EVOH EVAL E105P

A five-layer polypropylene / maleic anhydride grafted tie / EVAL E105P / tie / polypropylene sheet is processed on a three-extruder coextrusion line for thermoformed rigid food containers. The barrier-layer pellets are dried in a desiccant dryer with supply air dew point not higher than −40 °C, achieving residual moisture below 0.1% and preferably below 0.05% before entering the feed throat. The extruder assigned to the EVOH layer uses a single-flight barrier screw with L/D of at least 24:1 and compression ratio between 2.8:1 and 3.5:1. Barrel temperatures are profiled from 180 °C at the feed throat to 225 °C at the metering section, with adapter and flat die zones held between 220 °C and 225 °C. Accumulated residence time above 230 °C is limited to 30 minutes, because thermal degradation of vinyl alcohol segments produces conjugated species and gel particles that appear as lens-shaped inclusions in the sheet. The barrier layer thickness is maintained at 2–5% of total sheet thickness, corresponding to 30–75 μm in sheet of 1.5 mm. Oxygen transmission through the formed container sidewall is measured according to ASTM D3985 at 23 °C and 50% RH; a continuous 20 μm EVOH layer typically yields an oxygen transmission rate in the range 0.6–0.9 cm³/(m²·day·atm), while thinner regions near deep-draw corners increase local transmission. Regrind containing EVOH is restricted to the polypropylene outer and inner layers at addition levels of 10–20%, because barrier-layer regrind introduces grafted anhydride groups and crosslinked gel seeds that reduce interlayer clarity and burst strength. Compliance with European food contact legislation is verified under EU 10/2011, with overall migration measured by EN 1186; United States clearance is typically covered by the manufacturer’s food contact substance notification for ethylene vinyl alcohol copolymer.

What Limits EVOH Layer Distribution in Five-Layer Cast Film for Modified Atmosphere Packaging?

Layer distribution in a polyethylene / tie / EVAL E105P / tie / polyethylene cast film is governed primarily by viscosity matching at die lip shear rates and by interfacial stress across the feedblock. When EVAL E105P is run in the centre layer at a target thickness of 3–5 μm, the melt viscosity of the tie resin must remain within the same order of magnitude as the EVOH at processing shear rates, otherwise the barrier layer breaks into wavy, non-continuous bands. Cross-web thickness variation is measured on microtomed sections under polarised light; a deviation greater than ±10% from nominal barrier thickness reduces the oxygen barrier and creates seal failure points. The oxygen transmission rate of the cast film measured by ASTM D3985 at 23 °C and 50% RH is commonly between 0.4 and 0.8 cm³/(m²·day·atm) for a five-layer film containing 5 μm of EVOH; moisture plasticization at 85% RH raises the transmission rate by a factor of 3–5. Water vapour transmission measured by ASTM F1249 at 38 °C and 90% RH is controlled mainly by the polyethylene layers, and the EVOH layer does not function as a WVTR barrier under these conditions. Tie-layer choice is restricted to maleic anhydride grafted polyolefins with controlled gel content; excess peroxide residue in the tie resin attacks EVOH during film extrusion and generates interfacial gels. Edge trim containing EVOH cannot be re-fed into the cast film without filtration at 20 µm or finer, because vinyl alcohol segments undergo rapid gelation during repeated heat histories. Published data for this specific configuration is limited at line speeds above 250 m/min; trials are required to confirm layer continuity.

In automotive fuel tank blow moulding, a six-layer parison of high-density polyethylene / regrind / tie / EVAL E105P / tie / high-density polyethylene is formed on an accumulator head machine. The EVOH layer is positioned between two tie layers to prevent delamination during parison inflation and during vehicle vibration. The barrier layer normally occupies 2–3% of total tank wall thickness, which for a 6 mm wall corresponds to 120–180 μm of EVOH. Melt temperatures in the EVOH extruder are held between 220 °C and 230 °C; head temperatures above 235 °C during interruptions longer than 20 minutes create gel strings at the parison surface and require purge with polyolefin before production resumes. Hydrocarbon permeation performance is evaluated under evaporative emission test procedures in 40 CFR Part 86, with the tank installed in a sealed housing and subjected to diurnal temperature cycles; the EVOH layer reduces permeation of non-oxygenated gasoline components by more than one order of magnitude relative to monolayer high-density polyethylene in the same wall thickness under the same sealed-housing procedure. However, fuel blends containing high concentrations of ethanol or methanol plasticize the EVOH layer through polar interaction, and the barrier improvement over high-density polyethylene is reduced. The effect is particularly pronounced with continuous exposure to E85 fuel at temperatures above 40 °C; published data for E105P under such ageing conditions is limited. Adhesion is checked after immersion in test fuel for 1000 hours at 60 °C, with no delamination at the tie layer interface being the production acceptance criterion. Weld flash and post-consumer regrind containing EVOH must be segregated, because dispersed EVOH domains in the high-density polyethylene regrind layer cause local viscosity discontinuities and pinholes during parison welding.

When E105P Replaces Fluorinated HDPE in Agrochemical Container Blow Moulding

Rigid agrochemical containers are blow moulded as high-density polyethylene / tie / EVAL E105P / tie / high-density polyethylene structures when surface fluorination of monolayer high-density polyethylene is replaced by a coextruded barrier. The EVOH layer is set at 2–3% of total wall thickness, typically 50–90 μm in a 3 mm wall, and is protected from product contact by the inner high-density polyethylene layer. Weight-loss permeation testing according to ASTM D2684 at 50 °C for 28 days provides comparative data for solvents such as xylene, toluene, and methyl isobutyl ketone. Aromatic hydrocarbon permeation through the multilayer wall is below the detection limit of the gravimetric procedure when the EVOH layer is continuous, whereas monolayer high-density polyethylene containers exhibit measurable weight loss within the same period. Polar solvents with strong hydrogen-bonding capacity, including methanol and dimethylformamide, plasticize the EVOH layer and reduce its barrier function; the container is therefore not a universal solvent package. Blow moulding process control requires the barrier layer extruder temperature to remain below 225 °C, and the parison drop time is minimised to prevent cooling-induced crystallization of the EVOH layer before inflation. Crystallinity differences across the EVOH layer can create local stress concentrations at fold lines in the article. The outer high-density polyethylene layers are supplied at a melt temperature of 230 °C, and the tie layers at 225 °C. Interlayer adhesion is verified by peel testing of cut sections after 24 hours conditioning at 23 °C and 50% RH. Start-up and colour-change scrap cannot be recycled into the barrier layer; it is mixed into high-density polyethylene regrind only at levels below 10% due to gel formation in the recycled melt stream.

Five-layer pipe extrusion for hydronic heating and cooling circuits uses a polyethylene / tie / EVAL E105P / tie / polyethylene structure. The EVOH layer is specified as an oxygen diffusion barrier to prevent corrosion of ferrous components in the circulating water system. In pipes of 16 mm to 32 mm outside diameter, the EVOH layer thickness is held between 100 µm and 150 µm. Oxygen permeability of the finished pipe is measured at 40 °C according to DIN 4726 or ISO 17455; acceptance for oxygen-barrier pipe is commonly set at no greater than 0.1 g/(m²·day) at 40 °C. Layer distribution around the circumference is controlled by spiral mandrel geometry in the coextrusion die; thickness variation greater than ±10% produces local areas of higher oxygen diffusion and can lead to test failure even when average thickness is within specification. The EVOH melt is maintained at 220 °C at the die inlet, while the polyethylene layers run at 230 °C. Tie layers are selected from anhydride-modified linear low-density polyethylene grades with melt index matched to the EVOH at shear rates in the range 10–100 s⁻¹. Moisture absorption by the EVOH layer during post-extrusion cooling must be removed by drying before oxygen permeability testing, because water plasticization increases oxygen transmission. The pipe is tested after 48 hours conditioning at 23 °C and 50% RH. During long-term service at elevated water temperatures up to 70 °C, the EVOH layer remains an oxygen barrier as long as the outer polyethylene layer prevents direct contact with liquid water; any localised breach in the outer layer permits hydration of EVOH and a localised reduction in oxygen barrier.

Laminate Tube Barrier Layer Requirements for Cosmetic Actives and Solvents

Cosmetic tube laminate constructions for aggressive actives use EVOH film or extrusion-coated EVOH as a barrier to oxygen ingress and fragrance loss. In a typical laminate, the structure is polyethylene / adhesive / EVAL E105P film / adhesive / polyethylene, with the EVOH layer at 20–40 µm thickness. The EVOH layer is not in direct contact with the cosmetic formulation; the inner polyethylene layer provides moisture and chemical isolation. Fragrance retention is evaluated by gravimetric loss of marker compounds such as d-limonene and L-menthol at 40 °C over 28 days; the EVOH-containing laminate reduces permeation of these lipophilic compounds by approximately one order of magnitude relative to polyethylene-only laminated tubes under the same gravimetric capsule test. Oxygen transmission measured by ASTM D3985 at 23 °C and 50% RH is typically below 1.0 cm³/(m²·day·atm) for the laminated wall. The adhesive layers are polyurethane-based; residual isocyanate in the adhesive can react with hydroxyl groups on the EVOH surface during lamination cure, but the reaction is diffusion-limited and does not require corona treatment when the EVOH film is produced inline. Curl balance in the finished tube wall depends on symmetric polyolefin layer thicknesses, because EVOH layer expansion with humidity differs from polyethylene; asymmetrical structures show curling after storage at 60% RH or higher. Cosmetic packaging is not subject to food contact migration testing in all jurisdictions, but the laminate is tested for overall migration under EU 10/2011 when the tube is marketed for oral-care products. Solvent-containing cosmetic formulations with high ethanol content plasticize EVOH and reduce oxygen barrier; the inner polyethylene layer slows but does not completely prevent ethanol contact under long-term storage temperatures above 40 °C.

Medical device forming webs and lidding stock are manufactured on coextrusion lines producing PET / polyethylene / EVAL E105P / polyethylene / heat-sealable polymer structures. The EVAL E105P layer is set at 25 µm to 50 µm in forming webs used for trays and blister packs. Seal strength is measured according to ASTM F88 at 23 °C; typical acceptance for uncoated Tyvek lidding is ≥1.5 N/15 mm seal strength over a 15 mm seal width. Dye penetration testing according to ASTM F1929 confirms seal integrity after thermoforming and after accelerated ageing at 50 °C for 72 hours. Oxygen transmission through the forming web is measured by ASTM D3985 at 23 °C and 50% RH; values below 1.0 cm³/(m²·day·atm) are achieved when the EVOH layer remains continuous. Terminal sterilisation by gamma irradiation at doses between 25 kGy and 40 kGy can induce discolouration and chain scission in the EVOH layer; published data for E105P under these irradiation conditions is limited, and dose mapping is required before release. Ethylene oxide sterilization introduces moisture and ethylene oxide residues that can plasticize EVOH and temporarily reduce oxygen barrier; post-sterilization aeration at 35 °C for 24 hours is used to restore barrier properties. Packaging validation follows ISO 11607-1 and ISO 11607-2; the EVOH-containing forming web is evaluated as part of the complete sterile barrier system under whole package microbial barrier testing. The forming web must be protected from ambient humidity before thermoforming; storage at relative humidity above 60% for more than 48 hours without moisture barrier overwrap can cause surface defects during heating because absorbed water vaporises in the contact heater zone.