher tensile modulus and lower puncture resistance at equal gauge. Tensile properties measured according to ISO 527-3:2018 on 30 µm mono-layer blown film tend to be in the range 25–40 MPa tensile strength and 150–250 % elongation at break; published data for the specific film configuration is limited and depends on draw-down ratio. Dart impact, measured by ISO 7765-1, is generally lower than LLDPE at the same thickness, so package design must compensate by increasing gauge or reducing stress concentration. Tear propagation resistance measured by ISO 6383-2 is directional; machine-direction tear is often lower once the film has been oriented at high take-up speed.

Haze and clarity are close to PLA but not identical to LDPE. For 25–35 µm film, light transmission measured by ASTM D1003 typically exceeds 85 %, while haze may be higher than LLDPE but acceptable for produce packaging. These values shift with frost-line height and blow-up ratio. Surface energy of freshly formed film is usually adequate for water-based flexographic inks after corona treatment to 38–42 mN/m. However, PLA surfaces age faster than polyethylene; adhesion loss occurs if treated film is stored above 30 °C or at relative humidity above 60 % for more than 48 h. The grade is sensitive to extended UV exposure and is not intended for durable outdoor films.

Regrind recovery and hydrolysis limits

Edge trim and start-up scrap can be re-processed if kept dry and free of polyethylene contamination. In production-scale converting, contamination with LDPE as low as 2–5 % can cause visible gels, delamination, and reduced transverse-direction tear because the two phases are thermodynamically incompatible. PET and PVC contamination create severe degradation: PLA hydrolyzes in the presence of PVC thermal degradation products, leading to carbonized deposits and bubble holes. The recommended regrind fraction is usually 10–20 % for printable film and 20–30 % for waste liners; higher fractions decrease puncture impact and increase gel counts. If regrind has been stored in humid conditions, it must be re-dried at 70 °C for at least 4 h.

Residence time above 200 °C should be minimized. Prolonged hold-up in the die, adapter, or screen pack promotes lactide reformation, which is observed as acidic odor, lower bubble strength, and white die-lip deposits. Frequent purging with low-MFR polyethylene before shutdown is not compatible; dedicated purging compounds for PLA-based materials are recommended.

The grade is positioned between rigid PLA and flexible copolyester-rich film compounds

Within the Bio-Flex film portfolio, F 1110 is normally differentiated by its higher PLA content, which raises tensile modulus and lowers elongation at break relative to grades designed for elastic agricultural films. Higher-flexibility biodegradable blown-film compounds may exhibit elongation at break above 400 % and lower modulus, whereas F 1110 remains in the 150–250 % elongation range. This stiffness improves bubble collapse and downstream converting at the cost of limited stretch and lower puncture resistance. The grade is therefore selected for short-use bags, lamination films, and compostable packaging requiring dimensional stability, rather than elastic cling or high-dart applications.

Compostability claims are only valid when the complete film, including pigments, inks, and adhesives, has been assessed as an article. The base resin is normally evaluated under EN 13432:2000, which requires biodegradation of at least 90 % within 180 days, disintegration residues above 2 mm below 10 % after 12 weeks, and absence of ecotoxicity. Corresponding test methods include ISO 14855-1 for aerobic biodegradation, ISO 16929 for disintegration, and OECD 208 for ecotoxicity. Under ASTM D6400, the material is intended for industrial composting facilities, not home compost or soil burial. The presence of conventional plastic contaminants above 1 % may cause failure at sorting or disintegration stages.

Storage at 20–30 °C in sealed original bags is required. Pellets exposed to ambient air above 60 % RH can reach moisture content above 0.025 % within 24 h, making immediate drying before extrusion necessary. Masterbatch loading must be kept low. Color concentrates based on PE carriers are incompatible; only PLA or biodegradable copolyester carriers should be used at 2–4 % addition. Above 5 %, masterbatch incompatibility creates gels and lowers transverse-direction tear. Slip and antiblock additives should be selected from compostable approved sources.

What limits high-speed converting of Bio-Flex F 1110 on bagmaking lines?

High-speed bagmaking imposes different constraints from film blowing. The material has a lower coefficient of friction than LDPE, which can cause slippage on roller nip systems; corona treatment and antistatic masterbatches may be required. Sealing temperature sensitivity is higher than LDPE; the difference between acceptable seal strength and burn-through or film shrinkage is often 5–10 °C. Because the film begins to shrink near the seal bar at 120–130 °C, jaw temperature must be profiled and dwell time minimized. Rotary sealing lines achieve better results than flat-bar sealers because the film web is not stationary over the heated element. These limitations define the practical speed ceiling and require line-specific optimization.

Field data from film producers indicate that edge trim recovery is most successful when the trim is granulated immediately after extrusion rather than stored as loose film. Loose film absorbs ambient moisture and creates feeding irregularities. Dedicated granulator knives should be maintained to avoid fines above 3 %, because fines can cause screw slippage and melt-temperature variation. On high-output lines, an automated edge-trim feedback system with gravimetric dosing of regrind at 12–18 % is commonly used to maintain bubble stability without manual feed fluctuation. Batch-to-batch variance in melt flow can shift the frost line by several centimeters; the air ring and internal bubble cooling settings must be adjusted continuously when changing production lots.