ELVAX 3169Z Ethylene Vinyl Acetate Copolymer

Unsupported foil-lamination sealant layers in retort-capable flexible packaging process ELVAX 3169Z at nominal melt temperatures between 210 °C and 230 °C on a 90 mm single-screw extruder configured with a 30:1 L/D barrier screw and a coat-hanger die. The 18 wt% vinyl acetate content places the copolymer below the 20–28 wt% range required for very low-temperature hot-tack, yet the grade forms a sealant skin against aluminium foil and corona-treated PET when an acid- or solvent-based primer is applied. Line speeds are typically set between 80 m/min and 180 m/min. Coat weight is controlled between 12 g/m² and 25 g/m²; below 12 g/m², pinhole formation increases at speeds above 150 m/min, while above 25 g/m² the sealing layer can tear along die-cut score lines during package opening. Neck-in measured on a 1 m coat-hanger die is reduced by maintaining an air gap below 200 mm and a chill-roll temperature of 15–20 °C. A melt temperature above 235 °C increases gel and odour from acetate side-group degradation; below 205 °C, melt draw becomes unstable and edge weave increases. Adhesion is evaluated by T-peel according to ASTM D1876-15e1. Values below 2.5 N/15 mm indicate insufficient oxidation or primer coverage on the foil surface, whereas values above 5.0 N/15 mm often coincide with odour and seal-through contamination from an over-oxidized melt film. Pre-drying the resin at 60 °C for 2 h is used when ambient relative humidity exceeds 60 % to reduce moisture-related bubble defects.

Under What Conditions Does the Dicumyl Peroxide Cure Curve Outrun Azodicarbonamide Gas Yield?

In expanded footwear midsole and industrial gasket foaming, ELVAX 3169Z is compounded in a 75 L tangential internal mixer at 95–110 °C with 100 phr base resin, 2.0–4.0 phr azodicarbonamide, 0.6–1.2 phr dicumyl peroxide, 0.5–1.5 phr zinc oxide, and 0.3–0.8 phr zinc stearate. Rotor speed is maintained at 30–40 rpm, and ram pressure is held at 5–6 bar until flux is achieved. The processing conflict is kinetic. Dicumyl peroxide reaches its 1 h half-life at approximately 137 °C and its 1 min half-life near 171 °C, while untreated azodicarbonamide gas release begins only near 195–210 °C. If the cure exotherm accelerates before enough gas has formed, cell walls tear and sheet density remains above 0.25 g/cm³. If gas evolves before sufficient gelation, the foam collapses below 0.12 g/cm³ and gel fraction measured by ASTM D2765-16 falls below 55 wt%. Zinc oxide is added as a kicker to pull blowing-agent decomposition onset closer to 160–170 °C, aligning gas yield with the peroxide cure curve. In a 500 mm × 500 mm compression press, the pre-mixed sheet is cured at 178 °C for 6–8 min under 150 kg/cm². Foam density tested according to ISO 845 typically falls between 0.14 g/cm³ and 0.20 g/cm³. A processing window of ±5 °C around the 178 °C setpoint is observed on production lines. Lower plate temperature produces grey streaks of unconverted azodicarbonamide; higher plate temperature triggers peroxide scorch at the sheet surface. Batch-to-batch variance in azodicarbonamide particle size can shift density by ±0.015 g/cm³ even when the cure time is unchanged. Pre-drying the compound at 60 °C for 2 h is required when ambient relative humidity exceeds 60 % to prevent steam-induced cells from disturbing the density gradient. Amine-based antioxidants should not be introduced in this recipe because they react with the peroxide decomposition pathway and can increase gel fraction unpredictably before the blowing agent has fully expanded.

Hot-melt adhesive compounding for carton-closing and bookbinding uses ELVAX 3169Z at 25–40 wt% as the thermoplastic base polymer rather than as the primary low-temperature bonding resin. The 18 wt% vinyl acetate content and 1.5 dg/min melt index measured at 190 °C/2.16 kg according to ASTM D1238-20 produce higher cohesive strength and longer open time than a 28 wt% VA, 400 dg/min hot-melt grade, but the polar tack contribution is lower. The blend is compounded in a heated 50 L sigma-blade mixer at 160–180 °C with a C5 aliphatic hydrocarbon tackifier at 35–50 wt%, paraffin wax at 10–20 wt%, and hindered phenolic antioxidant at 0.3–0.5 wt%. Mixing is continued for 45–90 min after full melt-out to reduce tackifier-rich droplets. Brookfield viscosity measured at 180 °C with a Thermosel spindle remains between 2,000 mPa·s and 8,000 mPa·s, depending on wax chain length. Softening point by ASTM E28 is maintained between 85 °C and 105 °C. At tackifier addition above 50 wt%, the mixture tends to become hazy and phase-separate, which reduces peel on recycled corrugate below 2.0 N/cm under ASTM D1876. Published data for this specific ELVAX 3169Z/tackifier haze point is limited, so pilot trials are required when changing tackifier aromaticity or wax molecular weight. Processing above 190 °C for more than 4 h initiates vinyl acetate deacetylation and darkening. The tank is blanketed with nitrogen if hold time exceeds 2 h.

When ATH and Magnesium Hydroxide Loadings Exceed 55 wt% in a Low-Melt-Index EVA Matrix

Once total aluminium hydroxide and magnesium dihydroxide loadings exceed 55 wt% on a low-melt-index EVA base, halogen-free flame-retardant sheathing compounds develop the required char yield but also impose tight extrusion control. On a 24:1 L/D single-screw wire-coating line with a barrier screw and 120 mm diameter, melt temperature must be kept below 170 °C because aluminium hydroxide begins endothermic dehydration near 190–200 °C. A thermal spike above 185 °C produces microvoids and a measurable drop in tensile strength. The low 1.5 dg/min melt index raises head pressure and screw torque compared with a 6 dg/min EVA grade. Barrel temperatures are set at 120–140 °C in the feed zone and 140–160 °C in the metering zone. Fillers are pre-dried at 80 °C for 4 h when relative humidity exceeds 60 % to avoid steam-porosity in the insulation wall. The compound includes 0.5–1.0 wt% vinylsilane or aminosilane coupling agent to control filler-matrix adhesion. An excess of zinc stearate above 1.0 wt% can reduce limiting oxygen index measured by ISO 4589-2. Tensile properties before ageing are tested according to IEC 60811-501; elongation at break should remain above 150 % after formulation optimization. Flame performance on single specimens is evaluated by IEC 60332-1-2, and acid gas emission is checked by IEC 60754-2. Amine-based antioxidant packages should be avoided when peroxide cure is not present, because residual amines can interfere with silane coupling agents and reduce filler wetting stability during long extrusion runs.

High-Shear Bitumen Integration and Separation Tendency in Paving-Grade Binders

Polymer-modified bitumen for road surfacing and waterproofing membranes incorporates ELVAX 3169Z at 4–7 wt% based on bitumen weight. Dispersion is performed in a high-shear rotor-stator mill at 180–190 °C for 60–120 min. Lower shear rates produce large polymer domains and storage instability. The low 1.5 dg/min melt index means the grade resists thermal degradation during paving-plant storage better than high-MI EVA, but it requires higher blend viscosity. Softening point measured by ASTM D36/D36M-14 rises from approximately 45–50 °C for the base bitumen to 65–80 °C after polymer addition. Penetration at 25 °C by ASTM D5 decreases, and elastic recovery by ASTM D6084 improves when the polymer network is properly elongated. Storage stability is evaluated by the difference in softening point between top and bottom samples after 72 h at 163 °C in a sealed tube. A difference greater than 5 °C indicates phase separation. If high-shear mixing is truncated before the EVA phase is fully dispersed, the compound can show surface skinning in the tank and a non-uniform polymer phase in the pavement mix. Published data for this specific ELVAX 3169Z asphalt stability index is limited; plant suitability therefore requires a full-scale trial at the target production temperature rather than reliance on laboratory blend curves.

In coextruded cast film for frozen food and liquid packaging, a sealant layer containing 70 wt% metallocene linear low-density polyethylene and 30 wt% ELVAX 3169Z is processed at 220–240 °C melt temperature on a 250 mm width three-layer cast line. The EVA component reduces seal initiation temperature by approximately 8–12 °C relative to a pure metallocene LLDPE layer when measured by ASTM F1921-15. Hot-tack strength is less responsive above 130 °C seal temperature because the 18 wt% vinyl acetate content provides less low-temperature polarity than a 28 wt% VA grade; this is an intentional selection criterion for films that must not seal through contaminated areas in high-speed vertical form-fill-seal machines. Screw speed and chill-roll temperature are controlled at 60–90 rpm and 18–22 °C. Higher chill-roll temperatures above 25 °C increase film haze measured by ASTM D1003 and can cause blocking at the reel. The sealant layer is typically extruded at 8–15 µm thickness within a 50–80 µm total film. Dart impact measured by ASTM D1709 is maintained above 500 g when the EVA fraction does not exceed 30 wt%. Above this threshold, film blocking at roll edges increases and unwind tension must be reduced.

As a low-melt-index modifier in extruded closure liners, ELVAX 3169Z is blended at 20–30 wt% with linear low-density polyethylene on a 45 mm single-screw extruder at 180–200 °C and tested for compression set according to ASTM D395-18; published data for this specific grade in cap-liner compounds is limited, so pilot-scale torque and seal-force trials are required.