HANWHA EVA 2315

In chemical foaming operations where EVA 2315 is the base resin, the compound exits a Banbury internal mixer at 105–115 °C and is transferred to a two-roll open mill with a nip gap of 2–4 mm before dicumyl peroxide approaches its scorch threshold near 150 °C. The nominal vinyl acetate content of 15 wt% determined per ASTM D5594 and the melt flow index of 2.0 g/10 min at 190 °C/2.16 kg per ISO 1133-1:2022 place this grade in the low-VA, medium-melt-strength window favoured for closed-cell footwear foam. A typical formulation charges EVA 2315 at 70–80 phr, calcium carbonate at 15–25 phr, azodicarbonamide at 2.5–4.0 phr, dicumyl peroxide at 0.6–0.9 phr, zinc oxide at 1.5–2.5 phr, and stearic acid at 0.5–0.8 phr. Batch-to-batch variation in melt flow index of ±0.3 g/10 min has been observed on production lots and is a known source of foam density drift; compounders commonly compensate by adjusting dicumyl peroxide within ±0.05 phr before the sheet-forming stage.

On a production line, the compounded sheet is fed to a hydraulic compression press with platens set at 155–165 °C; mold residence time is 8–12 min for sheet thickness between 10 mm and 30 mm, and pressure is held at 10–15 MPa. Typical failure modes observed at scale include edge blistering from residual moisture and centre-sheet over-cure from platen temperature gradients exceeding ±2 °C. For injection-foamed midsoles, a reciprocating-screw injection moulding machine with a clamp force of 3.5–5.0 kN/cm² projected area and screw L/D of 20:1–24:1 is used; barrel temperatures are profiled from 130 °C at feed to 150 °C at nozzle, and the mold is cooled at 35–50 °C to freeze the foam skin before ejection. Amine-based nucleating packages are avoided in this compound because they can shift azodicarbonamide decomposition to lower temperatures and increase scrap from premature blowing.

Conformity for crosslinked EVA foam articles is evaluated by apparent density according to ISO 845, compression set according to ASTM D395-18 Method B, tensile properties according to ISO 1798 or ISO 37:2017, and regulatory screening under REACH (EC) No 1907/2006 Annex XVII. Where the foam is used in consumer goods, volatile organic compound emissions are commonly tested under ISO 16000-6:2021, and footwear brands impose cadmium, lead, and phthalate limits aligned with REACH and California Proposition 65 consent judgments. Terminal product types from this scenario include running-shoe midsoles with apparent density in the 0.20–0.30 g/cm³ range, die-cut EVA insole boards, children's interlocking play mats, and sheet blanks for orthotic footbed milling.

How Does a 2.0 g/10 min Melt Index Modify Short-Shot Risk in Injection Moulding of Flexible Articles?

Injection moulding of EVA 2315 at 100 wt% is engineered around its 2.0 g/10 min melt flow index (190 °C, 2.16 kg, ISO 1133-1:2022) because this value restricts flow-length in thin-wall sections below 1.5 mm. The melt is processed at a barrel temperature profile from 155 °C to 180 °C, with nozzle temperature not exceeding 190 °C; at 180 °C the residence time is limited to 5–8 min to prevent vinyl acetate thermal degradation that generates acetic acid and increases mold deposit formation. For compounds requiring lower Shore A hardness, EVA 2315 is let down at 75–95 wt% with 5–25 wt% LDPE or EPDM, and a lubricant/processing aid package of 0.2–0.5 wt% is added. The antioxidant system is maintained at 0.1–0.3 phr of a hindered phenolic primary antioxidant with 0.1–0.2 phr of a phosphite secondary antioxidant to limit shear-induced degradation in the plasticating unit. Combination with secondary amine-based antistatic packages is avoided because amine residues accelerate acetic acid formation from the vinyl acetate comonomer at processing temperatures.

Production equipment for this resin consists of a reciprocating-screw injection moulding machine with screw L/D ratio of 20:1–25:1 and compression ratio of 2.2:1–2.6:1. Back pressure is held at 0.5–1.2 MPa, and injection speed is set to 30–60 mm/s for wall sections between 2 mm and 4 mm. Mold temperature is controlled at 20–40 °C; cooling time for 2 mm thick parts is 18–30 s. Operators on horizontal machines have recorded batch-to-batch viscosity variation of ±5% that can alter cushion part mass by 0.5–1.0 g, requiring verification with an in-line melt pressure transducer and adjustment of shot length by 2–4 mm.

The dimensional stability of moulded parts is evaluated under ISO 294-1 specimen preparation, tensile properties under ISO 527-2, and Shore A hardness under ISO 868. Because the resin is an ethylene-vinyl acetate copolymer, finished articles intended for the European market are assessed against REACH (EC) No 1907/2006 and RoHS Directive 2011/65/EU Annex II for lead, mercury, cadmium, hexavalent chromium, PBB, and PBDE. No phthalate plasticizer is inherent to EVA 2315, but external plasticizer additions are screened under REACH Annex XVII entry 51 if the article is a childcare article.

Typical terminal products in this scenario are machine foot pads, anti-slip furniture cups, flexible control-panel bezels, cable management grommets, and appliance sealing covers. These articles exploit the 15 wt% VA comonomer for low-temperature flexibility but are not specified for continuous service above 70 °C unless crosslinked, because compression set under ASTM D395-18 rises sharply when the surface temperature exceeds the softening range of the uncrosslinked resin.

EVA 2315 as a Low-VA Carrier Resin for Polyolefin Additive Masterbatch

In additive masterbatch production for polyethylene film and injection moulding, EVA 2315 serves as a carrier at 15–30 wt% of the masterbatch formulation; the remainder comprises the active additive at 40–60 wt%, a dispersing wax at 5–10 wt%, and an inert filler up to 20 wt%. The choice of EVA 2315 rather than a high-VA EVA is deliberate when head-space migration of vinyl acetate monomer into packaged goods is unacceptable; the 15 wt% VA content reduces polarity enough to maintain compatibility with LLDPE and HDPE let-down while avoiding excessive plate-out on chilled film rolls. The melt flow index of 2.0 g/10 min (190 °C, 2.16 kg, ASTM D1238) is low enough to survive strand pelletizing without molten strand breaks but high enough to distribute through a 40:1 L/D co-rotating twin-screw extruder at 300–450 rpm.

Compounding operations typically pre-dry the resin at 60 °C for 2 h when ambient relative humidity exceeds 60%; although EVA 2315 is not hygroscopic in the dry state, surface condensation in uncontrolled silos can introduce moisture-induced porosity in pellets. The twin-screw extruder temperature profile is set from 120 °C at the feed throat to 150 °C at the die plate, with melt temperature below 155 °C to avoid thermal decomposition of the acetate group. A melt pump and screen changer with 100-mesh screens are installed before a water-ring pelletizer; pellet intake water temperature is controlled at 20–30 °C to prevent pellet agglomeration. In production-scale runs, strand breakage has been linked to side-feeder output variation greater than ±2%, which is monitored by gravimetric feeders.

Compliance for masterbatch applications is governed by the end-use of the finished polyolefin article. The matrix below lists the applicable standards for common end uses.

Terminal outputs from this scenario are pelletized white and colour masterbatches for blown film extrusion, UV-stabilizer concentrates for agricultural twine and netting, antioxidant concentrates for nonwoven geotextiles, and processing-aid masterbatches used at 2–5 wt% let-down in LLDPE stretch film lines. The low VA content provides a narrower compatibility window with polypropylene; for PP-based masterbatches, EVA 2315 is not recommended above 10 wt% of the carrier package because phase separation has been observed on chill-roll surfaces as haze spots after 4–6 h of continuous casting.

When EVA 2315 Replaces LDPE in Low-Durometer Extrusion Profile Compounds

Extrusion compounds formulated with EVA 2315 at 55–70 wt%, LLDPE at 15–30 wt%, EPDM at 10–20 wt%, and calcium carbonate at 5–10 wt% are used to produce profiles that require Shore A hardness below 85 and compression set at 70 °C below 40% after 22 h per ISO 815-1:2019. The replacement of LDPE by EVA 2315 in this compound raises melt elasticity and reduces melt fracture at high drawdown because the 2.0 g/10 min MI (190 °C, 2.16 kg) reduces shear stress at the die lip compared with a fractional-MI LDPE. However, the low VA level of 15 wt% places a processing boundary at die temperatures above 170 °C; sustained melt temperatures in the adapter at 180 °C begin to generate acetic acid, and sintered metal breaker plates require cleaning after 72–96 h of continuous operation.

The production line uses a single-screw extruder with a screw L/D of 28:1–32:1 and a compression ratio of 2.5:1–3.0:1. Screen packs are arranged at 60/80/100 mesh, and the die body is maintained at 140–160 °C. After the die, the profile passes through a vacuum sizing tank with water at 15–25 °C and is cooled sufficiently to achieve surface hardness before cut-off; haul-off speed is set between 3 m/min and 8 m/min depending on profile cross-section. Operators at profile extrusion lines have reported that die-lip drool increases when the compound contains more than 0.5 wt% of free lubricant, so the lubricant package is normally split between 0.2–0.3 wt% calcium stearate and 0.1–0.2 wt% paraffin wax to avoid additive bloom on the finished profile within 48 h of cooling.

Conformity for these profiles is verified through tensile strength and elongation at break under ISO 37:2017, Shore A hardness under ISO 868, and compression set under ISO 815-1:2019. Regulatory review for industrial profiles sold into the EU includes REACH (EC) No 1907/2006 Annex XVII and, for electrical enclosure gaskets, RoHS Directive 2011/65/EU Annex II. No food-contact declaration is made for this compound class unless the downstream converter performs migration testing on the finished gasket under EU 10/2011 simulant B.

Terminal profile products include HVAC flange gaskets, refrigeration door seals, impact-absorbing furniture edge protectors, expansion joint strips for interior partitions, and low-torque cable bushings for automotive wiring harness routing. Each of these products benefits from the low-temperature flexibility of the 15 wt% EVA co-monomer, but continuous exposure above 70 °C is not advised for uncrosslinked grades because the compression set rises to 60–80% after 22 h at 80 °C.

Calendered sheet extrusion using EVA 2315 at 70–85 wt% with a low-density polyethylene or polyolefin elastomer at 10–20 wt% and a hindered phenolic/phosphite stabilizer package at 0.1–0.3 wt% is a downstream route for thermoformable padding and laminated board stock. The resin's 15 wt% vinyl acetate content is sufficient to reduce calender plate-out compared with higher-VA EVA grades, but it remains below the threshold where sheet blocking becomes a storage problem in hot warehouses. At the calender, a four-roll inverted-L configuration is operated with roll temperatures of 115–130 °C at the first nip and 100–115 °C at the final nip; line speeds are maintained at 8–20 m/min for sheet thickness from 0.5 mm to 3.0 mm. The melt film is transferred to a cooling drum at 20–30 °C, and edge trim is returned to the feed at 5–15 wt% regrind without causing measurable melt fracture when the regrind particle size is below 10 mm.

Process audits for this sheet format focus on gauge variation, which must be controlled within ±0.05 mm for sheet below 1.0 mm to prevent thermoforming thin spots. The roll gap is checked after every 8 h shift because bearing temperature drift of 5–10 °C can change the gap by 0.03–0.08 mm in older calender configurations. Product compliance is verified by apparent density according to ISO 1183-1:2019, tensile properties of sheet according to ISO 527-3:2018, and regulatory screening under REACH (EC) No 1907/2006; when the sheet is used in child-facing products, EN 71-3:2019+A1:2021 migration limits for barium, cadmium, and lead apply to the pigmented compound.

Terminal product types produced from this sheet include thermoformed insole blanks, die-cut backpack padding panels, protective case linings, and structural counter material for footwear. Calendered EVA 2315 sheet is not specified for direct skin-contact medical applications because the polymer has no ISO 10993 biocompatibility designation; such applications would require additional extractables and leachables data generated on the finished sheet under ISO 10993-18:2020.

Impact Modification of Post-Consumer Polyethylene Using 15 wt% VA Ethylene-Vinyl Acetate Blends

Blending EVA 2315 at 10–25 wt% into post-consumer HDPE or LLDPE feedstock is performed on co-rotating twin-screw compounding lines to recover notched impact strength lost during thermal recycling. The VA comonomer at 15 wt% is lower than grades used in elastomeric toughening, so the modification is classified as a process-compatible viscosity and stress-cracking additive rather than a rubber replacement; published data specific to EVA 2315 in mixed post-consumer PE streams is limited, and compounders validate the exact addition level by running response-surface trials on each lot. In a twin-screw extruder with an L/D of 36:1–44:1, the blend is processed at 160–210 °C with EVA 2315 fed into the main throat and recycled PE metered downstream to limit residence time of recycled fines. A melt pump maintained at 1.5–3.5 MPa inlet pressure stabilizes strand pelletizing at 200–400 rpm screw speed.

The resulting compound is evaluated under ASTM D638-14 tensile properties, ISO 179-1:2010 Charpy notched impact at 23 °C, and melt flow index per ISO 1133-1:2022. At 20 wt% EVA 2315, typical recycled HDPE compounds show an increase in Charpy notched impact of 8–15% relative to unmodified recycled resin, and the melt flow index shifts by 0.5–1.5 g/10 min depending on the carrier polymer; these values are process-lot dependent and should not be interpreted as fixed product specifications. Regulatory compliance follows REACH (EC) No 1907/2006 and RoHS Directive 2011/65/EU for hazardous substance restrictions; because post-consumer PE lots may contain legacy contaminants, incoming feedstock is screened by X-ray fluorescence for cadmium and lead before compounding.

Terminal articles produced from this compound are blow-moulded recycling bins and agricultural chemical drums, injection-moulded tote boxes, and extruded corner protectors for concrete precast panels. EVA 2315 is not effective at improving low-temperature impact below -20 °C in HDPE-rich streams because the 15 wt% VA content does not provide sufficient rubber-phase cavitation; for service temperatures below -20 °C, an EPDM or ethylene-octene modifier should replace part of the EVA 2315 addition.