LG EVA 15006 Ethylene Vinyl Acetate Copolymer

In blown film extrusion of 15 wt% vinyl acetate copolymer, LG EVA 15006 functions as a high-molecular-weight film former with a melt mass-flow rate of 0.6 g/10 min under ISO 1133-1:2022 conditions at 190 °C and 2.16 kg, and a nominal density of 0.940 g/cm³ under ISO 1183-1. The resin is normally pre-dried at 60–70 °C for 3–4 h in a desiccant dryer to reduce moisture below 0.05 wt%, because residual water generates bubbles and surface defects during bubble expansion. On a single-screw blown film line with an L/D ratio of 24:1 to 30:1 and a compression ratio of 2.5:1, the barrel temperature profile moves from 140–150 °C in the feed zone to 185–195 °C at the die head. The die gap is maintained at 0.8–1.5 mm, and a blow-up ratio of 2.0–2.5:1 is typical for this grade because the low MFR provides sufficient melt tension to avoid bubble flutter. Frost line height should be kept within 4–8 die diameters to balance optical haze and dart impact resistance. Film tensile properties are measured under ASTM D882; dart impact is tested under ASTM D1709 method A, and Elmendorf tear is measured according to ASTM D1922. The addition of slip and antiblock concentrates is often required because EVA film surfaces exhibit higher blocking tendency than LDPE at chill roll temperatures above 25 °C. Typical applications for this grade in blown film include frozen food overwrap, liquid pouch laminates, and agricultural side curtains where lower heat-seal initiation relative to LDPE reduces dwell time on horizontal form-fill-seal machines. The primary processing failure modes on production equipment are bubble chatter caused by inadequate melt temperature uniformity, die lip buildup from oxidized EVA at the die exit, and melt fracture on low-friction die surfaces when line speeds exceed the shear stress limit of the resin. These failure modes are managed by reducing die exit temperature, increasing die gap, or adding a fluoropolymer processing aid at 0.05–0.15 wt%.

Why Does a Melt Flow Index of 0.6 g/10 min Raise Melt Pressure in Extrusion Coating Dies?

Extrusion coating of flexible substrates with LG EVA 15006 is constrained by the same high melt viscosity that benefits blown film bubble stability. When the resin is processed through a coat-hanger die with a die gap of 0.5–0.8 mm, the low melt flow index generates higher shear stress at the die lip compared with a 7 g/10 min LDPE coating grade, and the resulting melt pressure can approach the transducer alarm limit if the die is operated below 260 °C. Melt temperature at the adapter is normally held at 240–260 °C, while the chill roll is controlled at 15–25 °C and the air gap is set at 150–250 mm. Coating weights for EVA 15006 in flexible packaging generally fall between 15 g/m² and 30 g/m², and line speeds above 150 m/min are typically avoided with unfilled formulations because draw resonance and edge weave appear when the melt curtain is thinned beyond its critical draw ratio. Adhesion to aluminum foil and corona-treated polyethylene is strongly influenced by the oxidation state of the melt curtain and substrate temperature; in-line corona treatment at 2–4 kW per metre of web width is sometimes used when the EVA is the outer layer. For food-contact lamination, the finished structure must be evaluated under 21 CFR 177.1350 or relevant regional migration limits, while heavy-metal content is verified against EU 10/2011 migration testing. The principal production failure mode is die deposit, which accumulates as crosslinked gel particles on the die exit lip after extended runs at tip temperatures above 275 °C. The low-RPM screw torque is generally not the bottleneck; rather, the shear heating generated at the metering zone can exceed the set point by 10–15 °C if a barrier screw with excessive compression ratio is used. To suppress draw resonance, an extruder with a 25:1 L/D barrel and a gear pump can be deployed, but the pump must be maintained above 180 °C because EVA 15006 has a high viscosity and can overpressurize cold clearances.

When Dicumyl Peroxide and Azodicarbonamide Compete in Crosslinked EVA Foam Expansion

Crosslinked closed-cell foam produced from EVA 15006 requires simultaneous control of dicumyl peroxide decomposition kinetics and azodicarbonamide gas release kinetics. The base polymer is milled on a two-roll mill at 95–105 °C with the blowing agent, crosslinker, kicker, and lubricant. On a 75-L internal mixer, the fill factor is maintained at 70–80% and ram pressure at 4–6 bar; dump temperature should not exceed 110 °C. If the compound is advanced too far during mixing, scorch occurs because dicumyl peroxide begins to decompose at temperatures above 125 °C; the resulting gel specks cannot be dispersed and remain visible in the final foam sheet. A typical production formulation for athletic mats and structural footwear midsoles is shown in the table. The expansion ratio is highly sensitive to the crosslink-to-blow timing window. When the crosslink density develops too early, the melt strength exceeds foam expansion pressure and density remains above 0.25 g/cm³; when blowing gas is released before a gel network forms, cell walls rupture and the sheet collapses. In a 1,000-tonne compression press, preheating at 110–120 °C for 8–12 min is followed by pressure release and expansion at 155–165 °C for 10–15 min. Foam density is measured according to ISO 845, compression set under ASTM D395 method B, and gel content by extraction under ASTM D2765 method A; typical gel content values for this type of foam are 60–80%. The cellular structure is inspected at 20–40× magnification for average cell diameter and sidewall integrity. Applications of EVA 15006 foams are limited to low-to-moderate service temperatures below 70 °C continuous because high VA content and plasticizer-free formulation show softening at elevated temperatures.

Compounding lines that introduce aluminium hydroxide or magnesium hydroxide through a side feeder at a specific energy of 0.18–0.25 kWh/kg can use LG EVA 15006 as a partial carrier for halogen-free flame-retardant masterbatches. The polar vinyl acetate domains reduce filler agglomeration compared with linear low-density polyethylene, but the low melt index of 0.6 g/10 min means that a 40:1 L/D co-rotating twin-screw extruder with screw speeds of 250–400 rpm is required to achieve acceptable dispersion without exceeding melt temperatures of 200 °C. Gravimetric feeding accuracy is maintained within ±0.5 wt% for the resin, and the filler is introduced in at least two injection ports to reduce torque peaks. Masterbatch letdown ratios in downstream cable compounds typically range from 3 wt% to 8 wt%, depending on the limiting oxygen index target. The final compound is subjected to a filter pressure test according to EN 13900-5, and unacceptable batches show a pressure rise greater than 0.5 bar/min during the first 20 min of extrusion. Production failure modes include screw wear at the first kneading block after filler injection, condensed moisture bridging in the hopper when relative humidity exceeds 60%, and batch-to-batch melt flow index shifts when the EVA content is not kept within ±2 wt%. Heavy-metal limits are verified under RoHS 2011/65/EU as amended by (EU) 2015/863, and a REACH SVHC declaration must be obtained from the compounder. Published data for this specific grade as the sole carrier in highly filled halogen-free masterbatch is limited, and most converted formulas replace up to half of the low-MFR EVA with a high-MFR EVA or metallocene LLDPE to balance wetting and throughput.

Injection Molded Technical Parts Requiring High Clamp Force

Injection molding of EVA 15006 differs from general-purpose LDPE because the high melt viscosity prevents filling of thin-walled sections below 1.5 mm at moderate injection pressures. A single-stage reciprocating screw with an L/D of 18:1–20:1 and a compression ratio of 2.0:1 is used, and the shot size is normally limited to 60–70% of the barrel capacity to avoid prolonged residence time and thermal degradation. Barrel temperatures from the feed throat to the nozzle are set at 150–170 °C, 165–180 °C, and 175–190 °C, while the mold is cooled to 20–40 °C because semi-crystalline EVA requires rapid setting. Injection speed is increased until the melt front reaches the last cavity without jetting, and holding pressure is typically 60–80% of the peak injection pressure. Clamp force is calculated from projected part area and cavity pressure; a cavity pressure of 400–600 bar with a projected area of 100 cm² corresponds to approximately 40–60 tonnes of clamp force, which explains why hot-runner tools with multiple cavities may require press capacities above 200 tonnes for this grade. Gate thickness for tab and fan gates should not be below 1.5 mm because shear heating can cause burn marks on the gate vestige. Molded parts are conditioned at 23 ± 2 °C and 50 ± 5% relative humidity for at least 40 h before tensile testing under ISO 527-2, flexural testing under ISO 178, and Shore D hardness testing under ISO 868. The grade is suitable for semi-rigid gaskets, secondary closures, sports equipment handles, and soft-touch inserts where a Shore D value near 40–45 is required without plasticizer. The primary injection molding defects are jetting when the gate size is too small, weld-line brittleness when the melt flow index is too low for multi-gate tools, and sink marks when packing time is shortened below the gate freeze-off time. Materials requiring food-contact or toy safety compliance must be verified for specific migration under EU 10/2011 or heavy-element limits under EN 71-3; no blanket compliance is assumed.

Wire and Cable Jacketing Compounds With EVA as a Melt-Processable Modifier

When EVA 15006 is blended with LDPE and EPDM in wire and cable jacketing compounds, the 15 wt% vinyl acetate content improves filler wetting and low-temperature flexibility, while the low melt flow index contributes to melt strength during tube-down extrusion. Compounders run the blend on a twin-screw extruder with an L/D of 24:1 to 28:1 and a cable crosshead die; the melt temperature at the die is limited to 180–200 °C to protect the peroxide or silane cure package. For halogen-free flame-retardant jacket compounds, aluminium hydroxide loadings of 60–70 wt% are typical, and EVA 15006 replaces a portion of the LDPE phase to improve elongation retention after aging at 100 °C for 168 h under IEC 60811-1-1. Flame retardance is assessed by IEC 60332-1-1 single-wire flame propagation, and cold bending is verified at −25 °C according to cable standard test methods. The resin is pre-dried to below 0.05 wt% moisture before compounding because residual water reacts with mineral flame retardants and increases void content in the jacket. Production failure modes on jacketing lines include die drool at the crosshead when the melt temperature exceeds 200 °C, surface roughness from insufficient dispersion of the mineral filler, and conductor adhesion loss when the insulation shield is not preheated to 70–80 °C before jacket application. Published data for EVA 15006 as the sole base polymer in jacketing is limited; industrial experience supports its use as a modifier at 10–30 phr within a blended matrix rather than as the main wire insulation resin, due to the low melt flow index and the associated screw torque demands at high filler loadings.