Copolímero de acetato de vinilo de etileno ELVAX 3174

In hot-melt adhesive compounding, ELVAX 3174 is introduced as a high-molecular-weight ethylene-vinyl acetate copolymer with a vinyl acetate content of 18 wt% and a nominal melt index of 8.0 g/10 min at 190 °C under 2.16 kg load per ISO 1133-1:2022. The neat copolymer has a density of 0.94 g/cm³ per ASTM D792 and a Vicat softening temperature near 75 °C per ASTM D1525. In packaging lines, the grade is dry-blended with hydrogenated rosin ester tackifier and a paraffin/naphthenic wax in ratios of 30–35 phr EVA, 30–40 phr tackifier, and 25–35 phr wax; the resulting Brookfield viscosity at 177 °C is targeted at 1,200–2,500 mPa·s per ASTM D3236. Viscosity stability during slot-die application is monitored with a Thermosel rotational viscometer, and set-time on corrugated board is measured by the time to fiber-tear bond under ASTM D1876 T-peel at 23 °C and 50% RH. The 18 wt% vinyl acetate content increases polar interaction with clay-coated and recycled board surfaces, while the 8.0 g/10 min melt index provides lower stringing than 400-MI grades at the same nozzle temperature of 165–175 °C. Open time is governed by the wax crystallisation onset measured by differential scanning calorimetry per ASTM D3418; a wax crystallisation onset of 60–70 °C is typical when a fully refined paraffin wax with melting point 58–62 °C is used. Adhesive shear adhesion fail temperature is evaluated per ASTM D4498; typical packaging formulations with this resin show cohesive failure above 60 °C when storage is below 40 °C. Thermal exposure above 200 °C for more than 8 h accelerates acetic acid evolution and gel formation, so pre-melt reservoirs are blanketed with nitrogen and held at 165 °C when line downtime exceeds 30 min. Pre-drying is not required if moisture content is below 0.05 wt%; at relative humidity above 60%, vacuum drying at 60 °C for 4 h is applied before compounding. Where indirect food-contact status is specified, the base resin is referenced under 21 CFR 177.1350 for ethylene-vinyl acetate copolymers; finished adhesive migration must satisfy the overall migration limit of 10 mg/dm² under EU Regulation 10/2011. Published formulation data for this exact grade in finished hot-melt adhesives is limited; the quoted ratios and viscosity window are process targets for EVA/tackifier/wax systems with 18 wt% VA and melt index near 8.0 g/10 min.

What Changes When an 8-MI, 18% VA Resin Modifies Paraffin Board Coatings?

Modification of paraffin board coatings with ELVAX 3174 at 10–20 wt% changes the wax crystal network from large brittle plates to smaller interlocked domains. The copolymer is melt-blended into paraffin wax with a drop melting point of 56–64 °C; needle penetration measured per ASTM D1321 at 25 °C typically drops from 15–20 dmm for unmodified paraffin to 8–12 dmm at 15 wt% addition. Kinematic viscosity at 100 °C, measured per ASTM D445, increases from 4–6 mm²/s to 12–18 mm²/s, which reduces strike-through during curtain coating onto 200–300 g/m² linerboard. Low-temperature flexibility is assessed by a 15-mm mandrel bend at 5 °C per ASTM D522; EVA-modified wax shows edge cracking only below 0 °C, whereas unmodified paraffin fails at 8–10 °C. Mixing is performed in a jacketed high-shear kettle at 110–130 °C under nitrogen for 45–60 min; batch-to-batch variation in EVA dispersion is held below ±2 °C cloud point. Addition above 20 wt% may cause non-uniform gloss and uneven coating weight due to phase separation, particularly with straight-chain paraffin grades having oil content above 0.5 wt%. Published data for this specific resin in wax-based anti-slip coatings remains limited, but the compatibility behaviour follows the standard EVA-wax blend model for 18 wt% VA copolymers.

Compounding Carrier Resins and Polyethylene Toughness Modification

For carbon black and pigment masterbatch production, ELVAX 3174 functions as a polar carrier because the 18 wt% vinyl acetate reduces crystallinity and improves wetting of untreated carbon black at loadings of 40–50 wt%. Compounding is carried out on a co-rotating twin-screw extruder with an L/D ratio of 44:1 and a screw speed of 300–600 min⁻¹; melt temperature at the die is maintained at 180–220 °C and checked with an infrared probe calibrated against melt flow index per ISO 1133-1:2022. Filter pressure value is evaluated on a 25-mm single-screw extruder with a screen pack of 200/400/200 mesh; pressure rise limits of 0.5 bar/min are used to detect undispersed agglomerates. In polyethylene modification, blending 5–15 wt% ELVAX 3174 into LLDPE raises dart impact strength per ASTM D1709A from 120–150 g to 180–250 g, while environmental stress-crack resistance F50 per ASTM D1693 in 10% Igepal at 50 °C exceeds 1,000 h for the modified material. The blend retains a melt flow ratio suitable for blown film extrusion on a 30:1 L/D extruder; die gap is set at 1.8–2.2 mm to control melt fracture. Published data for this exact EVA grade in high-filler masterbatches is limited, but the carrier-resin mechanism is established for EVA copolymers with 18 wt% VA.

Closed-cell midsole compounds incorporating ELVAX 3174 are prepared in a tangential Banbury internal mixer at 100–120 °C with dicumyl peroxide at 0.8–1.2 phr and azodicarbonamide at 2.5–5.0 phr. Zinc oxide at 3–5 phr and stearic acid at 1–2 phr are added as kicker and dispersing aids; the dump temperature is kept below 120 °C to prevent premature decomposition of the blowing agent. The higher molecular weight of this 8.0 g/10 min grade compared with 150-MI EVA improves melt strength during foam expansion, reducing cell coalescence at the expansion stage. Press molding is conducted at 170 °C under 8–12 MPa for 8–10 min; the demolded slab is cooled under pressure to stabilize cell size. Foam density is measured per ASTM D792 after conditioning at 23 °C for 24 h; typical midsoles fall in the range of 0.10–0.20 g/cm³. Hardness is measured with an Asker C durometer on a 10-mm thick skinless specimen after 15 s; values of 45–55 Asker C are common for this compound class. Residual azodicarbonamide above 0.3 wt%, measured by thermogravimetric analysis at 200 °C, causes surface pitting and must be reduced through adequate mold venting of 0.5–1.0 mm channels. Published data for this exact grade in compression-molded midsole foam is limited; the processing window is derived from EVA foam compounds with similar VA content and melt index.

When Flame-Retardant Cable Jacket Compounds Shift to High-Filler Low-Smoke Formulations

Loaded with 60–65 wt% aluminium trihydroxide, ELVAX 3174 compounds are produced on a co-rotating twin-screw extruder with 44:1 L/D; filler is side-fed after polymer melting at 160–180 °C to prevent the mass temperature from exceeding 200 °C, at which point ATH begins releasing water. Compound melt flow index is measured per ISO 1133-1:2022 at 190 °C under 2.16 kg; values of 2–5 g/10 min are retained for pressure extrusion through a 90-mm single-screw crosshead line. Tensile strength and elongation at break are tested per IEC 60811-501 /ISO 527-2; the compound typically reaches 10–14 MPa and 150–250%, respectively, before ageing. Oxygen index measured per ISO 4589-2 on 3-mm plaques exceeds 30–35% O₂ at 60–65 wt% ATH. Smoke density per IEC 61034-2 on 1-mm cable specimens is below 2.5 light absorbance. The compound requires zinc stearate at 1–2 phr as an acid scavenger; amine-based flame-retardant synergists are avoided because they promote premature acid-catalysed chain scission. Published data for this specific EVA grade in LSZH jackets is limited, but the performance envelope aligns with EVA copolymers having 18 wt% VA and melt index below 10 g/10 min.

At 3–7 wt% addition, ELVAX 3174 modifies 60/70 penetration-grade bitumen for roofing membranes and asphalt concrete. High-shear mixing at 180–190 °C for 90–120 min disperses the copolymer phase; softening point per ASTM D36 increases from 45–52 °C to 65–75 °C, while penetration at 25 °C per ASTM D5 decreases from 60–70 dmm to 30–45 dmm. Brookfield viscosity at 135 °C per ASTM D4402 remains within 1.0–2.5 Pa·s, allowing pumping through heated lines to the membrane line. Low-temperature flexibility is checked on a 10-mm mandrel at −10 °C per ASTM D5147; modified binders show surface cracking only below −15 °C in laboratory formulations. Storage stability is evaluated by the difference in softening point between top and bottom after 72 h at 163 °C; phase separation above 2 °C indicates insufficient mixing or unsuitable asphalt chemistry. The addition level is limited to 7 wt% because higher concentrations raise mixing torque beyond 200 N·m and reduce workability. Published data for this specific resin in polymer-modified asphalt remains limited, but the performance shift follows general EVA-bitumen modification practice.