Elevate EB502 EVA Copolymer Resin,12.5% VA,0.55 MI,Heat Seal Layer Grade

In coextruded food packaging, EB502 is assigned to the sealant layer because the 12.5% vinyl acetate content lowers seal initiation relative to unmodified LDPE while retaining adequate melt strength at 0.55 dg/min (ASTM D1238, 190 °C/2.16 kg). Three-layer blown film lines with a 60–90 mm die and 1.8–2.2 mm die gap run the resin at melt temperatures of 185–210 °C. The layer distribution is typically 15–25% sealant, 50–60% LDPE core, and 20–25% outer skin. A converter blend of 70–85 wt% EB502 with 15–30 wt% LDPE having MI 0.25–0.5 dg/min is used to reduce backpressure without raising seal initiation above 95 °C. The blend is fed to a grooved-feed single-screw extruder with 30:1 L/D and a barrier screw. Film is formed at a blow-up ratio of 2.0–2.5:1 and frost line height of 200–350 mm above the die. Terminal webs include frozen vegetable pouches, dry soup sachets, and snack laminates. Food-contact compliance for the US is reviewed under 21 CFR 177.1350; for EU markets, Regulation 10/2011 applies with an overall migration limit of 10 mg/dm² and a vinyl acetate specific migration limit of 12 mg/kg. Pre-drying at 65–75 °C for 1–2 h is applied when storage RH exceeds 60% to limit surface moisture defects. Processing above 230 °C is avoided because acetic acid by-products from EVA degradation can corrode die lips and downstream metal surfaces.

What Limits Hot Tack Performance When EB502 is Blended with mLLDPE for High-Speed VFFS Lines?

Vertical form-fill-seal packaging of fresh produce and bakery goods runs at 80–120 packs/min. Under these conditions, the sealant layer must maintain hot tack before the seal cools. EB502 contributes seal initiation below 95 °C; however, the 0.55 dg/min MI can restrict molecular mobility at high sealing speeds. A converter blend of 60–80 wt% EB502 with 20–40 wt% mLLDPE having MI 0.8–1.0 dg/min is used to widen the hot tack plateau. The film is produced on a 5-layer cast coextrusion line with chill roll temperature 18–22 °C and sealant layer thickness 8–12 µm in a 40–60 µm total web. Slip and antiblock additives are introduced as a 5 wt% masterbatch at 2–4 wt%, yielding 500–1,200 ppm erucamide and 1,000–2,000 ppm silica in the sealant layer. These levels are adjusted because erucamide migration reduces hot tack. Hot tack is measured per ASTM F1921, heat seal strength per ASTM F2029, and coefficient of friction per ASTM D1894. If seal bar temperature exceeds 140 °C, the hot tack window narrows and seal-through-contamination failures increase on dusty snack lines. Published data for this specific resin configuration is limited; line-side calibration against ASTM F2029 is required. Terminal packages include pillow bags for washed salad greens, frozen fruit, and bakery items. Compliance is reviewed under 21 CFR 177.1350 and Regulation 10/2011.

When Paperboard is Coated with a 15–25 µm EB502 Sealant Web on Extrusion Coating Lines

Paperboard and aluminum foil structures for dry food sachets require a heat sealable surface that also withstands web tension and roll blocking. EB502 is applied on an extrusion coating line at 15–25 µm coating thickness over a paperboard or foil substrate. Because the MI is 0.55 dg/min, melt temperature at the die is held at 200–225 °C; above 230 °C oxidative degradation generates acetic acid and reduces adhesion. Paperboard is preheated to 80–100 °C to remove surface moisture and improve bond. Aluminum foil requires a primer or coextruded tie layer because direct adhesion of EVA to foil is moderate. Coating weight is controlled by line speed and chill roll temperature 12–18 °C. The sealant layer is often coextruded with 10–20% LDPE to improve drawdown and edge stability. Terminal packages include condiment sachets, dry beverage pouches, and paperboard lidding for yogurt cups. US compliance for coated paperboard falls under 21 CFR 176.170; EU food contact compliance follows Regulation 10/2011. The resin is not a tie resin; direct adhesion to polyamide or polyester substrates requires an adhesive tie layer.

Medical device sterile barrier films use EB502 as the sealant layer for rigid trays made from PETG, PS, or PVC. The sealant web is coextruded as a 30–60 µm layer onto a polyester or polyamide carrier film, or used as monolayer pouch stock. The sealant layer generally accounts for 20–35% of total web thickness. Sealing to rigid trays is performed at 120–150 °C with dwell 0.5–1.5 s and pressure 300–600 kPa. Seal strength is measured per ASTM F88 and must meet the package design specification; there is no single universal limit. Sterile barrier integrity is validated under ISO 11607-1, and biocompatibility of the packaging material is assessed under ISO 10993-5 for cytotoxicity. The resin carries no antimicrobial function; terminal sterilization is performed by ethylene oxide, gamma, or electron beam after sealing. The sealant must survive the chosen dose without embrittlement or seal strength loss. Published data for EB502 in validated sterile barrier systems is limited, so each converter must complete package validation with the exact tray material, sealant thickness, and sterilization cycle. Terminal products include pouches for syringes, IV administration kits, and surgical instrument trays. Processing above 230 °C is avoided to prevent acetic acid formation that could compromise film clarity and odor.

Pharmaceutical Blister Lidding Sealant and PVC/PVDC Compatibility

Pharmaceutical blister lidding stock uses aluminum foil extrusion-coated or laminated with EB502 as the heat seal layer for sealing to PVC or PVDC blister cavities. The coating weight is 8–20 g/m² on 20–25 µm aluminum foil. Seal dwell times on rotary blister machines are 0.4–1.2 s at 160–190 °C. The 12.5% VA content provides a balance between low organoleptic impact and sealability to PVC. Low odor and taste transfer are critical for pharmaceutical packaging; sensory evaluation is performed according to ISO 13302. US food and drug contact is reviewed under 21 CFR 177.1350; EU materials comply with Regulation 10/2011 and pharmacopoeial requirements for packaging materials. The sealant is formulated with a slip package below 800 ppm to avoid interference with print adhesion on the foil lidding. Terminal products include unit-dose tablet blister packs, capsule lidding, and powder sachets. Because EVA is sensitive to residual acetic acid above 230 °C, coating lines are run with vented extruders and stabilized purge cycles. Published data for EB502 in pharmaceutical blister lidding is limited; each structure requires migration and organoleptic verification against the finished drug product.

A Melt Index of 0.55 dg/min Increases Head Pressure but Stabilizes Low-Thickness Cast Sealant Webs

This process boundary is relevant when EB502 is run on high-output cast film and extrusion coating lines. The low MI 0.55 dg/min produces higher head pressure than a 2.0 dg/min LDPE at the same screw speed. On a 90 mm extruder at 200 kg/h, operators observe backpressure differences that may require a 30:1 L/D barrier screw and grooved feed section. Die gaps below 0.8 mm increase shear heating and can initiate melt fracture at the die lip. Melt temperatures are controlled at 200–225 °C with melt pressure monitored at the screen pack. A 100/120 mesh breaker plate combination is used to trap degraded gel particles. The low MI also stabilizes the melt curtain and reduces draw resonance in low-thickness sealant webs down to 8 µm. The resin is blended with 10–20 wt% LDPE or mLLDPE to lower backpressure without changing the 12.5% VA heat seal response. Batch-to-batch variance in seal initiation is controlled by resin MI tolerance of ±0.05 dg/min and VA content within ±0.5%. Terminal webs include cast sealant films for frozen food laminations and coated paperboard for dry goods. Operational boundaries include pre-drying after storage at RH above 60% and avoiding additive packages containing free amines that can react with acidic degradation by-products.