Copolímero de acetato de vinilo de etileno EVAtech EVA 120S/12G

On blown film lines above 60% ambient relative humidity, EVA 120S/12G is pre-dried at 60°C for 4 h to keep surface moisture below 0.1%. The 12G segment of the designation identifies a 12% vinyl acetate comonomer fraction by mass. This comonomer disrupts polyethylene crystallinity and lowers seal initiation temperature when the resin is blended with a butene- or hexene-copolymer LLDPE. The base LLDPE is typically selected with density 0.918 g/cm³ and MFR 1.0 g/10 min at 190°C/2.16 kg. EVA 120S/12G is added at 10–30 wt%. A dry blend is fed to a single-screw extruder with barrier geometry and L/D of 30:1. The barrel profile from feed to die is 150°C, 165°C, 175°C, 185°C, and 190°C. Die gap is set at 1.8 mm. Blow-up ratio is controlled between 2.0:1 and 2.8:1. Frost line height is maintained at 300–450 mm to stabilize bubble geometry. Higher EVA addition lowers tensile modulus. Dart impact is verified by ASTM D1709. Seal strength is measured by ASTM F88. Typical film gauge is 40–80 µm. Food-contact film must comply with 21 CFR 177.1350(b) and Regulation (EU) No 10/2011. The converter must run total migration tests under the intended food simulant before commercial shipment. Terminal products include frozen food bags, bakery films, and collation shrink film.

Process deviations above 200°C release acetic acid from the vinyl acetate group. This causes corrosion on the screw, die lip, and air ring. The bubble develops specks and gel-like defects. Amine-based slip additives should not be pre-blended into the EVA-rich pellets because free acetic acid in the melt can deactivate the amine function and create salt residues on the die face. The extruder should be purged with LLDPE before shutdown. A shutdown longer than 30 min at melt temperature requires lowering the barrel profile to 140°C. Published data for EVA 120S/12G in coextruded high-barrier structures is limited. Commercial trials should include MFR verification per ISO 1133-1:2022 and DSC crystallinity per ISO 11357-3. The grade designation does not itself encode the melt flow rate under 190°C/2.16 kg; the mill certificate must be consulted before screw speed and throughput are fixed.

What Drawdown Limits Govern Extrusion Coating with 12% VA EVA?

Extrusion coating operations that replace part of the autoclave LDPE with EVA 120S/12G are constrained by drawdown, neck-in, and thermal stability. The grade is added at 15–40 wt% to the LDPE charge. The blend is fed to a single-screw extruder with 90 mm screw diameter and 32:1 L/D. Die width on production lines ranges from 1,800 mm to 2,600 mm. The die gap is set at 0.5–0.8 mm. The air gap is maintained at 150–250 mm. Line speed is limited by the onset of draw resonance. At melt temperatures above 290°C, acetic acid evolution accelerates. The melt temperature is therefore controlled at 260–280°C. Coating weight on paperboard is 15–25 g/m². The EVA component improves adhesion to polar substrates. Peel adhesion is measured per ASTM F88. Neck-in is typically reduced by 5–15% relative to pure LDPE, depending on die gap and air gap. For food-contact paperboard, the construction falls under 21 CFR 176.170(c). For laminating adhesive functions, 21 CFR 175.105 applies. Terminal structures are aseptic cartons, drinking cups, and multi-wall bags.

Production-scale observation shows that high-efficiency screw profiles designed for pure LDPE may over-shear EVA-rich blends. The preferred configuration is a low-compression screw with dispersion elements after the feed section. Barrel temperatures should not be ramped above 285°C near the die. The extruder head pressure is monitored continuously; a pressure rise above the established baseline signals gel accumulation at the die lip. If the line is stopped for more than 20 min, the die must be purged with LDPE before restart. The coating line must not run with a colder die below 250°C, because the higher melt elasticity of the EVA component produces edge weave and uneven coat weight. The exact drawdown ceiling must be established by a line trial because published data for this specific EVA grade in high-speed extrusion coating is limited.

In hot-melt adhesive compounding, EVA 120S/12G is mixed under a nitrogen blanket in a sigma-blade mixer or a co-rotating twin-screw extruder with melt recirculation. The lower vinyl acetate content reduces polar surface interaction compared with EVA grades containing 25–28% VA. The formulator compensates by raising tackifier concentration. A packaging-grade formulation contains 25–35 wt% EVA 120S/12G, 35–45 wt% C9 aromatic-modified tackifier, 20–30 wt% microcrystalline wax, and 0.3–0.8 wt% hindered phenolic antioxidant. The mixing vessel is held at 150–165°C. Blade or screw speed is adjusted to keep shear heating below 180°C. Brookfield viscosity at 180°C is measured per ASTM D3236. Target viscosity depends on application equipment: wheel applicators require 800–1,500 mPa·s, nozzle systems 1,500–2,500 mPa·s. Open time is set by the wax melting point and the EVA concentration. For carton sealing under 21 CFR 175.105, the assembled package must be tested for migration. Short-cycle compression bonding requires fast set-back. The vinyl acetate distribution, if confirmed by FTIR per ASTM D5594, determines batch-to-batch melt stability. Terminal uses include case sealing, bookbinding, and label attachment.

The mixer must not exceed 180°C because the EVA backbone begins thermal scission and the tackifier may undergo color-body formation. A temperature overrun is corrected by reducing rotor speed and adding a small mass of cool wax. In-line filtration with a 60–100 mesh screen pack removes char particles. The completed adhesive is discharged onto a cooled belt and slit into blocks or pellets. Storage must be below 35°C and away from direct sunlight to prevent blocking. Formulators must avoid amine-based adhesion promoters in the same melt because the acidic residues from EVAc processing can form amine salts and reduce tack. Published data for EVA 120S/12G in high-speed case sealing is limited to general EVA-based HMA studies.

LSZH Cable Jacketing Compounds Tested under IEC 60332-3-24

Mineral-filled halogen-free compounds use EVA 120S/12G as a partial replacement for LLDPE or as the main polar base resin. The vinyl acetate group increases filler acceptance. A jacketing formulation contains EVA 120S/12G 60–80 wt%, LLDPE 20–40 wt%, aluminum trihydrate 120–180 phr, magnesium dihydrate 20–40 phr, vinyl silane coupling agent 0.5–1.5 phr, and antioxidant 0.3–0.8 phr. The compound is processed in an internal mixer with a drop temperature of 140–155°C, then pelletized by a single-screw extruder with a screen pack of 80–120 mesh. A co-rotating twin-screw extruder with L/D 40:1 and temperature profile 110–160°C may also be used. The screw and barrel must be corrosion-resistant. Acetic acid released at high temperature can attack standard nitrided steel. The finished cable jacket is tested for flame spread per IEC 60332-3-24 and for halogen acid gas content per IEC 60754-1. Tensile strength and elongation at break are measured per ASTM D638. The limiting oxygen index is typically in the 35–42% range for this filler level, but exact values require laboratory confirmation. The compound is not suitable for oil-resistant applications unless additional polar modifiers are incorporated. Terminal parts are building riser cables, railway rolling-stock cables, and marine cables.

Filler dispersion is the dominant processing risk. A two-stage mixing protocol is used when the filler loading exceeds 140 phr. The first stage mixes EVA 120S/12G, coupling agent, and two-thirds of the mineral filler at 120°C for 4 min. The second stage adds the remaining filler and the antioxidant at 135°C until the torque curve stabilizes. Single-stage mixing at high filler loadings produces agglomerates that lower elongation at break and increase jacket surface roughness. The compounder must log drop temperature, rotor speed, and ram position for every batch. Batch-to-batch variance in acetic acid release occurs when the feedstock has absorbed moisture above 0.08%. The resin must be dried at 60°C for 4 h under dew-point control before mixing if the storage bag is exposed to high humidity.

For color masterbatch production, EVA 120S/12G is processed on a co-rotating twin-screw extruder with L/D of 40:1 to 44:1. The formulation contains 40–60 wt% pigment, 30–50 wt% carrier resin, and 1–5 wt% polyethylene wax. The polar vinyl acetate groups improve pigment wetting. The extruder profile starts at 120°C, rises to 180°C, and falls to 150°C at the die. Screw speed is set between 300 rpm and 500 rpm. A dispersive mixing section with two kneading blocks is required before the vacuum vent. The vacuum vent must be connected to a trap because EVA volatiles contain acetic acid. The carrier should be pre-dried at 60°C for 4 h if moisture exceeds 0.1%. The final masterbatch is let down at 3–5 wt% into LDPE or LLDPE. Dispersion is verified by filter pressure test per EN 13900-5 or the equivalent internal method. The carrier MFR, measured per ISO 1133-1:2022, should be within ±30% of the letdown resin MFR to prevent melt flow separation. Terminal products include colored films, injection-molded closures, and pipe coatings.

Production lines operating above 500 rpm can generate acetic acid and lower carrier molecular weight if the screw has inadequate cooling capacity. The preferred configuration uses length-diameter ratios of 44:1 with an atmospheric vent before the vacuum vent. The first vent removes trapped air and moisture; the second vent removes residual volatiles. Pigment agglomerates larger than 20 µm create filter pressure failure. The operator must log filter pressure every 30 min during the run. A rising filter pressure curve indicates a change in pigment particle size or inadequate kneading intensity. Scrap from start-up is not re-fed into the same production lot because the acetic acid residues alter the coloristic values.

Azodicarbonamide gas yield defines the foaming window.

Crosslinked EVA foam using EVA 120S/12G requires blending with an EVA grade of higher vinyl acetate content. A mixture of 50–70 phr EVA 120S/12G and 30–50 phr EVA with 18–28% VA is common. The blowing agent azodicarbonamide is added at 1.5–3.5 phr. Dicumyl peroxide is added at 0.6–1.0 phr. Zinc oxide at 1.0–2.0 phr and zinc stearate at 0.5–1.0 phr control decomposition kinetics. The compound is mixed on a two-roll mill with front roll temperature 100–110°C and rear roll 90–100°C. The sheet is then compression molded at 160–175°C under 15 MPa. The gas yield of azodicarbonamide is 220 mL/g, but escape before crosslinking reduces foam density. The peroxide must reach 90% decomposition at the molding temperature to form the cell wall network. The foamed part is cooled under pressure to prevent collapse. Post-curing at 70°C for 2 h reduces residual peroxide by-products. The foam is tested for density per ISO 845 and compression set per ISO 1856. The 12% VA content of EVA 120S/12G produces a harder foam than high-VA grades. Terminal parts are sandal midsoles, exercise mats, and packaging inserts.

The processing window is narrow because the gas release temperature and the peroxide cure kinetics must overlap. A fast-curing peroxide will crosslink the matrix before the blowing agent decomposes, yielding closed cells with high density. A slow-curing peroxide will allow gas to escape before the melt strength increases, yielding collapsed cells and surface pinholes. The operator records the molding pressure curve during the cycle. A pressure drop earlier than the expected decomposition peak indicates premature gas escape. The mill gap is set at 2.0–3.0 mm for uniform additive dispersion. The compound sheet must be cooled below 40°C before stacking to avoid heat histories that change the decomposition behavior.

When 120S/12G Is Added to Oxidized Bitumen for Polymer-Modified Asphalt

In high-shear asphalt modification, EVA 120S/12G is dosed at 3–7 wt% of the bitumen mass. The mixer is held at 175–185°C. Mixing speed is maintained between 3,000 rpm and 5,000 rpm for 60–120 min. The EVA backbone is incompatible with asphaltenes at rest. Storage stability therefore requires a continuous agitation tank or an added compatibilizer. The modified binder is tested for softening point per ASTM D36, penetration per ASTM D5, and elastic recovery per ASTM D6084. A polymer network raises softening point and reduces penetration at 25°C. The exact values depend on the base bitumen. Published data for EVA 120S/12G in porous asphalt is limited. The binder must comply with EN 14023 when used under European road specifications. The compound is not recommended for low-temperature paving below -10°C unless a plasticizer is added. Terminal applications are bridge deck waterproofing, high-rut-resistance asphalt, and bituminous membranes.

Phase separation is the critical failure mode. A stored tank without agitation shows a polymer-enriched skin and an asphaltene-rich bottom layer within 24–48 h. The plant must sample the top and bottom of the storage tank and compare softening points. A difference greater than 5°C requires re-circulation or a reduction in storage time. The high-shear mixer must be equipped with a temperature control system that prevents hot spots above 190°C. EVA degradation at hot spots generates black specks and reduces the polymer modification efficiency. The mixer shaft should be inspected for bitumen coking every production campaign. The dosing rate must not exceed the mixing capacity because undispersed pellets form weak points in the final asphalt film.