Elevar EF206 EVA Copolymer Resin, 20% VA, 6 MI, Grau de embalagem de carne e aves de capoeira

Elevate EF206 is specified as an ethylene-vinyl acetate copolymer resin with 20 wt% vinyl acetate comonomer content and a nominal melt index of 6 g/10 min determined at 190 °C under a 2.16 kg load using ISO 1133-1:2022 or ASTM D1238. The grade is positioned for meat and poultry packaging sealant layers, particularly coextruded lidding films, vacuum skin packaging top webs, and form-fill-seal films requiring low heat-seal initiation and cold-temperature flexibility. Published proprietary data for this exact commercial configuration are limited; the performance envelope discussed below is therefore based on the established behaviour of 20% VA, 6 MI EVA copolymers and on standardised test methods rather than a supplier-specific datasheet.

The 20% vinyl acetate content places EF206 between low-VA grades with higher polyethylene crystallinity and high-VA grades used for cling and low-temperature seal applications. At this composition, the reduction in crystallinity relative to 9–18% VA EVA lowers the seal initiation range while retaining enough surface hardness to limit blocking in wound rolls. The 6 MI flow class places the resin in the cast film and extrusion coating range rather than in the high-molecular-weight blown film range. In coextruded barrier films, the core layer carries mechanical and barrier functions, so the EVA skin can be minimised to 10–25 µm to control extractables and blocking while retaining seal integrity.

What Limits the Processing Window for a 20% VA, 6 MI Sealant Resin?

On cast film and coextrusion coating lines used for meat lidding structures, EF206 is normally processed as an outer sealant skin of 10–25 µm within a total film thickness of 50–80 µm. The resin is fed into a 30:1 L/D single-screw extruder with a barrier screw and Maddock mixer, with feed-throat cooling engaged to prevent pellet softening and bridging. Rear zones are maintained at 120–150 °C, mid-barrel zones at 170–190 °C, and front zones plus adapter at 190–210 °C. Melt temperature measured at the die lip is typically kept at 195–215 °C. Prolonged residence above 230 °C accelerates deacetylation of the vinyl acetate comonomer, yielding acetic acid, gel specks, and odour. In production, die-lip buildup and chill-roll plate-out are the main failure modes when melt temperature exceeds 220 °C for extended runs; the resulting deposits transfer to the film surface and reduce seal consistency.

The screw should have a low compression ratio of 2.5:1 to 3.0:1 and a smooth feed section because the pellets soften at lower feed-throat temperatures than LDPE. Excessive shear heating from high-compression screws can push melt temperature above the 220 °C threshold even when barrel settings are conservative. Melt temperature is therefore measured at the die rather than inferred from barrel set points. Adapter and die heaters are set no more than 10–15 °C above the target melt temperature to minimise polymer degradation in stagnant flow regions.

Because EF206 carries a nominal 6 g/10 min melt index, it is more shear-thinning than a 2 MI EVA and easier to pump through thin-gauge coextrusion dies, but it has lower melt tension than blown film grades. On monolayer blown film lines, bubble stability at blow-up ratios above 2.5:1 is limited unless the EVA is coextruded with a higher-melt-strength core layer. In coextruded structures the bubble is stabilised by HDPE or polyamide core layers, and EF206 is used only as the skin. Screen pack pressure on a 90 mm extruder typically falls within 10–20 MPa depending on mesh pack and throughput; a steady rise during a run indicates gel accumulation and requires a screen change.

Die gap selection for cast EVA skins is typically 0.5–1.0 mm with air-knife edge pinning. Because the resin has a low melting temperature and a narrow crystalline solidification range, chill roll temperature should be maintained at 10–20 °C to prevent blocking and to set surface gloss. At line speeds above 300 m/min, melt haze and draw resonance may appear if the EVA layer is too thick; reducing the skin to 12 µm or blending with a minor fraction of linear low-density polyethylene is used in some plants to stabilise the melt curtain.

Heat-seal validation for meat and poultry films is performed with a jaw sealer. Under 0.5 s dwell, 2.75 bar jaw pressure, and 85–95 °C interface temperature, seal specimens made with a 20% VA EVA skin commonly enter the plateau seal-strength region measured by ASTM F88. Hot tack force measured per ASTM F1921 is relevant for vertical form-fill-seal lines running high-speed poultry portions; failure occurs when the seal opens before the film web is quenched. Seal-through-contamination with purge simulants has no universal test method, but plant trials typically apply a controlled beef or poultry purge simulant to the seal ledge before jaw closure and then measure residual seal strength per ASTM F88. The outcome depends on fat level, water content, tray flange rigidity, and top web thickness; published universal correction factors are not available.

For vacuum skin packaging, the seal is formed against a rigid tray flange that may be contaminated with purge. The ability of EVA to seal through contamination arises from its low crystalline melting range and its capacity to flow around protein and fat particles under jaw pressure. The resulting seal is not purely adhesive; it is a mechanical interlocking and fusion bond. Seal strength per ASTM F88 is therefore sensitive to tray flange roughness, gauge variation, and sealing temperature. A minimum plateau seal strength of 2.0 N/25 mm after controlled purge exposure is commonly used as a converter specification, but the value is not resin-specific and must be proven on the intended tray material.

At frozen distribution temperatures, the EVA sealant remains flexible. Low-temperature flex-crack resistance of EVA with 20% VA is superior to that of lower-VA EVA and LLDPE because the comonomer reduces crystallinity and broadens the glass transition region. Material and film quality are commonly checked by Gelbo flex testing per ASTM F392 on the finished laminate; the EVA skin contributes to the resistance, but the core layer and tie resins also govern the result.

Regulatory Compliance and Migration Boundaries for Meat Contact Layers

EVA copolymers intended for direct food contact are listed under FDA 21 CFR 177.1350, which authorises ethylene-vinyl acetate copolymers subject to extraction and end-use limitations. In the European Union, multilayer food-contact materials are placed on the market under Commission Regulation (EU) No 10/2011 as amended. The specific migration limit for vinyl acetate monomer is 12 mg/kg in food simulants. Verification of overall migration at the limit of 10 mg/dm² is performed on the finished package, not on the resin pellet alone, because printing inks, adhesives, tie layers, and barrier polymers contribute to the total migrating species. At 20% VA, residual vinyl acetate monomer is normally low after adequate polymerisation and purging, but batch-level certificates of analysis should be retained because converter processing conditions can generate new extractable species through thermal oxidation.

Batch-to-batch melt index variation and comonomer distribution can shift the sealing response. Incoming quality control should include melt index per ISO 1133-1:2022 or ASTM D1238, vinyl acetate content per ASTM D5594, and melting endotherm per ASTM D3418. Viscosity differences between lots of the same nominal 6 MI can change skin thickness distribution in coextrusion; therefore, extruder speed and back-pressure settings may require small adjustments when a new lot is introduced.

When Lower VA Grades or Ionomers Are Substituted in Poultry Lidding Structures

Replacing EF206 with a 9–12% VA EVA or an LLDPE sealant increases the heat-seal initiation temperature into the 100–120 °C range and raises the crystalline melting point. For thin thermoformed tray ledges, that higher temperature can distort the tray flange and slow sealing speed. A 25–28% VA EVA would reduce seal initiation to 65–75 °C, but the film surface becomes softer, blocking tendency increases, and n-hexane extractables may rise; additional slip and antiblock are often required. Ionomers provide higher hot tack and puncture propagation resistance, but their seal initiation is generally not lower than that of a 20% VA EVA and their cost per unit sealant thickness is higher.

Resin selection for meat packaging is not determined by seal initiation alone. A 20% VA, 6 MI EVA offers a compromise between hot tack and blocking. Lower-VA resins may offer higher modulus and lower surface tack, but they require sealing temperatures that can damage thin lidding films. Higher-VA resins may seal at lower temperatures but can build transfer material on sealing jaws and increase reel blocking during storage. The choice of EF206 therefore depends on the sealant layer being coextruded rather than extrusion coated as a thick monolayer.

The 6 MI flow class further differentiates EF206 from other 20% VA EVA grades. Compared with a 2 MI grade, EF206 provides lower melt pressure and better thin-layer distribution in high-speed coextrusion, but lower melt strength in monolayer blown film. Compared with a 25 MI EVA, EF206 retains sufficient melt strength to support the skin layer in deep-draw vacuum packaging without excessive draw resonance.

Tensile properties measured per ASTM D882 on cast films with 20% VA skins show lower machine-direction modulus than LLDPE and lower yield stress than 9–12% VA EVA. For tray lidding, this lower stiffness reduces the force required to peel the film from the flange and minimises tray distortion during sealing. The seal strength plateau is not necessarily higher than that of LLDPE; the advantage is that the plateau is reached at a lower interface temperature. Puncture and tear resistance in the final package are governed by the core barrier layer and total gauge; the EVA skin contributes extensibility but is not a puncture-resistant layer by itself.

On vacuum skin packaging lines, the top web is heated by an upper platen before being drawn over the product. The EF206 skin must not adhere to the platen or to the product surface before the tray flange is contacted. Platen release is controlled by keeping the non-sealing side at a higher melting temperature and by using a release-treated platen. If the top web dwells too long under the heater, the EVA skin can soften and adhere to the product surface, leaving a glossy mark. This is a recognised field failure mode in meat packaging and is managed by shortening dwell time and reducing platen temperature.

Pre-drying is not normally required for sealed pellet containers; however, exposure to ambient relative humidity above 60% RH for extended periods can introduce surface moisture and cause splay or pinholes. The resin should not be dry-blended with strongly alkaline concentrates or amine-based additives because these species can accelerate deacetylation at processing temperatures. Reclaim usage should be limited to clean internal edge trim; post-consumer recyclate is not normally used in direct meat contact layers because sensory and migration risks are difficult to control.