HANWHA EVA 1815

Hanwha EVA 1815, a nominal 18 wt% vinyl acetate copolymer with a melt flow rate of 1.5 g/10 min when tested under ASTM D1238-20 at 190°C and 2.16 kg, functions as the primary resin in crosslinked closed-cell footwear midsole compounds. The applicable compliance framework for this route includes ISO 7214:2012 for flexible cellular polyolefins and ASTM D3575 for olefinic foam physical properties, while export specifications are additionally reviewed against REACH (EC) 1907/2006 Annex XVII polycyclic aromatic hydrocarbon restrictions and RoHS 2011/65/EU where embedded electronic components are present. A typical starting formulation places Hanwha EVA 1815 at 100 phr, azodicarbonamide at 1.8–2.6 phr, dicumyl peroxide at 0.6–1.0 phr, zinc oxide at 0.8–1.2 phr, stearic acid at 0.5–0.8 phr, and calcium carbonate at 0–15 phr. The production sequence begins in an internal mixer with ram pressure between 0.5 MPa and 0.7 MPa and a batch drop temperature of 105–115°C, followed by a two-roll mill set at 90–100°C to avoid premature crosslinking or blowing agent decomposition. The pelletized compound is then compression-molded at 160–175°C for 8–12 min or injection-foamed in a reciprocating screw machine with clamp force matched to the projected area of the midsole cavity. In injection foaming, the melt flow rate of 1.5 g/10 min restricts flow length in thin sections, so runner diameters are increased and the mold is filled with a short-shot technique that permits expansion rather than packing. Terminal product types include athletic shoe midsoles, casual footwear insoles, and flip-flop soles. The principal thermal boundary is deacetylation: prolonged melt residence above 200°C accelerates acetic acid release, corrodes mold surfaces, and produces yellowing, so barrel-temperature profiles are capped at 190°C and screw recovery is staged to avoid stagnant melt zones.

The crosslinking and foaming sequence in this grade operates inside a narrow kinetic window. Azodicarbonamide decomposition onset occurs between 205°C and 215°C, while dicumyl peroxide exhibits a half-life of approximately 1 min at 171°C. If mold temperature is too low, dicumyl peroxide does not generate sufficient free radicals before gas nucleation, producing partially fused boards with poor tear resistance and high compression set. If mold temperature exceeds 180°C, melt viscosity drops rapidly and expanding gas ruptures cell walls, increasing open-cell content and causing irreversible shrinkage after demolding. Production-scale failure modes include density variation of ±0.02 g/cm³ when two-roll mill temperature deviates by more than 5°C, because the blowing agent and peroxide become unevenly distributed. Compression set is measured according to ASTM D395-18 and hardness according to ASTM D2240-15; midsoles produced from Hanwha EVA 1815 typically require post-foaming stabilization at 50–60°C for 24–48 h before dimensional stability is sufficient for downstream assembly.

What Limits the ATH Loading Window in Halogen-Free Sheathing Compounds?

In low-smoke zero-halogen cable sheathing, Hanwha EVA 1815 is compounded with precipitated alumina trihydrate and magnesium dihydrate rather than processed as a neat polymer. The 18 wt% vinyl acetate content reduces crystalline spherulite density enough to improve filler wetting compared with LDPE, while the melt flow rate of 1.5 g/10 min provides sufficient melt strength for tube-on sheathing dies. Industry compliance is anchored to IEC 60332-1-2 for vertical flame propagation on single insulated wires or cables, IEC 60754-1 for halogen acid gas release, and IEC 60754-2 for pH and conductivity of combustion gas effluent; regional cable standards such as EN 50363-5 define the compound categories used in low-voltage energy cables. A production starting formulation places Hanwha EVA 1815 at 25–35 wt%, alumina trihydrate at 50–60 wt%, magnesium dihydrate at 10–15 wt%, a maleic anhydride-grafted polyolefin compatibilizer at 2–5 wt%, hindered phenolic antioxidant at 0.5–1.0 wt%, and UV stabilizer or carbon black at 2–3 wt%. The compounding route uses a co-rotating twin-screw extruder with an L/D ratio of 40–52:1 and downstream side feeding of mineral filler after the polymer melt seal. Barrel zones are maintained from 120°C to 180°C, and melt temperature is monitored before the strand die at 180–200°C. Above 65 wt% total mineral loading, production-scale behavior shifts from stable strand pelletizing to die-face pressure oscillation, screen-pack blinding, and surface melt fracture. Moisture carried into the extruder by alumina trihydrate vaporizes at the melt seal and generates pinholes in the pellets, so the line is operated with atmospheric and vacuum venting, and the side-feeder hopper is fitted with a nitrogen purge when ambient relative humidity exceeds 60%. After compounding, pellets are extruded onto cable in a single-screw sheathing line with a compression ratio of 2.5–3.0:1 and a tube-on or pressure die. Terminal product types include halogen-free sheathing for control cables, building wire jackets, and data-communication cable jackets where low smoke and low acid gas emission are specified.

Coextrusion Tie-Resin Melt Strength and Adhesion to Aluminum Foil

Coextrusion tie layers for aluminum foil and oriented polypropylene structures have been formulated with Hanwha EVA 1815 to improve substrate wetting and peel adhesion without shifting to a higher-VA EVA that may reduce thermal resistance. The compliance framework for food-contact laminates is 21 CFR 177.1350 and EU 10/2011, and peel adhesion is measured according to ASTM D1876. The addition ratio in an LDPE-based tie layer is 10–20 wt% Hanwha EVA 1815; above 20 wt%, melt strength declines enough to create draw resonance on extrusion lamination lines. The downstream process uses a tandem extrusion lamination line with an air gap of 10–20 cm, a chilled nip roll at 15–25°C, and a slot die gap of 0.5–1.2 mm. Melt temperature is capped at 200–220°C to limit acetic acid evolution while maintaining adhesion to aluminum foil. Terminal product types include multilayer barrier laminates, cable insulation wrap, and foil-backed technical tapes. A production boundary is the low melt flow rate of Hanwha EVA 1815: at higher line speeds, edge neck-in and gauge variation typically require the addition of a higher-MI LLDPE or a reduction in EVA 1815 content.

In high-filler masterbatch production, Hanwha EVA 1815 is evaluated as a carrier resin because the 18 wt% vinyl acetate content improves pigment and mineral filler wetting relative to LDPE carriers while maintaining compatibility with polyolefin let-down streams. Compliance for masterbatch shipped into the EU is managed under REACH (EC) 1907/2006 and, for electrical or electronic end uses, RoHS 2011/65/EU. The carrier content of a production masterbatch is 30–50 wt% Hanwha EVA 1815, with filler or pigment at 50–70 wt% and processing lubricant at 0–2 wt%. The compound is processed on a co-rotating twin-screw extruder with an L/D ratio of 40:1 or higher, side feeding of filler after polymer melting, atmospheric venting, and a vacuum vent before the die. Die-face cutting is preferred over strand pelletizing when filler loading exceeds 65 wt%, because the melt strand becomes brittle and tends to shatter in a water bath. Terminal product types include color masterbatches for polyethylene film, flame-retardant masterbatches, and nucleating agent masterbatches. The operational boundary is thermal: the carrier has a lower melt flow rate than typical masterbatch carriers, so screw speed and feed rate must be balanced to avoid melt temperatures above 190°C and the associated acetic acid odor.

Calendering-Induced Density Stratification in Crosslinked Sheet Foam Requires Two-Stage Oven Control

When Hanwha EVA 1815 is converted into crosslinked closed-cell sheet foam, the process differs from footwear injection molding because the blowing agent is expanded after sheet formation, not inside a closed mold. The relevant compliance standards are ASTM D1056-14 for flexible cellular materials and ISO 7214:2012 for flexible cellular polyolefins. A calender-grade formulation starts at 100 phr Hanwha EVA 1815, azodicarbonamide at 1.5–2.5 phr, dicumyl peroxide at 0.6–1.0 phr, zinc oxide at 0.5–1.0 phr, and calcium carbonate at 5–20 phr to adjust cell nucleation and reduce surface tack. The production sequence uses an internal mixer, a two-roll mill, and a calender with roll temperatures between 85°C and 95°C; the sheet is then cut to dimension and expanded in a hot-air curing oven at 170–190°C. Sheet thickness above 10 mm creates a through-thickness temperature gradient, and the center of the sheet can reach foaming temperature 30–60 s after the surface, producing density stratification and crown imperfections. Production-scale corrective actions include reducing oven air velocity at the sheet surface and using a two-stage temperature profile with a first plateau at 160°C for peroxide cure initiation. Terminal products include marine buoyancy sheets, HVAC gasketing, thermal insulation pads, and sports matting. The lower melt index of Hanwha EVA 1815 supports sheet integrity during expansion but also increases calender roll separating force; roll gap must be recalibrated when ambient temperature falls below 15°C because the compound stiffens and feeds unevenly.

A hot melt formulation based on Hanwha EVA 1815 differs from higher-VA EVA grades in open time and cohesive strength because the 18 wt% vinyl acetate content leaves higher crystallinity in the base polymer. The adhesive is evaluated for heat-fail temperature under ASTM D4498-07, and for food packaging uses the formulation must not exceed overall migration limits under EU 10/2011 where indirect food contact is possible. A starting addition ratio places Hanwha EVA 1815 at 25–35 wt%, a C5 or hydrogenated hydrocarbon tackifying resin at 30–45 wt%, microcrystalline wax at 15–25 wt%, and hindered phenolic antioxidant at 0.5–1.0 wt%. The production process uses a jacketed sigma-blade mixer or continuous screw mixer at 150–170°C under a nitrogen blanket, followed by a gear pump and slot-die or roll coater. Because the melt flow rate is 1.5 g/10 min, formulation viscosity is high at typical hot-melt application temperatures below 160°C; wax addition is therefore increased relative to a higher-VA EVA grade, and the coating line is run with a heated hose setpoint 10–20°C above the reservoir temperature. Terminal product types include case sealing, carton closing, and bookbinding adhesives. Published production data for this specific grade in hot melt adhesives is limited compared with higher-VA EVA grades, so viscosity-temperature profiling on the actual application equipment is required before replacing an existing EVA grade.

When EVA 1815 Replaces LDPE in Flexible Packaging Sealant Layers

When Hanwha EVA 1815 replaces a neat LDPE sealant layer in a multilayer flexible packaging structure, the technical basis is a measurable reduction in heat-seal initiation temperature because the vinyl acetate comonomer interrupts crystallite formation. The relevant food-contact framework is 21 CFR 177.1350 in the United States and EU 10/2011 in the European Union, and heat-seal strength is measured according to ASTM F2029-16 after a flat-jaw seal dwell of 0.5–1.0 s. The replacement is not made at 100% Hanwha EVA 1815 in most high-speed packaging lines; the blend addition ratio is 10–30 wt% Hanwha EVA 1815 in LDPE or LLDPE, or a two-layer coextrusion in which an EVA 1815-rich skin at 20–40 wt% is carried by a stiffer polyolefin core. The downstream process is a blown film or cast film line with a die temperature of 190–210°C, a blow-up ratio of 2.0–3.0, and frost line height adjusted upward by 10–20% compared with LDPE to compensate for slower crystallization. Terminal product types include frozen food films, bakery film sealant webs, and medical pouch lidding. The operational boundary is that Hanwha EVA 1815 sealant layers are not suitable for retort or high-temperature sterilization above 121°C because softening and blocking can occur, and the melt flow rate of 1.5 g/10 min demands a wider die gap and reduced line speed when skins are produced below 25 µm unless the grade is blended with a higher-MI LLDPE.