EVOH for Cosmetic Plastic Tubes & Hoses

EVOH barrier layers in cosmetic tubes and hoses are specified when oxygen-sensitive actives, fragrance partitioning, or flavour retention demand an oxygen ingress barrier beyond that of polyolefin-only structures. The following application scenarios are limited to documented downstream manufacturing configurations and do not include pharmaceutical parenteral or medical device uses where separate ISO 10993 or pharmacopoeia requirements apply.

In a five-layer PE/tie/EVOH/tie/PE tube body for a 0.5 wt% retinol facial cream, the EVOH layer is specified at 12–15 µm within a 300–350 µm wall, equivalent to 3.8–4.6 wt% of the tube body compound. Oxygen ingress through the sidewall is controlled by a 32 mol% ethylene EVOH; oxygen transmission of the tube body is assessed according to ASTM D3985-17 at 23 °C and 0 % RH, with typical values between 0.02 cm³/(m²·day·atm) and 0.08 cm³/(m²·day·atm). Migration of retinol into the inner LDPE layer is a separate failure mode and is not directly addressed by oxygen transmission testing; package compatibility studies under ISO 22716:2007 and Annex I of EU Regulation (EC) No 1223/2009 record batch-specific inner-layer extractables data before filling.

On production-scale five-extruder lines, the outer PE extruder is a 45 mm 24:1 L/D single-screw, the EVOH extruder is a 35 mm 28:1 L/D barrier screw, and the inner PE extruder is a 45 mm 24:1 L/D single-screw. The EVOH melt temperature is held at 200–230 °C; above 235 °C amber gel particles appear after 8–10 min residence time in the adapter and die, generating visible specks in the tube wall and forcing a purge with LDPE at 210 °C. Tie layers are maleic anhydride-grafted polyethylene at 8–15 µm each, applied through two separate extruders or through a feedblock with tie-layer split. The spiral mandrel die operates at 20–30 bar melt pressure. The extruded sleeve is cut, the shoulder is injection molded from cosmetic-contact LDPE, and tubes are filled under vacuum. Terminal formats are 30 mL and 50 mL tubes for retinol creams, ascorbic acid serums, and tocopherol/ubiquinone anti-aging emulsions.

The limiting operational boundary is moisture sensitivity of EVOH. At 65 % RH, oxygen transmission of the barrier layer increases to 0.5–1.2 cm³·mm/(m²·day·atm) when conditioned and tested per ASTM D3985-17 at 65 % RH. The outer LDPE and tie layers reduce relative humidity at the EVOH surface to 45–55 % RH when ambient humidity is 65 % RH; at ambient 90 % RH, the EVOH surface approaches 70–75 % RH and oxygen barrier deteriorates by a factor of 10–20. Tubes intended for bathroom storage therefore require an outer HDPE cap or moisture shielding layer, and pre-drying of EVOH resin to < 0.05 % moisture with a desiccant dryer at 80–90 °C is mandatory before extrusion.

What Limits Fragrance Retention in Hair Colour Developer Hoses Under Intermittent Squeeze?

Alkaline pH 9.5–10.5 hair colour developer in a 250 mL hose requires an inner LDPE or LLDPE layer of 80–120 µm to prevent direct contact between the developer and the EVOH barrier. Fragrance partitioning into the polyolefin inner layer is controlled by the lipophilic character of the fragrance compounds; EVOH does not reverse this partitioning, but it reduces oxygen-driven oxidation of fragrance aldehydes and terpenes during shelf life. The EVOH layer is inserted as the third of seven layers at 10–20 µm, representing 4.2–5.8 % of the total hose wall and 3.5–5.0 wt% of the multilayer compound. Oxygen transmission of the hose wall is tested according to ASTM D3985-17 at 23 °C, 0 % RH; hoses with 10 µm EVOH show 0.05–0.15 cm³/(m²·day·atm), while 20 µm EVOH hoses show 0.02–0.06 cm³/(m²·day·atm).

The seven-layer hose is coextruded on a line with a 50 mm 30:1 L/D outer HDPE extruder, a 30 mm 30:1 L/D EVOH extruder with barrier-flight screw, and tie-layer extruders for maleic anhydride-grafted PE at 8–12 µm. Melt pressure before the feedblock is 180–220 bar; the EVOH residence time is held below 20 min because EVOH forms crosslinked gel particles that cannot be removed without die cleaning after extended heat history. Shutdown purges use LDPE at 210 °C. The hose is corrugated in-line, cut to length, and assembled with injection-moulded taper and dispensing brush tips. Regulatory documentation references REACH Regulation (EC) No 1907/2006 Annex XVII restrictions for phthalates and heavy metals in plastic packaging, while the cosmetic product safety report follows Annex I of EU Regulation (EC) No 1223/2009.

Intermittent squeeze cycling in hair colour developer hoses produces flexural fatigue at the shoulder-to-hose junction. The EVOH layer is not the primary crack initiation site when tie-layer adhesion is above 2.5 N/15 mm as measured by ASTM F904-16; below that adhesion value, delamination at the tie/EVOH interface creates pinholes after 5,000–10,000 cycles. Final assembled formats are 100 mL and 250 mL developer tubes with nozzle caps and brush tips, filled under nitrogen to reduce oxidative damage to fragrance aldehydes.

A three-layer PE/tie/EVOH dispensing hose for a 100 mL continuous-spray sunscreen is specified with outer diameter 5.0 mm and wall thickness 1.0 mm. The EVOH core is 25–35 µm, corresponding to 5.0–6.5 wt% of the hose compound; this concentration is higher than in squeeze tubes because the small internal volume and high surface-area-to-volume ratio increase oxygen ingress per unit product. The UV filter package includes avobenzone and octocrylene, which degrade through triplet-state and singlet-oxygen pathways; the package cannot prevent photochemical degradation if the hose is transparent, but opaque white PE outer layers block visible and UV light while the EVOH core reduces oxygen ingress. Oxygen barrier is tested at 23 °C, 0 % RH according to ASTM D3985-17; whole-hose values for a 30 µm EVOH layer are 0.01–0.04 cm³/(m²·day·atm).

The hose is extruded on a 25 mm 28:1 L/D EVOH single-screw with a mixing section and a 35 mm 24:1 L/D PE extruder. EVOH melt temperature is maintained at 205–225 °C; outer PE melt temperature above 250 °C can overheat the EVOH in the die and produce interfacial roughness. Vacuum sizing with chilled water at 10–15 °C sets the outer diameter before haul-off. The hose is cut and welded to pump components; final formats are 100 mL and 150 mL continuous-spray bottles filled under nitrogen. Packaging documentation references REACH Regulation (EC) No 1907/2006 and ISO 22716:2007; UV filter stability testing may follow ISO 24443:2012 for simulated SPF after storage, but that method measures product performance and not packaging barrier.

Toothpaste Flavour Retention Requires Thinner EVOH Layers and Shoulder Geometry Control

A 75 mL toothpaste tube body is coextruded as a five-layer PE/tie/EVOH/tie/PE sleeve with total wall thickness 250–300 µm. The EVOH barrier layer is 8–12 µm, representing 3.0–4.2 % of the tube wall and 2.8–3.8 wt% of the body compound. This is lower than that used for retinol creams because toothpaste flavour compounds—menthol, eucalyptol, anethole—have higher permissible oxygen ingress limits than retinoids. Flavour retention is not defined by a single ISO method; filled-tube studies use gas chromatographic headspace analysis after 6 months at 40 °C, while oxygen ingress is measured by ASTM D3985-17 at 23 °C, 0 % RH. Compliance references ISO 11609:2017 for dentifrice requirements and ISO 22716:2007 for packaging material acceptance records.

The line configuration uses a 35 mm 24:1 L/D EVOH extruder at 195–220 °C and a 50 mm 28:1 L/D PE extruder. The shoulder is injection molded separately from LDPE without EVOH, creating a barrier discontinuity that is the dominant oxygen ingress path in the finished tube; whole-tube ASTM D3985-17 testing on filled tubes shows shoulder oxygen ingress 3–5 times higher per unit area than through the sidewall. To offset this, the shoulder wall is thickened to 1.0–1.4 mm and sealed with an aluminium-free EVOH-containing laminate membrane over the orifice. Terminal configurations are 75 mL and 100 mL opaque toothpaste tubes for anti-cavity and whitening pastes.

When EVOH Loading Approaches 5% in Recyclable Polyethylene Cosmetic Tubes

For a recyclable polyethylene tube, EVOH content is capped below 5 wt% of the whole tube, including shoulder and cap, because EU Directive 94/62/EC packaging waste assessments and RecyClass PE film guidelines treat higher EVOH concentrations as incompatible with polyethylene recycling streams. The cap translates to an EVOH layer of 12–18 µm in a 300 µm tube body with a 1.0–1.2 mm HDPE shoulder. At 4.8 wt% loading, EVOH must be present as discrete lamellae; large EVOH domains create gel-like defects in recycled HDPE film at 0.1–0.3 mm thickness. Oxygen barrier of the tube body is measured according to ASTM D3985-17 at 23 °C, 0 % RH; with 15 µm EVOH, values are 0.03–0.08 cm³/(m²·day·atm). This structure is not specified for oxygen-sensitive retinoids in high-humidity bathroom storage because the thinner moisture shielding layers weaken EVOH barrier retention.

Production uses five-layer coextrusion with a 45 mm 24:1 L/D PE screw and a 30 mm 28:1 L/D EVOH screw. The recyclability claim is conditional on local sorting and washing infrastructure; published data for three-dimensional tube recyclability under RecyClass testing is limited because RecyClass protocols primarily evaluate flat films. Completed tube configurations are 50 mL and 150 mL body lotion tubes sold in markets where packaging recyclability is a retail listing criterion.

Airless Pump Hose Wall Thickness and Oxygen Ingress Rate Correlation

The airless pump hose for a water-free 10 wt% ascorbic acid serum is specified with inner diameter 3.0 mm and wall thickness 0.6–0.8 mm. The five-layer PE/tie/EVOH/tie/PE hose uses an EVOH layer of 20–30 µm, corresponding to 5.5–7.0 wt% of the hose compound because the small internal volume and high surface-area-to-volume ratio require a thicker barrier layer than standard squeeze tubes. Oxygen barrier is measured at 23 °C, 50 % RH according to ASTM D3985-17; the hose wall achieves 0.04–0.10 cm³/(m²·day·atm). The higher EVOH loading increases flexural modulus from 120–160 MPa at 3 wt% EVOH to 180–240 MPa at 7 wt%, measured by ISO 178:2019. Cyclic bending beyond 50,000 cycles at the pump connector can initiate EVOH layer fatigue cracks; published data for this specific configuration is limited and must be validated with the final pump geometry.

The hose is extruded on a 20 mm 30:1 L/D single-screw barrier EVOH extruder with melt pump and a 30 mm 24:1 L/D LLDPE extruder. The die is a spiral mandrel with annular gap 0.3 mm; melt temperature for EVOH is 200–225 °C, melt pressure 150–200 bar. Because of the small inner diameter, vacuum calibration is replaced by pressure sizing at 0.4–0.8 bar. The finished hose is cut to 60–100 mm and assembled with a metal-free spring and piston. Final assembled formats are 30 mL and 50 mL airless pump bottles for anhydrous vitamin C serums. Packaging documentation references ISO 22715:2006 and ISO 22716:2007.