Greenflex ML 60 BCA EVA Copolymer Resin,Atribuído Bio-Circular,Grado de espuma de alta elasticidade

Greenflex ML 60 BCA is handled in downstream foaming operations as a bio-circular attributed EVA copolymer resin. The bio-circular attribution is maintained under ISCC PLUS or REDcert² mass-balance documentation and does not alter melt flow rate, vinyl acetate distribution, or peroxide cure kinetics relative to the fossil-equivalent grade within normal lot-to-lot variation. Published data for this exact bio-circular attributed configuration are limited; processing windows are therefore drawn from EVA foam grades of equivalent vinyl acetate content 18–21 wt% and melt flow rate 5.5–6.5 g/10 min at 190 °C/2.16 kg per ISO 1133-1:2022.

When Expanding Midsoles Requires Rebound Above 52% and Density Below 0.25 g/cm³

Running-shoe midsoles are compression-moulded with dual-zone platens held at 165–175 °C. The compound is converted on an open mill or in a Banbury internal mixer before being pelletised into preforms. Viscosity drift between batches must remain below ±8% because the nucleation window of azodicarbonamide is narrow. A representative midsole compound uses resin 100 phr, azodicarbonamide 2.5–4.0 phr, dicumyl peroxide 0.8–1.1 phr, zinc oxide 1.0–1.8 phr, zinc stearate 0.5–0.9 phr, and optional calcium carbonate 5–15 phr. Dicumyl peroxide undergoes thermal homolysis with a half-life of approximately 1 min at 171 °C. Crosslinking and gas generation must overlap inside the mould cavity between 165 °C and 175 °C. If the peroxide network forms too early, expansion is restricted and density remains above 0.30 g/cm³. If blowing agent decomposition outpaces crosslinking, trapped gas escapes through melt channels and large open cells appear. The foam is expanded to 1.8–2.2 times its original thickness, yielding density 0.18–0.22 g/cm³.

Multi-cavity presses with 250–500 kN clamp force are common on production lines. PTFE-coated cavities and weekly alkaline cleaning are required to control azodicarbonamide residue fouling that reduces heat transfer and causes sticking. Demoulding occurs below 50 °C to prevent post-mold cell relaxation and shrinkage. Post-cure aging for 24–48 h at 23 °C/50% RH stabilises dimensional change before assembly. The finished midsole should exhibit rebound 52–58% by ASTM D2632 or ISO 8307, tensile strength ≥2.0 MPa and elongation ≥250% per ISO 1798, and compression set 25–35% after 24 h at 50 °C under ASTM D395 Method B. The moulded midsole is subsequently bonded to outsole rubber and upper mesh by cementing or direct injection.

Why Closed-Cell Integrity Determines Buoyancy Service Life in Saltwater Exposure

Marine buoyancy foam is produced in slab form at density 0.05–0.10 g/cm³. Closed-cell content must remain above 90% to preserve buoyancy after prolonged immersion. The compound uses resin 100 phr, azodicarbonamide 6.0–10.0 phr, dicumyl peroxide 0.5–0.9 phr, and zinc oxide 1.5–2.5 phr. Calcium carbonate is excluded because filler particles open channels for water ingress and increase apparent density after immersion. Single-shot compression moulding ramps at 5 °C/min to 160 °C. Core temperature is monitored with embedded thermocouples, and pressure is held until the core falls below 60 °C. Premature pressure release generates internal splits that become capillary pathways for saltwater absorption. Buoyancy aids conforming to ISO 12402-5 require the foam not to absorb more than 1% volume water after 24 h submersion.

Published data for this exact BCA marine configuration are limited. Saltwater ageing values are therefore based on equivalent VA content EVA foam materials, which typically retain tensile strength above 80% after 500 h immersion at 40 °C. Long-term UV exposure requires carbon black or UV-stabilised pigments to avoid surface chalking. VA contents above 26 wt% should be avoided because hydrolysis rate increases with vinyl acetate content. End products include buoyancy layers inside personal flotation devices, marine impact pads, and closed-cell fender inserts.

Flat-sheet foaming lines for fitness and yoga mats operate with a narrower expansion window than midsole moulding. The compound is formulated at resin 100 phr, azodicarbonamide 3.0–5.5 phr, dicumyl peroxide 0.6–1.0 phr, zinc stearate 0.5–1.0 phr, and talc 5–10 phr to control surface tack. The sheet is expanded in a single-shot press at 150–165 °C and passed through cooling rollers set at 15–20 °C to fix cell geometry before embossing. Residual blowing agent content becomes the primary regulatory constraint. Azodicarbonamide decomposition leaves hydrazodicarbonamide residues, and consumer mats sold in the European Union must comply with REACH Annex XVII entry 50 for PAH limits and, when marketed for children, with EN 71-3 migration limits. Indoor air emission is quantified by chamber testing based on ISO 16000-6. Static charge accumulation on cooled sheets causes dust pick-up; inline ionizing bars are installed before winding. Finished mats are supplied at 3–8 mm thickness and 0.10–0.16 g/cm³ density.

Orthotic Foam Densification and Skin Contact Compliance Architecture

Orthotic accommodative cushioning uses the foam at 0.15–0.25 g/cm³ and Shore A 30–45. The resin is compounded at 100 phr with azodicarbonamide 2.0–3.5 phr, dicumyl peroxide 0.7–1.0 phr, zinc oxide 1.0 phr, and calcium carbonate 0–8 phr to adjust hardness without increasing skin-contact leachables. Sheets are compression-moulded at 160–170 °C and cooled under pressure to below 50 °C before demoulding. Gel fraction after cure must exceed 85% by xylene extraction according to ASTM D2765. Higher gel fraction reduces extractables and improves dimensional stability. Water-jet cutting of low-gel foam creates ragged cell walls; cured foam with gel fraction above 85% cuts cleanly and retains edge integrity in contoured orthoses. Biocompatibility is assessed under ISO 10993-5 and ISO 10993-10; extractables are prepared per ISO 10993-12. Products are classified under EU MDR 2017/745 as Class I devices when no therapeutic claim is made. Ester plasticizers should be avoided because migration can cause skin sensitisation. Amine-based stabilizers scavenge peroxide radicals and reduce gel fraction. The BCA mass-balance attribution does not waive lot-specific medical-grade testing. End products include orthotic insoles, brace liners, and accommodative padding in diabetic footwear.

Impact protection pads require transmitted force management, not simply density reduction. Elbow and knee protectors conforming to EN 1621-1:2012 are expanded to 0.12–0.18 g/cm³ with closed-cell content above 90% and thickness 10–20 mm. The compound is based on resin 100 phr, azodicarbonamide 4.0–6.0 phr, dicumyl peroxide 0.8–1.2 phr, zinc oxide 1.5–2.0 phr, and EPDM 15–25 phr to raise tear resistance under high-rate loading. Compression moulding is performed at 165–175 °C under 200–400 kN clamp force. Cooling below 45 °C before ejection prevents post-mold expansion and internal split planes. Azodicarbonamide loading above 6.0 phr can create internal voids that increase transmitted force. Under EN 1621-1:2012 Level 1, transmitted force must remain below 35 kN average, with no single specimen above 50 kN. Static rebound values above 55% do not guarantee impact attenuation because energy absorption is rate-dependent. End products include limb protectors, chest padding, and damping inserts for sports equipment.

Compression set below 12% is the controlling parameter in automotive interior foam

Automotive interior foam based on this resin is used in door armrests, knee bolsters, headrest inserts, and sun visor padding. The dry-blend formulation contains resin 100 phr, azodicarbonamide 2.5–4.0 phr, dicumyl peroxide 0.8–1.2 phr, zinc oxide 1.0–2.0 phr, and aluminium trihydrate 15–25 phr where FMVSS 302 flame retardancy is required. ATH loadings above 25 phr raise density and reduce rebound below 35%. Fine particle ATH with an average particle size of 2–5 µm is preferred to limit melt viscosity increase. Slabstock or in-mold foaming is run at 160–175 °C. Non-silicone mould release agents are mandatory because low-molecular siloxanes transfer to windshield glass and increase fogging. Fogging is tested per ISO 6452, with gravimetric deposit limits commonly below 5 mg per OEM specification. VOC release is measured by VDA 277, interior emissions by VDA 278, and odour is graded to VDA 270 with a typical requirement of ≤3 for visible interior parts. Burn rate per FMVSS 302 must be below 100 mm/min. Halogenated flame retardants are restricted by OEM prohibited substances lists; ATH or magnesium hydroxide is used at minimum loading to retain compression set below 12%.