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300Module 6 of 7

Barrier Properties & Shelf-Life

Understanding O2/H2O barrier needs, coatings, and content compatibility.

6 minutes
barrier
Next: Reuse & Refill System Design
Lesson Video
Barrier Properties & Shelf-Life
Module Content

1. Executive Summary

The 7 most important insights
  1. Barrier is context‑specific. Polyolefins (PE/PP) are naturally good moisture barriers but weak oxygen barriers; PET and PA flip that pattern. EVOH offers elite O₂ barrier but loses performance as humidity rises; coatings (cross‑linked PVOH, AlOx/SiOx) or lamination architecture can stabilize it. [1, 2,3, 4]
  2. Specify test method and conditions. OTR/WVTR numbers are comparable only when standard and environmental conditions are fixed (e.g., ASTM D3985 at 23 °C/0% RH for OTR; ASTM F1927 for OTR at controlled RH; ASTM F1249 at 38 °C/90% RH for WVTR). [5, 6,7]
  3. Shelf‑life ≠ film datasheet. Real performance couples film permeation, seals/leaks, headspace, product uptake/respiration, temperature cycling, and damage (flex cracks/pinholes)—often dominating film OTR/WVTR alone. [7, 8]
  4. Regulatory simulants drive compatibility. Food type and condition of use determine simulants/time/temperature for migration (EU: A/B/C/D1/D2/E; US: food types & conditions A–H). [9, 10]
  5. Recyclability expectations are tightening.APR/CEFLEX/OPRL discourage PVDC and heavy metallization; clear AlOx/SiOx and thin EVOH/PVOH are generally compatible within thresholds—validate regionally. [11,12, 13,14]
  6. PPWR raises the bar in the EU. Design for recycling (~2030) and recycled‑at‑scale (~2035) with grades via delegated acts; barrier choices must not obstruct sortability or recycling. [15, 16]
  7. Actionable math exists. Simple ingress models plus tolerance targets let teams back‑calculate required package OTR/WVTR (and if scavengers/MAP are needed). [7]
5 recommended actions
  • Lock test standards + set‑points into RFQs: method, temperature, RH, conditioning, thickness basis. [5, 6,7]
  • Use decision trees to choose mono‑material, clear barriers (AlOx/SiOx, cross‑linked PVOH, thin EVOH) before PVDC/foil unless performance or retort demands override (document the trade‑off). [11, 12, 13]
  • Build shelf‑life ingress calculators for top SKUs and validate against pilot aging; add O₂ scavengers only when maths requires. [7,17, 18]
  • Tie artwork to sealing QA: a channel leak defeats high barrier—embed seal‑integrity testing pre/post fill. [8]
  • Maintain a live regulatory matrix (EU/US/UK simulants & conditions; PPWR/EPR/labeling; UK PPT). [9, 10,15, 19]
Key risks (12–24 months)
  • EU acts may tighten acceptance of PVDC/heavy metallization stacks. [15, 16]
  • Humidity‑sensitive barriers (EVOH/PVOH, nanocellulose) under humid routes; add protection/cross‑linking. [3, 20]
  • Claims risk: “oxygen‑free”, “moisture‑proof”, “recyclable” without substantiation against guides/testing. [11, 12, 13, 14]

2. Definitions & Concepts

  • OTR — Oxygen Transmission Rate per m² per day at specified T/RH and differential pressure (ASTM D3985 dry; F1927 controlled RH). [5, 6]
  • WVTR/MVTR — Water‑Vapour Transmission Rate (e.g., ASTM F1249 at 38 °C/90% RH). [2]
  • Permeability P = D·S (diffusivity × solubility).
  • Functional barrier — Layer limiting migration to meet food‑contact limits.
  • MAP — Modified Atmosphere Packaging.
  • O₂ scavenger — Component consuming oxygen (iron‑ based/polymeric). [17,18]
  • Food simulants (EU) — A/B/C/D1/D2/E (Tenax) per 10/2011 annexes. [9, 21, 22]
Concept map (bullets)
  • Shelf‑life target → allowable O₂/H₂O uptake → choose material/coating/format/process/additives → sealing & geometry → compliance & recyclability.

3. Standards, Regulations, and Governance

Core test standards
  • OTR — ASTM D3985 (coulometric, dry); ASTM F1927 (controlled RH); ISO 15105. [5, 6]
  • WVTR — ASTM F1249 (IR at 38 °C/90% RH); ASTM E96 (cup method, comparative). [2, 23]
Food‑contact: EU (retained in UK)
  • Framework: (EC) 1935/2004 (safety, traceability, DoC). [24]
  • GMP: (EC) 2023/2006. [25]
  • Plastics: (EU) 10/2011 — positive list, migration, simulants & conditions. [9, 26]
  • UK status: retained EU law with GB authorization process. [27, 28]
Food‑contact: US (FDA)
  • Adhesives 21 CFR 175.105 — functional barrier or trace at seams. [29]
  • Resinous/polymeric coatings 21 CFR 175.300. [30]
  • Polymer listings 21 CFR 177.*; conditions of use A–H. [10, 31]
Known changes & timelines
  • EU PPWR: staged obligations (DfR ~2030; recycled at scale ~2035) with delegated acts defining criteria/grades. [15, 16]

4. Evidence Base & Benchmarks

Method notes

Anchor values to method (D3985/F1927/F1249/E96), temperature, RH, thickness, and orientation. [5, 6, 7]

Typical barrier ranges (indicative)
Oxygen (OTR, 23 °C, 0% RH; cc/m²·day)
  • LDPE/LLDPE: ~2000–8000 (poor O₂ barrier)
  • BOPP: ~1000–2000
  • PET (OPET): ~90–150
  • PA6 (OPA): ~60–100
  • EVOH (32–44 mol% Et): < 1–10 (elite at low RH; rises with RH)
  • PVDC: ~1 or lower (very good; recyclability concerns)
  • PET/OPP AlOx/SiOx: < 1 possible on good substrate/process
  • Al foil (6–9 µm): ~0 (practical “absolute” barrier)
Moisture (WVTR, 38 °C/90% RH; g/m²·day)
  • BOPP: ~0.5–1.5 (excellent moisture barrier)
  • PET: ~10–20
  • LDPE/LLDPE: ~5–15
  • PA6: ~30–80
  • AlOx/SiOx on PET/OPP: ≤ 1 achievable
  • Al foil: ~0

Representative figures—verify against supplier spec at target thickness. [32, 4]

Humidity effects (critical)

EVOH OTR rises sharply with RH; cross‑linking PVOH or protecting EVOH in dry‑side structures mitigates. [3, 33, 34]

Why numbers conflict
  • Orientation/thickness
  • Method/conditioning (D3985 vs F1927; 0% vs high RH)
  • Substrate effects on AlOx/SiOx
  • Flex/abrasion damage post‑coating

5. Design & Production Implications

Rules of thumb
  • If moisture‑sensitive (crisps, powders): prioritise WVTR — BOPP or PE‑rich stacks; metallization or clear‑barrier as needed. [32, 35]
  • If oxygen‑sensitive (coffee, nuts, creams): drive OTR low; consider EVOH or clear‑barrier (AlOx/SiOx) plus MAP and/or scavenger. [7, 17]
  • Retort/pasteurization: pick barriers with thermal/humidity stability; PVDC and foil are high‑performance options—validate recyclability/claims. [3, 14]
  • Seals dominate: one channel leak can negate a 10× barrier gain—embed seal tests. [8]
OptionO₂ barrierH₂O barrierPrintabilityRecyclability (today)
PE/PP monoLowGood–ExcellentGoodStrong (APR‑preferred if mono)
PET/PEMedGoodExcellentMixed (design for delamination)
OPP/PELow–MedExcellentExcellentStrong (if mono‑PP)
PET AlOx/PE (clear)HighHighExcellentGenerally compatible; test per APR/DfR
EVOH in polyolefinHigh (dry)GoodGoodCompatible when thin; verify thresholds
PVDC‑coatedVery highVery highGoodProblematic (APR/OPRL caveats)
Manufacturability flags
  • EVOH placement: keep to dry‑side; shield from high RH. [3]
  • AlOx/SiOx: sensitive to substrate and flex cracking—spec abrasion/flex tests. [31]
  • US adhesives: if not behind a functional barrier, contact must be limited to trace at seams/edges (21 CFR 175.105). [29]
Supplier perspective

Provide method & set‑points, target pack‑level values (area‑scaled), aging/distribution profile, and food type & simulant plan.

6. Sustainability & Compliance Considerations

  • Favor mono‑PE/PP with clear barriers (AlOx/SiOx, thin EVOH/PVOH); avoid/minimize PVDC, heavy metallization; validate via APR/OPRL. [11, 13, 14]
  • EU PPWR’s DfR and Recycled‑at‑Scale will penalize barrier stacks that block sortability or contaminate the stream. [15, 16]
  • UK PPT: tax applies if < 30% recycled content; ensure food‑contact legality. [19]
  • Ground claims in regional definitions and qualified test results.

7. Workflow & Tooling (ready to adapt)

Checklists
  • Print‑ready: dieline area calc; barrier callouts with method/conditions beside each number; seal geometry notes.
  • Compliance: EU/US/UK simulant matrix; DoC; supplier CoCs; migration report (time/temp); PPT/EPR tracking. [9, 10, 19]
  • Recyclability: APR/CEFLEX/OPRL self‑audit; barrier/coating compatibility notes. [11, 12, 14]
Decision trees
  • Label stock/adhesive: substrate → stream → wash‑off/bleed risk → barrier interaction → label area thresholds per APR/OPRL. [11, 14]
  • Print process by run‑length/substrate: solvent vs water‑based vs EB/UV; note interaction with barrier coats (e.g., cross‑linked PVOH).
Calculator blueprints
  1. O₂ ingress → time‑to‑limit — Inputs: OTR (cc/m²·day at method), area A (m²), outside O₂ partial pressure Δp (≈0.21 atm vs internal), initial headspace O₂ O₂₀ (cc), acceptable in‑pack O₂ threshold O₂ₜₕ (cc), correction factors for T/RH. Ingress rate ≈ OTR × A × (Δp/1 atm). Time ≈ (O₂ₜₕ − O₂₀ − product consumption) / ingress. Use F1927 for humid cases or conservatively scale D3985. [6, 7]
  2. Moisture ingress — Mass H₂O(t) ≈ WVTR × A × t × driving‑force factor (if not 90→0% RH). Tie to aw thresholds. [2]
  3. Scavenger sizing — Required capacity ≥ (residual O₂ + ingress over shelf‑life); consider RH activation. [17, 36]
Template RFQ fields

Method/conditions per test; target OTR/WVTR; seal spec; migration plan (simulant/time/temp); recyclability target & guide; PPWR risk; PPT data.

8. Category‑Specific Guidance

Beauty (oils, actives, fragrance)
  • Drivers: oxygen (rancidity), fragrance loss (sorption), water ingress.
  • Approach: PET/EVOH/PE or PP mono with AlOx/SiOx; validate SMLs via simulants (C, D1/D2). [9]
Food (coffee, nuts, snacks)
  • Coffee: very low OTR; manage CO₂ release; one‑way valve; nitrogen flush; scavenger sized from model. [7, 17, 37]
  • Snacks/crisps: WVTR controls crunch; metallized OPP or clear‑barrier PP often doubles theoretical shelf‑life vs paper/glassine. [35]
Beverage (non‑carbonated, beer in PET)
  • Drivers: O₂ ingress through wall/closure; options include scavenger‑enhanced PET, multilayer PET/EVOH, liner/closure upgrades. Validate at storage temps.

9. Case Studies (Problem → Approach → Result)

1) Humid route EVOH pouch
Problem: OTR drift during monsoon distribution.
Approach: EVOH moved to dry‑side; add AlOx‑PET outer; re‑spec at ASTM F1927 humidity. [3, 6, 4]
Result: Stable OTR across 75–90% RH; label recyclable with caveats per APR.
2) Coffee re‑launch
Problem: Flat flavour after 8 weeks.
Approach: PET/AlOx/PE + valve; nitrogen flush + scavenger capacity from ingress model. [7, 17, 37]
Result: Acceptability > 6–9 months; QC via headspace O₂.
3) Snack moisture creep
Problem: Loss of crunch in summer promos.
Approach: Switch to metallized OPP + tighter seal spec; WVTR halved; shelf‑life ~2× in accelerated tests. [35]

10. Common Pitfalls & Red Flags

  1. Quoting film OTR without method/T/RH. [5, 6]
  2. Ignoring humidity on EVOH/PVOH barriers. [3, 34]
  3. Using PVDC/heavy metallization without a recyclability strategy. [11, 14]
  4. Seals not validated—channel leaks erase barrier gains. [8]
  5. Wrong simulant for ethanol/fat phases in migration tests. [9, 10]
  6. Assuming vendor OTR/WVTR equals pack performance (area, seams, closures matter). [7]

References

  1. Measurlabs — WVTR/OTR overview
  2. ASTM F1249 — WVTR (scope)
  3. PFFC — EVOH barrier vs humidity
  4. SVC — AlOx coatings on films
  5. ASTM D3985 — OTR (scope)
  6. AMETEK — D3985 vs F1927
  7. AMETEK — OTR and shelf‑life
  8. Food Contact Materials — EP study
  9. EU 10/2011 (Annexes — simulants)
  10. FDA — Food types & conditions of use
  11. APR — PP flexible guidance
  12. OPRL — How to use labels
  13. APR/RecyClass alignment note
  14. APR Design® Guide PDF
  15. ECOS — PPWR analysis
  16. EUROPEN — PPWR survival guide
  17. PMC — Oxygen absorbers review
  18. Clemson — Shelf‑life model thesis
  19. GOV.UK — Plastic Packaging Tax
  20. MDPI — Nanocellulose barrier at high RH
  21. PlasticsEurope — 10/2011 explanatory
  22. Smithers — Migration simulants
  23. E96 vs F1249 comparator
  24. TAPPI — Clear barriers & productivity
  25. Poly Print — WVTR by material
  26. RSC — Cross‑linking improves PVOH
  27. RIT — Temp/RH effects on barrier
  28. SVC — Snack barrier (Frito‑Lay)
  29. Scavenger kinetics vs RH/T
  30. U. Guelph — Degassing valve behavior
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