HANWHA EVA 1317

Compounding of a chemically blown crosslinked closed-cell foam from HANWHA EVA 1317 begins with pellet pre-blending in a low-shear tumble mixer. Published technical data for this grade list a vinyl acetate content of 18 wt% under ASTM D5594 and a melt mass-flow rate of 1.7 g/10 min at 190°C/2.16 kg under ASTM D1238, placing the material in the high-viscosity branch of EVA foam resins. On production two-roll mills with roll surface temperatures maintained at 105–115°C, the first processing boundary is scorch: dicumyl peroxide with a 1-minute half-life near 171°C must be added only after fillers and blowing agent are dispersed, and compound temperature must not exceed 110°C for more than 8 min before peroxide addition. A typical industrial preform uses EVA 1317 at 100 phr, azodicarbonamide at 4.0–8.0 phr, dicumyl peroxide at 0.4–1.0 phr, zinc oxide at 1.0–3.0 phr, stearic acid at 0.5–1.0 phr, and calcium carbonate at 10–40 phr; the zinc oxide and stearic acid combination functions as a blowing-agent activator and processing lubricant rather than as an inert filler package. Calendered preforms are compression-moulded at 150–170°C under 10–15 MPa platen pressure for 10–20 min depending on thickness. Foam density is typically reduced to 0.10–0.20 g/cm³, while hardness measured on the formed skin under ASTM D2240 type D remains in the 35–45 range before any post-treatment. The dominant failure mode on automated lines is split-cell tear when the gas-expansion rate outpaces crosslink modulus build-up; this is controlled by staging the ram pressure downward with a bleed cycle before the crosslink plateau. Batch-to-batch variance in calcium carbonate particle size distribution shifts the apparent cure torque measured on a rotorless curemeter under ASTM D5289; when median particle size moves above 3 µm, the formulation usually requires a 0.1 phr dicumyl peroxide upward adjustment to maintain cell-wall strength. Thermal degradation above 220°C releases acetic acid and must be avoided because the acid accelerates mould corrosion and causes surface tack on the expanded sheet.

Injection Molding of Compact Footwear Components

Direct injection moulding of compact footwear unit soles from EVA 1317 is selected where flex-fatigue resistance and abrasion service are more critical than expanded-foam cushioning. The melt mass-flow rate of 1.7 g/10 min produces high injection-pressure demand; reciprocating-screw machines with 20:1 L/D barrels and check-ring shutoff are preferred over general-purpose machines. Barrel zone set points are typically profiled from 170°C at the feed throat to 190–200°C at the nozzle, while the mould wall is held at 25–40°C to balance flow length against post-demoulding shrinkage. Injection pressure at the screw tip commonly settles in the 80–120 MPa band for thick-wall soles, and clamp force is calculated from projected area rather than part volume. Short-shot adjustment is performed by increasing injection speed before raising melt temperature because exposure above 210°C promotes acetic acid evolution from the vinyl acetate segments; the acid deposits on mould vents and causes gas-burn marking at the flow front. The compact formulation typically blends EVA 1317 with 5–20 phr of high-pressure LDPE or EPDM to keep flexural modulus below 80 MPa and to improve gate blush resistance. Dimensional stability is assessed by measuring post-mould shrinkage after 48 h at 23°C/50% RH; values above 1.5% in the flow direction normally indicate insufficient packing pressure or premature gate freeze. Tear strength under ASTM D624 Type C is the governing lab test for outsole flex grooves; compounds intended for athletic unit soles are typically rejected when tear strength falls below the brand specification because groove-initiated tear propagates within 5,000 flex cycles. Pre-drying at 60°C for 2–4 h is applied only when pellet surface moisture exceeds 0.10% or when condensation is observed after cold-weather storage, since EVA 1317 is not hygroscopic enough to justify automatic desiccant drying on every cycle.

What Moisture Boundary Applies Before Single-Screw Profile Extrusion?

Dense, non-foamed EVA profiles based on EVA 1317 are processed on single-screw extruders with 24:1 L/D and a 3:1 compression-ratio screw, frequently with a grooved feed throat and a 40/60/40 mesh screen pack. The moisture boundary is operational rather than intrinsic: surface condensation from cold pellet storage causes pitting and die-swell irregularity, while the 18 wt% vinyl acetate content does not create hygroscopic viscosity shifts. When pellets are moved from storage below 10°C into a warm compounding hall, a hopper dryer at 60°C for 2 h removes surface film. Moisture levels above 0.15% measured by coulometric Karl Fischer titration produce surface splay and irregular die swell; drying is stopped below 0.05%. For dense profiles the compound often includes 20–40 phr calcium carbonate or talc, but talc above 30 phr lowers tear strength and increases die lip plate-out. EVA 1317 is not a direct substitute for EPDM in exterior automotive glazing profiles unless UV absorber and hindered-amine light stabiliser packages are loaded above the typical 0.3–0.5 wt% and validated under ISO 4892-2 to at least 1,000 h. The acetic acid released by thermal degradation above 220°C corrodes unplated steel calibrators; vacuum calibration tanks downstream should therefore be constructed from stainless steel or nickel-plated brass. Hardness and compression set are measured under ISO 868 and ISO 815-1; dense gasket compounds are typically formulated to 60–70 Shore A because lower hardness causes installation buckling and higher hardness reduces conformability at low-closure-force joint designs.

Blending EVA 1317 into LLDPE and LDPE film structures is performed on co-rotating twin-screw extruders with 40:1 L/D, not on single-screw dry-side equipment, because the 18 wt% vinyl acetate domains must be dispersed below 1 µm to improve dart impact without unacceptable haze. In LLDPE film, addition of 5–15 wt% EVA 1317 raises environmental stress-crack resistance as measured by ASTM D1693 Condition B; the improvement is attributed to the elastomeric amorphous phase and to reduced crystalline tie-chain stress. Specific haze values depend on LLDPE comonomer type and film gauge, and published data for this exact formulation is limited, so pilot-film trials on a cast-film line at melt temperatures below 200°C are recommended. In post-consumer mixed polyolefin streams, EVA 1317 at 5–10 wt% acts as an interfacial impact modifier rather than a true compatibiliser; notched Izod under ISO 180/A can recover to a level governed by the HDPE-to-PP ratio and stream contamination, but published data for this specific EVA 1317 recycle configuration is limited. Above 15 wt% addition, tensile modulus declines and die-face build-up appears on strand pelletizers. Gel count is checked under ASTM D3351 because EVA oxidation generates crosslinked gel particles above 210°C. This grade is not suitable for low-viscosity hot-melt adhesive systems; its melt viscosity at 180°C is too high for tank-applied packaging adhesives, and higher-melt-index EVA grades are specified for that application.

When EVA 1317 Is Used as a Carrier for High-Loading Polyolefin Colour Masterbatch

EVA 1317 is used as a pigment carrier where high filler wetting and low processing dilution are required, especially for polyolefin-based masterbatch compounded on co-rotating twin-screw extruders at 40–60% pigment loading. The 18 wt% vinyl acetate content reduces melt surface tension and improves pigment agglomerate wetting compared with LDPE carriers; the 1.7 g/10 min melt flow rate increases torque and melt pressure, so screw designs with distributive mixing elements and oil heating are preferred over flying-wing rotor geometries. Compounding temperatures are held between 170°C and 190°C; higher temperatures initiate acetic acid release, which attacks carbon black dispersion and lowers pH-sensitive pigment chroma. For carbon black masterbatches, loading of 45–50 wt% is attainable on 40:1 L/D twin-screw lines, but pressure drop across the die plate can exceed 12 MPa when screen packs are below 40 mesh. The finished masterbatch is characterized by filter pressure value under EN 13900-5 and dispersion under ISO 18553; masterbatch producers typically require an FPV below 0.2 bar/g and a dispersion rating of B or better. The limitation is carrier rheology: a carrier with melt flow rate below 2 g/10 min dilutes slowly in thin-wall film-grade LLDPE, so EVA 1317 should not be used for masterbatches destined for films below 30 µm unless a lower-molecular-weight co-carrier is added.