Products · EVOH
Ethylene vinyl alcohol (EVOH) is the workhorse high-barrier copolymer for multilayer food packaging. EVOH offers one of the lowest oxygen transmission rates among commercial polymers at low humidity, making it the standard oxygen-barrier layer in vacuum packaging, retort pouches, and aseptic cartons. The key design variable is ethylene content: lower ethylene (27-32 mol%) gives the highest barrier but requires careful processing; higher ethylene (38-48 mol%) gives easier processing and better humidity resistance at the cost of barrier performance. EVOH is always used as a middle layer in multilayer structures, sandwiched between polyolefin skins (PE, PP) with adhesive tie layers (typically EAA, EMAA, or maleic-anhydride-grafted polyolefins) to protect it from moisture and provide heat seal.
Section 1
A reference overview of the molecular architecture and the design variables that govern the performance of this polymer family.
EVOH is produced by first copolymerizing ethylene and vinyl acetate to EVA, then hydrolyzing the acetate groups to hydroxyl groups. The resulting polymer is a random copolymer of ethylene and vinyl alcohol, with strong intermolecular hydrogen bonding between hydroxyl groups on adjacent chains. This hydrogen bonding is responsible for the very high oxygen barrier at low humidity. However, the same hydrogen bonds also attract and cluster water molecules at high humidity, plasticizing the polymer and reducing barrier performance. This is why EVOH must always be encapsulated between moisture-barrier polyolefin layers in finished structures.
Section 2
Typical property ranges across commercial grades. Test methods are listed in the rightmost column for traceability to public manufacturer data sheets.
EVOH's defining property is its oxygen barrier — among the best of any commercial polymer at low humidity. As humidity rises, barrier drops substantially; in retort applications, the post-retort barrier retention is a key design variable. The ethylene content is the primary lever for balancing barrier against processability and humidity resistance.
| Property · 性能 | Low Ethylene (27-32 mol%) | High Ethylene (38-48 mol%) | Test Method · 测试方法 |
|---|---|---|---|
| Density · 密度 | 1.19 – 1.21 g/cm³ | 1.12 – 1.16 g/cm³ | ASTM D792 |
| Melt Index (210°C/2.16 kg) · 熔指 | 3 – 15 g/10 min | 5 – 25 g/10 min | ASTM D1238 |
| O₂ Transmission (23°C, 0% RH) · 氧透过 | 0.3 – 1.5 cc·20µm/m²·day·atm | 3 – 10 cc·20µm/m²·day·atm | ASTM D3985 |
| O₂ Transmission (23°C, 80% RH) · 高湿氧透过 | 2 – 10 (vs ~0.5 dry) | 20 – 80 | ASTM D3985 |
| Tensile Strength · 拉伸强度 | 70 – 110 MPa | 55 – 90 MPa | ASTM D638 |
| Elongation at Break · 断裂伸长 | 200 – 350 % | 300 – 500 % | ASTM D638 |
| Melting Point · 熔点 | 180 – 195 °C | 155 – 175 °C | DSC |
Section 3
The major application areas for this polymer family, each illustrated with a brief description of how the material is specified and used.
EVOH is the standard oxygen-barrier layer in vacuum bags, retort pouches, modified atmosphere packaging (MAP), and aseptic cartons. Typical constructions: PE / tie / EVOH / tie / PE (5-layer), PP / tie / EVOH / tie / PP (thermoforming trays), PET / tie / EVOH / tie / PE (clear high-barrier pouches).
EVOH can be co-extruded with PE, PP, and PA in 5- to 9-layer structures for food, medical, and industrial barrier films. Modern 9-layer lines allow nano-layer distribution of EVOH to further improve barrier while reducing cost.
Beyond food, EVOH is used in chemical barrier films (e.g., solvent containment), fuel cell membranes, and barrier layers in agricultural mulch films where oxygen and odor barrier are required.
EVOH barrier structures protect fragrances, volatile actives, and oxygen-sensitive ingredients in cosmetic tubes, jars, and sachets. Common in premium skincare where product stability drives packaging cost.
Section 4
Key processing parameters and equipment considerations. Contact our business manager for grade-specific processing recommendations.
| Melt Temperature | 190 – 230 °C; moisture must be < 0.3% to avoid hydrolysis degradation |
| Tie Layer | EAA, EMAA, or maleic-anhydride-grafted polyolefin (typically 5-8 g/m² in 5-layer structures) |
EVOH must be dried 4-8 hours at 80-100 °C before extrusion to prevent molecular-weight loss and bubble formation. Co-extrusion with PE/PP requires precise melt temperature matching — EVOH typically runs 10-20 °C hotter than the polyolefin skin. The structure must encapsulate EVOH between moisture barriers for the design oxygen barrier to be realized in use.
Section 5
A summary of when this polymer family is the right choice and what to consider as alternatives. For project-specific grade selection, contact our business manager.
Choose EVOH when the application requires very low oxygen transmission at low humidity and the structure can protect EVOH from direct moisture exposure via polyolefin skin layers. For high-humidity end uses (e.g., hot-fill, retort at > 121 °C), consider PVdC-coated films or PVDC latex-coated structures. For pure mechanical barrier without oxygen requirement, oriented PA (BOPA) or PET is more cost-effective.
Section 6
Reference grades from publicly available manufacturer catalogs. Complete catalog available on request.
| Grade | Manufacturer | Key Properties | Typical Use |
|---|---|---|---|
| Soarnol™ DC3203Internal snapshot · original TDS on request | Mitsubishi Chemical | 32 mol% ethylene · 3 MI · High barrier | Retort pouch · MAP |
| Soarnol™ ET3803No vendor TDS · source on request | Mitsubishi Chemical | 38 mol% ethylene · 3 MI · Processable | Co-extrusion · Thermoforming |
| EVAL™ F101BInternal snapshot · original TDS on request | Kuraray | 32 mol% ethylene · 1.6 MI · Standard | Flexible packaging · Vacuum bag |
| EVAL™ LR171BNo vendor TDS · source on request | Kuraray | 27 mol% ethylene · 4 MI · Highest barrier | Aseptic carton · Sensitive food |
Section 7
Cross-references to industry-specific applications and case studies.