| HS Code | 172147 |
| Oxygen Barrier | Very high, typical OTR < 0.1 cm³/(m²·day·bar) |
| Ethylene Content | Typically 27-32 mol% for deep draw grades |
| Melt Flow Index | 1.0-3.5 g/10 min (190°C, 2.16 kg) |
| Density | 1.19-1.21 g/cm³ |
| Melting Point | 183-191°C |
| Glass Transition Temperature | 55-72°C |
| Tensile Strength | 60-80 MPa |
| Elongation At Break | 230-380% |
| Water Vapor Transmission Rate | 1-3 g/(m²·day) at 38°C, 90% RH |
| Deep Draw Thermoforming Temperature Range | 110-170°C |
As an accredited EVOH for Deep Draw Thermoforming factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged as 25 kg net in sealed, moisture-proof multi-layer bags, with desiccant, ensuring EVOH purity for deep draw thermoforming. |
| Container Loading (20′ FCL) | EVOH resin pellets in sealed bags, palletized for 20′ FCL, secured to prevent moisture absorption during deep draw thermoforming transport. |
| Shipping | EVOH for deep draw thermoforming ships as non-hazardous resin pellets in moisture-barrier lined bags, boxes, or octabins. Protect from humidity and direct sunlight; store dry at ambient temperature. Ensure containers are sealed and labeled with grade, batch, and handling instructions. Avoid compression damage during transit. |
| Storage | Store EVOH resin in a cool, dry, well-ventilated area, away from direct sunlight and heat sources. Keep containers tightly sealed to prevent moisture absorption, which compromises barrier properties. Maintain storage temperature below 30°C and relative humidity under 50%. Use within six months of receipt to ensure consistent deep draw thermoforming performance. |
| Shelf Life | Store in sealed, dry conditions. Shelf life typically 1–2 years from manufacture date, maintaining barrier properties for deep draw thermoforming. |
In refrigerated modified-atmosphere packaging for wet, high-water-activity foods such as processed sliced meat, fresh filled pasta, and soft cheese, EVOH with 38 mol% ethylene is coextruded as the central barrier layer in a PP/EVOH/PP sheet. The EVOH layer is specified at 25–50 µm, corresponding to 3–5 wt% of the total sheet mass when the finished sheet is 1.2–1.8 mm. Direct food-contact compliance is established under FDA 21 CFR 177.1360 and EU Regulation (EU) No 10/2011, with oxygen transmission verified at 23 °C and 0 % RH according to ASTM D3985. A 25–50 µm EVOH layer in PP/EVOH/PP sheet typically measures below 0.5 cm³/(m²·day·atm) at 0 % RH, but the barrier value degrades when the formed tray is exposed to retail display humidity above 60 % RH because EVOH is moisture plasticized. The sheet is produced on a coextrusion line equipped with a single-screw EVOH extruder with a 24:1 L/D barrier screw, compression ratio 2.5:1 to 3.0:1, and chrome-plated barrel, melt temperature maintained at 210–225 °C; the PP skins are processed at 230–250 °C through a feedblock and flat die with die gap 1.5–2.5 mm. Thermoforming is conducted as plug-assisted pressure forming with aluminum plug temperature 95–110 °C, sheet surface temperature 160–175 °C, and cavity draw ratio 2.0:1 to 3.0:1. Terminal products are lidded tray formats for high-speed filling and sealing lines, including rectangular MAP trays for processed meat and cream cheese, deep tubs for bulk fresh pasta, and compartmented trays for mixed salad; each requires post-forming EVOH continuity at the corner radius, with minimum residual EVOH thickness not below 8 µm to avoid pinhole barrier failure.
At the sealing flange, local EVOH thinning from plug displacement must be controlled because the corner and sidewall carry the primary barrier load. On production-scale thermoforming machines running 25–35 cycles/min, sheet temperature variation of ±3 °C across the web width shifts corner wall thickness by more than 10 %, which occasionally drops EVOH below the 8 µm threshold and raises pinhole rates. Pre-drying of EVOH pellets at 80–90 °C for 4–6 h is mandatory when bulk silo humidity exceeds 60 % RH; residual moisture should be below 0.3 wt% before extrusion, otherwise the melt exhibits surface bubble formation and local barrier layer rupture. Tie layers are specified as maleated polypropylene at 15–25 µm each side; this thickness range balances adhesion and cost while preventing delamination in the flange area after sealing at 150–170 °C.
| Application | Food-contact / regulatory framework | Barrier test designation | Thermoforming / mechanical test |
|---|---|---|---|
| Refrigerated MAP trays | FDA 21 CFR 177.1360; EU 10/2011 | ASTM D3985 | ISO 527-3 |
| Retortable ready-meal trays | FDA 21 CFR 177.1390; EU 10/2011 | ASTM D3985 after retort | ASTM D638 |
| Single-serve coffee capsules | FDA 21 CFR 177.1360; EU 10/2011 | ASTM D3985 | ISO 527-3 |
Retortable ready-meal trays differ from refrigerated MAP formats because the PP/EVOH/PP sheet must survive 121 °C saturated steam for 30 min without delamination or irreversible barrier loss. The EVOH layer is selected from 44 mol% ethylene grades to reduce moisture sensitivity, specified at 30–60 µm, representing 4–6 wt% of a 1.5–2.5 mm sheet. Direct compliance is assessed under FDA 21 CFR 177.1390 for high-temperature laminate structures and EU Regulation (EU) No 10/2011, including overall migration tests conducted on the retorted formed article. Oxygen transmission is verified before and after retort according to ASTM D3985 at 23 °C and 0 % RH; formed tray OTR commonly increases by a factor of 2.0–3.0 at 50 % RH after retort because residual moisture in EVOH plasticizes the vinyl alcohol segments, and barrier recovery may require 24–48 h dry-out at 23 °C. Coextrusion uses a high-crystallinity PP homopolymer skin and maleated PP tie layers at 25–40 µm each side. The sheet is extruded with polished cooling rolls set at 80–95 °C, then thermoformed at sheet surface temperature 175–190 °C using plug-assisted pressure forming. The retort cycle is run under overpressure of 2.2–2.8 bar to prevent dome deflection and flange curl. Terminal products include shallow rectangular ready-meal trays, deep-draw pet food bowls, and multi-chamber trays for rice-and-sauce combinations; post-retort seal strength is measured by ASTM F88/F88M on the flange after the thermal process.
Field failure is most commonly observed when EVOH layer thickness drops below 25 µm during wall thinning at the bottom corner; after retort, local water absorption in that thinned region exceeds 5 wt%, generating interfacial swelling stress that exceeds tie-layer peel adhesion. If tie-layer thickness is below 20 µm, the resulting stress produces microvoids, which are visible as opaque patches in the EVOH layer. Production lines therefore specify minimum residual tie-layer thickness of 15 µm at the corner and minimum EVOH thickness of 10 µm; these are verified by cross-section microscopy and not inferred from sheet input. Delamination also appears at the flange when sheet temperature during forming is below 170 °C, because the PP skins do not fully wet the tie layer under the compression of the cavity seal ring, leaving a weak boundary layer that fails during retort pressure cycling.
When single-serve coffee capsules are thermoformed from multilayer sheet, the EVOH barrier layer is selected to protect roasted ground coffee at water activities below 0.3 and to preserve volatile aroma compounds during 12–18 months of shelf life. The EVOH layer is specified at 20–40 µm, equivalent to 3–6 wt% of a PP/EVOH/PP sheet with total thickness 0.8–1.5 mm. Compliance is established under EU Regulation (EU) No 10/2011 and FDA 21 CFR 177.1360; oxygen transmission is tested according to ASTM D3985 at 23 °C and 0 % RH. The downstream process is plug-assisted thermoforming with a heated aluminum plug at 90–105 °C, sheet surface temperature 160–175 °C, and cavity depth 25–32 mm for an aperture diameter of 37–44 mm, producing a depth-to-aperture ratio greater than 0.6. Terminal product types include oxygen-sensitive coffee capsules sealed with aluminum lidding, dairy creamer pods, and multilayer capsules for soluble cocoa drinks. The critical control point is residual EVOH thickness at the bottom corner after wall thinning; if the initial EVOH layer is 20 µm and wall thinning is 60 %, the remaining EVOH is 8 µm, which is the practical lower limit for pinhole-free coffee packaging. On high-cavitation tools running 30–45 cycles/min, sheet temperature variation across the web must be held within ±2 °C to prevent thickness variation that reduces barrier performance in the outer cavities. Pre-drying of EVOH to below 0.3 wt% moisture is required before coextrusion; otherwise hydrolytic degradation creates gel specks and barrier layer discontinuities.
A sterile barrier blister for a pre-filled syringe demands a forming sheet with controlled oxygen and moisture permeation after ethylene oxide sterilization. PETG/EVOH/PETG sheet is used for its clarity and formability; the EVOH layer is 15–35 µm, representing 2–4 wt% of a 0.6–1.2 mm sheet. Compliance is governed by ISO 11607-1:2019 for sterile barrier systems and USP <671> for moisture vapor transmission; oxygen barrier is verified according to ASTM D3985, water vapor transmission according to ASTM F1249, and seal strength according to ASTM F88/F88M. The downstream process is cleanroom thermoforming under ISO 7 conditions, using plug-assisted pressure forming with PTFE-coated aluminum plugs at 105–120 °C and sheet surface temperature 120–145 °C. Draw ratios are typically 2.0:1 to 2.8:1, and terminal product types include PETG/EVOH/PETG trays for pre-filled syringes, surgical instrument blisters, and implant trays. The key processing limitation is EVOH moisture uptake during steam or autoclave sterilization; if saturated steam reaches the EVOH layer through unsealed edges, barrier OTR rises because EVOH moisture sensitivity is not reversible within the sterile barrier lifetime. Ethylene oxide sterilization is preferred because the dry gas cycle does not load EVOH with liquid water, but residual gas retention must be validated under ISO 10993-7:2008. On production lines, batch-to-batch variation in PETG shrinkage at the forming window changes corner thinning of EVOH; therefore the minimum post-forming EVOH thickness is set at 6 µm, verified by optical microscopy on three cavity positions per tool. If the draw ratio exceeds 2.8:1, published data for this specific configuration is limited, and validation must include dye-penetrant discontinuity testing of the EVOH layer.
Deep-draw HDPE/EVOH/HDPE containers for solvent-based agrochemical formulations are designed for hydrocarbon permeation resistance rather than oxygen scavenging; the EVOH layer is specified at 20–40 µm in a 2.0–3.0 mm sheet, equivalent to 2–4 wt% of total sheet mass. Compliance for transport packaging is based on the UN Recommendations on the Transport of Dangerous Goods, Chapter 6.1 rigid plastics provisions, with liquid permeation tested according to ASTM D2684; oxygen barrier is not the primary specification but is monitored by ASTM D3985 at 23 °C and 50 % RH. The downstream production process is coextrusion of HDPE skins with EVOH and maleated polyethylene tie layers, followed by plug-assisted pressure forming at sheet surface temperature 170–190 °C, with mold temperature 35–50 °C to control HDPE crystallization. Terminal product types include deep-draw pail liners for 5–20 L solvent containers, agrochemical measurement trays, and barrier lids for drum inserts. The operational limitation is chemical compatibility: EVOH lowers hydrocarbon permeation but does not protect HDPE from environmental stress cracking if aggressive ester or ketone solvents contact stressed flange areas; compatibility must be verified by ASTM D543 immersion tests. In addition, EVOH moisture absorption at ambient humidity above 80 % RH will reduce barrier performance during warehouse storage in tropical climates, so outer HDPE skins are kept above 1.0 mm on each side to slow moisture ingress.
If an oxygen-sensitive cosmetic formulation such as retinol serum or vitamin C powder is packaged in a thermoformed EVOH barrier cup, the sheet structure is commonly PP/EVOH/PP or PE/EVOH/PE, with an EVOH layer specified at 15–25 µm, representing 2–4 wt% of a 0.8–1.4 mm sheet. Regulatory assessment is performed under EU Regulation (EC) No 1223/2009 for the finished cosmetic product; packaging compatibility is documented according to ISO 22715:2006, and where food-grade reassurance is desired, migration reference is made to EU Regulation (EU) No 10/2011 but it is not legally decisive for cosmetics. Oxygen barrier is tested by ASTM D3985 at 23 °C and 0 % RH, and water vapor transmission by ASTM F1249. The downstream production process is plug-assisted pressure forming at sheet surface temperature 150–165 °C, plug temperature 90–100 °C, and draw ratio 2.0:1 to 2.5:1. Terminal product types include single-dose retinol serum trays, vitamin C powder pods, and oxygen-sensitive cream cups sealed with aluminum or PP lidding. The limitation specific to this sector is fragrance and active migration: EVOH is not a barrier to all volatile aroma compounds, and low-molecular-weight lipophilic actives may plasticize the EVOH layer if they migrate through the tie layer, raising OTR. Published data for this specific configuration is limited, so compatibility testing under accelerated storage at 40 °C and 75 % RH for 3–6 months is required before scaling. On production-scale tools, static build-up on the sheet surface can cause cosmetic powder adhesion; corona treatment above 42 mN/m on the sealing surface is applied after forming, but not before thermoforming, because surface oxidation changes friction against the plug.
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An ethylene-vinyl alcohol copolymer designated for deep draw thermoforming is introduced as a buried core barrier layer in coextruded sheet, typically encapsulated between polypropylene or polyethylene cap layers and maleic anhydride-grafted polyolefin tie layers. The product is specified with a nominal ethylene content of 32 mol%, a density of 1.19 g/cm³ per ISO 1183-1:2019, and a melt flow rate of 1.6–3.2 g/10 min at 210 °C under 2.16 kg load per ISO 1133-1:2022. Oxygen transmission rate of the cast film at 20 °C and 65% RH is typically 0.20–0.50 cm³·mm/(m²·day·atm) when measured according to ISO 14663-2, and the melting point ranges from 158 °C to 183 °C depending on ethylene content per ISO 11357-3. The material is intended for plug-assisted deep draw where area draw ratios reach 2.5:1 to 3.0:1; it is not recommended for monolayer processing because moisture absorption above 60% RH reduces barrier and causes surface defects.
| Parameter | Representative specification | Test method |
|---|---|---|
| Ethylene content | 32–38 mol% | Supplier specification |
| Density | 1.17–1.21 g/cm³ | ISO 1183-1:2019 |
| Melt flow rate | 1.6–3.2 g/10 min at 210 °C, 2.16 kg | ISO 1133-1:2022 |
| Melting point | 158–183 °C | ISO 11357-3 |
| Oxygen transmission rate | 0.20–0.50 cm³·mm/(m²·day·atm) | ISO 14663-2 at 20 °C, 65% RH |
| Moisture content after drying | <0.10% | Karl Fischer titration |
In production, the EVOH must be pre-dried in a desiccant dryer to 0.10% moisture or lower when ambient relative humidity exceeds 60%. Drying conditions are typically 90–100 °C for 4–6 h, with dew point maintained below −40 °C. The EVOH layer is coextruded at melt temperatures between 210 °C and 230 °C; residence time should not exceed 20 min, and shutdown purging is performed with low-viscosity polyethylene. Target EVOH thickness in the preform sheet is 3–8 µm within a total sheet thickness of 500–1500 µm, depending on part depth and required oxygen transmission. Trim scrap containing EVOH is not returned to the barrier layer at levels above 10–15 wt% because regrind causes viscosity shifts, gel formation, and fish eyes that become pinholes after drawing.
Sheet surface temperature is a critical control variable. For a 32 mol% ethylene grade, the forming window is 165–175 °C; excursions above 180 °C produce local thinning and pinholes in the EVOH core, while temperatures below 160 °C generate corner microcracks and visible stress whitening. Zoned ceramic infrared heaters with closed-loop pyrometer feedback are used to maintain sheet temperature variation within ±5 °C across the forming area. Plug-assist temperature is maintained at 90–120 °C using syntactic foam or PEEK plug materials with low thermal conductivity. Plug speed is typically 200–400 mm/s; lower speeds increase cycle time and allow premature cooling, while higher speeds induce localised stretching and delamination at the EVOH layer.
At draw ratios beyond 2.5:1, the EVOH layer final thickness can fall from 5 µm to 1.7 µm, and oxygen transmission increases proportionally. Published data for this specific configuration is limited; processors should validate shelf-life performance on formed parts rather than cast film data. Edge stress is reduced by keeping the EVOH layer at least 2 mm away from the trim boundary and by increasing ethylene content to 38–44 mol% only when oxygen barrier requirements allow the higher transmission values associated with higher ethylene content.
Coextrusion lines for deep draw sheet typically use a single-screw extruder with 24:1 to 30:1 L/D ratio, a barrier screw, and a gear pump. Apparent viscosity of the 32 mol% grade at 210 °C and 100 s⁻¹ is approximately 1.0·10³ Pa·s; viscosity is more temperature-sensitive than shear-sensitive, so barrel zones are profiled from 180 °C at the feed throat to 230 °C at the die adaptor. Feedblock configuration is usually PP/tie/EVOH/tie/PP or PE/tie/EVOH/tie/PE. Maleic anhydride-grafted polyolefin tie layers are maintained at 2–5 µm each side of the EVOH layer; reduction below 2 µm causes delamination at deep draw corners. Batch-to-batch variation in melt flow rate of ±0.2 g/10 min can shift the forming window slightly and must be compensated by sheet temperature adjustment.
The dominant limitation is moisture interaction. EVOH oxygen transmission increases by roughly one order of magnitude when relative humidity rises from 65% to 85%; therefore the outer polyolefin layers must provide water vapour shielding. In high-humidity applications, a 32 mol% ethylene grade is preferred over a 27 mol% grade because the higher ethylene content reduces moisture sensitivity but sacrifices dry-state barrier. The second limitation is thickness uniformity after drawing. Thinning at corners reduces the barrier path length; if the EVOH layer falls below 1.5 µm, pinholes increase and oxygen transmission becomes dominated by defects rather than polymer permeability. Third, crystallinity development during plug-assisted stretching is non-uniform; fast cooling on the plug side freezes an amorphous skin while the opposite side develops spherulitic structure, altering barrier locally.
Process conflict arises between barrier optimisation and drawability. Higher ethylene content improves drawability and moisture resistance but raises oxygen transmission coefficient. For a 38 mol% grade, oxygen transmission at 20 °C and 65% RH is typically 0.50–1.00 cm³·mm/(m²·day·atm), roughly double the 32 mol% grade. Conversely a 27 mol% grade may show oxygen transmission of 0.10–0.20 cm³·mm/(m²·day·atm) but cracks at draw ratios above 2.0:1. Selection therefore requires balancing barrier retention with corner cracking. Oxygen transmission measured on a flat sheet per ISO 14663-2 is not a sufficient predictor of formed-part barrier; formed-tray oxygen transmission should be measured according to ASTM F1927-20 at the intended storage humidity.
Additional operational boundaries include avoidance of direct flame treatment on exposed EVOH layers, avoidance of prolonged operation above 240 °C where gel formation accelerates, and exclusion of amine-based processing additives from the EVOH layer because they can catalyse chain scission during extrusion. Food-contact compliance is evaluated under Regulation (EU) No 10/2011 as amended, with overall migration limit 10 mg/dm² and specific migration limits for ethylene and vinyl alcohol as defined in the regulation. For high-humidity or hot-fill applications, polypropylene cap layers are preferred over polyethylene because they provide lower water vapour transmission at elevated temperatures and maintain part stiffness during filling.
Compared with PVDC, EVOH for deep draw thermoforming has a narrower forming window and greater moisture sensitivity, but it does not release hydrogen chloride during processing and has lower density, enabling lighter multilayer sheet. PVDC remains useful where humidity stability and a wider heat seal range are prioritized; however, extrusion equipment must use corrosion-resistant screws, dies, and downstream components. Compared with nylon 6 and MXD6, EVOH provides substantially lower oxygen transmission under dry conditions. Nylon 6 and MXD6 offer higher elongation at break and better corner toughness, which is advantageous for aggressive deep draw, but their oxygen barrier coefficients are approximately one to two orders of magnitude higher than EVOH at 20 °C and 65% RH. MXD6 is sometimes blended or coextruded with EVOH to moderate moisture sensitivity and improve drawability, though the blend changes optical clarity and oxygen transmission.
Compared with aluminium foil, EVOH provides transparent microwaveable parts with lower oxygen barrier but without metallic pinholes formed during flexural fatigue; foil is used only when oxygen transmission must be below 0.01 cm³·mm/(m²·day·atm). Within the EVOH family, deep draw grades differ from blow film and injection molding grades by having ethylene contents of 32–44 mol%, controlled crystallization half-time, and lower melt viscosity. These grades are not interchangeable with high-barrier 27 mol% film grades in deep draw lines; the higher barrier grade may exhibit corner cracking and melt fracture when stretched beyond 2.0:1. Conversely, grades with ethylene content above 44 mol% are more flexible and easily drawn but may no longer meet the oxygen transmission target for oxygen-sensitive food packaging.
Commercial use is concentrated in coextruded barrier trays, cups, and blister packs for oxygen-sensitive foods and medical devices. The EVOH layer is never used as a cap layer; direct contact with water, acidic media, or high-humidity headspace must be prevented by the adjacent polyolefin layers. Formed parts requiring sterilisation or hot-fill above 100 °C require special validation because EVOH barrier retention under simultaneous heat and moisture stress can shift by more than one order of magnitude. Processors selecting a deep draw EVOH grade must verify formed-part oxygen transmission, corner thickness, and delamination resistance on production-scale plug-assist tooling rather than relying exclusively on supplier data sheets.
