Copolímero de acetato de vinilo de etileno HANWHA EVA 2020

Introduced by Hanwha Solutions as part of its ethylene-vinyl acetate copolymer product line, HANWHA EVA 2020 Ethylene Vinyl Acetate Copolymer is a random copolymer with a nominal vinyl acetate content of 20 wt% and a melt index of 2.0 g/10 min determined at 190 °C under a 2.16 kg load in accordance with ASTM D1238. The resin is supplied in pellet form and is identified under CAS Registry Number 24937-78-8. Typical density is 0.940 g/cm³ by ASTM D1505. The molecular architecture contains random acetate side groups distributed along an ethylene backbone, reducing crystallinity relative to low-density polyethylene while retaining sufficient melt strength for injection molding and profile extrusion. The numerical designation is typically read as corresponding to the nominal 20 wt% vinyl acetate content and a 2.0 g/10 min melt index, although lot-specific values are controlled by certificate of analysis.

The grade is specified for applications requiring a balance of adhesion, flexibility, and processability. Unlike lower-VA grades, EVA 2020 provides higher polar surface adhesion and improved low-temperature flexibility. Unlike higher-VA grades, it retains higher hardness, higher tensile strength, and better heat resistance. These differences are exploited in hot-melt adhesives, crosslinked footwear foam, injection molded footwear components, wire and cable compounds, and polymer modification. The following sections provide the property window, processing limits, and comparative selection data.

Material profile and certified property window

These values are typical ranges, not batch-certifying limits. Lot-specific certificates of analysis control moisture content, melt flow rate, vinyl acetate content, and additive package. Users should verify each specification against the purchase specification because additive formulations vary by grade and intended market.

Hot-melt adhesive compounding has been a primary application for 20 wt% VA EVA grades. In a typical high-tack packaging adhesive, EVA 2020 is melt-blended with 25–40 wt% rosin ester tackifier, 5–15 wt% Fischer-Tropsch wax, and 0.2–0.5 wt% antioxidant at 150–180 °C in a jacketed mixer. The polar acetate groups promote wetting of paper, board, wood, and polar plastic surfaces, while the ethylene segments maintain cohesive strength and heat resistance. In hot-melt systems, tackifier migration kinetics are affected by polar vinyl acetate content: 20 wt% VA increases tackifier compatibility relative to LDPE but does not produce the excessive plasticization observed with 28–33 wt% VA grades. Formulation adjustments are evaluated by heat-fail temperature under ASTM D4498 and by peel resistance under ASTM D1876. Because the melt index is 2.0 g/10 min, the formulation retains medium viscosity; high-speed sprayable recipes often dilute the resin with wax or switch to a higher melt index grade.

Crosslinked foam compounding is another volume application. EVA 2020 is milled at 100–120 °C with 2–5 phr azodicarbonamide, 0.5–1.2 phr dicumyl peroxide, 1–2 phr zinc oxide, and stearic acid. The sheet is then expanded in a press at 160–175 °C. The 20 wt% vinyl acetate content reduces crystallinity and allows uniform cell nucleation; however, if peroxide and blowing agent decomposition are not balanced, gas loss and foam collapse occur. Higher-VA grades produce softer foam, while lower-VA grades require higher blowing agent loadings to achieve comparable expansion at the same crosslink density.

Why does 20 wt% vinyl acetate alter thermal and rheological response?

The random incorporation of 20 wt% vinyl acetate reduces crystalline content from roughly 40–55% for low-density polyethylene to approximately 10–20%. This lowers the peak melting temperature to 82–86 °C and reduces Vicat softening to 58–62 °C. The amorphous regions increase segmental mobility, which improves low-temperature impact and environmental stress crack resistance under ASTM D1693 when compared with LDPE. However, the same structural change reduces tensile modulus and hardness and lowers the continuous-use temperature under load to approximately 60–70 °C.

Rheologically, EVA 2020 is a shear-thinning melt with a melt index of 2.0 g/10 min. At low shear, the melt has enough viscosity to retain shape during profile extrusion; at higher shear, apparent viscosity drops, allowing injection filling of thin sections. Melt strength is lower than high-pressure LDPE of similar melt index because the shorter ethylene sequences reduce entanglement density. This is measurable as reduced melt tension on a Göttfert Rheotens unit at 190 °C and limits drawdown ratios in sheet or film extrusion. In processing, this requires lower drawdown ratios and may require air cooling at the die to prevent sagging.

In production-scale co-rotating twin-screw compounding on a 40:1 L/D extruder, EVA 2020 is usually starve-fed with barrel set points from 130 °C at the feed throat to 170–180 °C in the mixing zones and 160–170 °C at the die. Screw speed is commonly 200–300 rpm, but specific energy input should remain below 0.18–0.22 kWh/kg to prevent local overheating. Feed-throat cooling is required because pellets soften above 60 °C and can bridge. If ambient relative humidity exceeds 60%, pre-drying at 60–70 °C for 4 h in a desiccant dryer prevents splay and surface defects. The resin can be processed on single-screw extruders with 24:1–30:1 L/D and 2.5:1–3.0:1 compression ratio, using a Maddock mixing section for homogenization. For injection molding, melt temperatures of 170–200 °C and mold temperatures of 20–40 °C are typical; packing pressure is lower than semicrystalline polypropylene of similar melt index.

When EVA 2020 replaces a lower-VA grade in extrusion and injection molding

Moving from a 15 wt% VA grade with equivalent melt index to EVA 2020 reduces hardness by approximately 5–8 Shore A points, reduces tensile strength by roughly 20–30%, and lowers Vicat softening by 5–8 °C, while increasing elongation at break and low-temperature flexibility. The melt-processing temperature can be reduced by 5–10 °C. Molds with high packing requirements may need lower packing pressure, and profile extrusion die settings may require a slight opening to compensate for reduced melt viscosity. The table below summarizes directional property changes relative to adjacent vinyl acetate contents at equivalent melt index.

Relative to a higher-VA grade at equivalent melt index, EVA 2020 has higher hardness, higher tensile strength, and better heat resistance but lower elongation, lower clarity, and reduced adhesion to highly polar surfaces. The choice between grades is therefore governed by whether adhesion and softness or stiffness and heat resistance control the end-use requirement. Published data for this specific configuration is limited to the directional ranges above, so pilot-scale confirmation is required before replacing a qualified grade.

Operational limits, pre-drying, and additive incompatibilities

Thermal degradation by deacetylation is the primary processing constraint. At temperatures above 230 °C, acetic acid is liberated, causing yellowing, melt index drift, and corrosion of unprotected barrel surfaces. The practical upper melt-temperature limit is 210 °C, and residence time at temperature should be minimized. Equipment exposed to EVA 2020 should use nitrided or bimetallic barrels and stainless-steel downstream tooling where possible. The acetate group also undergoes hydrolysis when exposed to strong mineral acids or strong bases, especially above ambient temperature. Ketones, esters, and aromatic hydrocarbons such as methyl ethyl ketone and toluene swell or dissolve EVA 2020; contact should be avoided unless solvent bonding is explicitly intended. Amine-containing processing aids should be evaluated by accelerated aging because residual acetic acid from low-level deacetylation can reduce their long-term stability.

Regulatory status is lot-specific. Hanwha Solutions generally maintains REACH registration for EVA products placed on the EU market. RoHS Directive 2011/65/EU restrictions for lead, mercury, cadmium, hexavalent chromium, PBB, and PBDE are not intentionally added; compliance is confirmed by supplier declaration. For food-contact use, EVA 2020 is typically formulated to meet FDA 21 CFR 177.1350 when used in accordance with the regulation’s end-use limitations, but the specific certificate of compliance must be obtained for the purchased lot because additive packages vary. Medical-grade applications require additional ISO 10993 testing and are not implied by resin grade alone.

In peroxide-cured wire and cable insulation, EVA 2020 is selected for filler acceptance with aluminum trihydrate and magnesium hydroxide at loadings up to 150 phr. Cure behavior is monitored by moving-die rheometer per ISO 6502, with scorch time and torque reflecting vulcanization kinetics. The 20 wt% VA content provides better filler wetting than lower-VA grades and better heat resistance than higher-VA grades, making it a midpoint candidate for low-smoke halogen-free compounds. Published data for this specific configuration is limited, so compound development should include long-term oven aging per IEC 60811-401 to confirm retention of tensile elongation after thermal exposure.