PVDC Coating vs EVOH vs Metallized Film: High-Barrier Packaging Material Selection Guide

Overview #

The specification parameter that most procurement teams get wrong when selecting high-barrier packaging films is oxygen transmission rate — not tensile strength, not seal strength, and not even moisture vapor transmission rate. OTR determines shelf life. Everything else is secondary. When sourcing PVDC-coated film, EVOH laminate, or metallized film from Chinese converters, the first document to request is not the product datasheet — it is the OTR test report with method, conditions, and lot number. A datasheet value is a design target. A lot-specific OTR report is evidence.

The three barrier technologies covered here — PVDC coating, EVOH co-extrusion, and vacuum metallization — are not interchangeable. Each has a specific performance envelope, a specific failure mode under Chinese supply chain conditions, and a specific set of incoming inspection parameters that determine whether the material will perform in your application or fail at the filler.

Barrier Performance Specifications: What the Numbers Actually Mean #

The core performance metric for any high-barrier film is OTR, measured in cc/m²·day·atm, and MVTR (moisture vapor transmission rate), measured in g/m²·day. These two values define the application window. Everything else — haze, gloss, seal range — is secondary to barrier integrity.

PVDC coating (polyvinylidene chloride, typically applied as an aqueous emulsion at 3–8 g/m² dry coat weight) delivers OTR in the range of 1–5 cc/m²·day at 23°C/0% RH and MVTR below 2 g/m²·day at 38°C/90% RH when coat weight is controlled. The critical variable is coat weight uniformity across the web — not the average coat weight. A coating that averages 5 g/m² but varies ±2 g/m² across the web will produce barrier failures at the thin zones. In our supplier qualification program, we require coat weight CV (coefficient of variation) below 8% across the full web width before approving a PVDC-coated substrate for production volume.

EVOH co-extrusion (ethylene vinyl alcohol copolymer, typically 3–12 mol% ethylene content for packaging grades) achieves OTR values below 0.5 cc/m²·day at 23°C/0% RH — significantly better than PVDC in dry conditions. The critical limitation is humidity sensitivity: at 85% RH, EVOH OTR can increase by a factor of 10–50× depending on ethylene content. This is not a defect — it is a fundamental material property. EVOH must be sandwiched between moisture-barrier layers (typically PE or PP) in a co-extruded structure to maintain barrier performance in humid environments. Buyers who specify EVOH without specifying the full laminate structure are specifying the wrong thing.

Metallized film (aluminum vacuum-deposited on PET, OPP, or CPP substrate, typically at optical density 2.0–3.5) achieves OTR below 1 cc/m²·day and MVTR below 0.5 g/m²·day when optical density is maintained. The failure mode is flex cracking — aluminum layer fracture during converting, handling, or filling. A metallized film that passes OTR at goods receipt can fail after 500 flex cycles on a VFFS machine. ASTM International F1249 and F2622 are the standard test methods for MVTR and OTR respectively; any COA that does not cite the test method and conditions is not a valid barrier specification document.

*EVOH MVTR in unprotected form; in full PE/EVOH/PE laminate, effective MVTR approaches <1.0 g/m²·day.

Most Western buyers do not realize that SAC China Standards GB/T 1038 (gas permeability) and GB/T 26253 (PVDC-coated film) allow test conditions that differ from ISO Standards 15105-2 and ISO 15106-3. A Chinese supplier reporting OTR “per GB/T 1038” at 23°C/50% RH is not reporting the same number as a supplier reporting per ISO 15105-2 at 23°C/0% RH. The values are not directly comparable. This is the single most common specification mismatch we see in incoming inspection documentation from Chinese converters.

For related substrate and laminate categories, see barrier films and material substrates and specialty coatings for coating-specific qualification criteria.

Application-Driven Selection: Matching Technology to End-Use Requirements #

Selecting barrier technology based on OTR alone is a procurement mistake. The correct selection sequence is: (1) define the required shelf life and headspace gas composition, (2) calculate the required OTR and MVTR for that shelf life, (3) identify which barrier technology achieves those values under the actual use conditions — including temperature, humidity, and mechanical stress — and (4) verify that the Chinese converter can produce that structure with lot-to-lot consistency.

Most procurement teams skip step 4. That is where the sourcing risk lives.

Retort and high-temperature applications (>100°C): PVDC coating degrades above 150°C and is not suitable for retort sterilization above 121°C. EVOH in a co-extruded retort structure (typically PA/EVOH/PP or PET/EVOH/PP) maintains barrier integrity through 121°C/30-minute retort cycles. Metallized film is not retort-compatible — the aluminum layer delaminates under steam pressure. If your application involves retort sterilization, EVOH co-extrusion is the only viable option among these three technologies.

Modified atmosphere packaging (MAP) and vacuum packaging: For MAP applications requiring OTR below 1 cc/m²·day, all three technologies are technically viable in dry conditions. The differentiator is the filling environment. If your MAP line operates above 60% RH (common in fresh produce and dairy facilities), EVOH in an unprotected structure will underperform. PVDC-coated film or metallized film is more appropriate for high-humidity filling environments.

Pharmaceutical blister packaging: ISO Standards 15223 and the FDA Guidelines 21 CFR 211.94 govern packaging material requirements for pharmaceutical applications. PVDC-coated PVC (cold-form or thermoform) is the dominant technology for pharmaceutical blister, with PVDC coat weights of 40–120 g/m² for ultra-high barrier applications. Standard 40 g/m² PVDC/PVC achieves OTR below 0.5 cc/m²·day; 90 g/m² PVDC/PVC achieves below 0.1 cc/m²·day. These are not interchangeable grades — specifying “PVDC blister film” without specifying coat weight is an incomplete specification.

We always request three consecutive batch COAs before recommending qualification of a Chinese converter for pharmaceutical-grade PVDC blister film. Lot-to-lot coat weight variation is the primary failure mode, and it is invisible without incoming testing. A single approved sample tells you nothing about production consistency.

Flexible retort pouches and stand-up pouches: The dominant structure in China for retort pouches is PET/AL foil/CPP or PET/AL foil/PA/CPP. Aluminum foil (not metallized film) is used here — the barrier is fundamentally different. Metallized film OTR of <1 cc/m²·day is adequate for many ambient shelf-life applications but is not equivalent to aluminum foil barrier (<0.01 cc/m²·day). Buyers who substitute metallized film for foil laminate in retort applications will experience barrier failure.

Compliance, Recyclability, and Regulatory Constraints #

PVDC contains chlorine. Under ECHA REACH and the EU Packaging and Packaging Waste Regulation (PPWR), PVDC-coated films face increasing regulatory pressure in European markets due to chlorine content and recyclability limitations. PVDC-coated films are not compatible with PET or PP recycling streams — they contaminate the melt. If your end market is the EU and your customer has recyclability commitments under the PPWR 2030 targets, PVDC coating is a technology with a defined regulatory risk horizon.

EVOH-based mono-material structures (all-PE or all-PP with EVOH barrier layer) are the primary technical response to recyclability requirements. ISO Standards 18604 and the RecyClass protocol define recyclability criteria for flexible packaging. A PE/EVOH/PE structure with EVOH layer below 5% by weight can qualify as recyclable under RecyClass guidelines — but only if the EVOH layer thickness is controlled within specification. Chinese converters producing “recyclable barrier film” without specifying EVOH layer thickness and total structure composition are not providing a verifiable recyclability claim.

Metallized film recyclability depends on substrate: metallized OPP is not recyclable in standard PP streams due to the aluminum layer. Metallized PET faces similar constraints. The “recyclable metallized film” claims appearing in Chinese converter marketing materials typically refer to wash-off metallization or ultra-thin aluminum deposition — technologies that require specific verification, not acceptance at face value.

For REACH compliance documentation, require a full substance declaration per ECHA REACH Article 33 for any PVDC-coated film. Vinylidene chloride monomer (VCM) residual content should be below 1 mg/kg in the finished film for food contact applications — this is a parameter that must appear on the food contact compliance declaration, not just the material safety datasheet.

Practical Guidance for Buyers #

When sourcing high-barrier film from Chinese converters, the first specification to request is not the product datasheet — it is the OTR test report with test method, conditions (temperature and RH), and lot number. A datasheet OTR value is a design target; a lot-specific test report is evidence of actual production performance.

The sourcing mistake we see most often is specifying OTR without specifying test conditions. A Chinese converter reporting OTR at 23°C/50% RH will show a significantly better number than the same film tested at 23°C/0% RH for PVDC, or at 38°C/90% RH for EVOH. These are not equivalent. Specify the test method — ASTM International F2622 for OTR, F1249 for MVTR — and the exact conditions in your purchase specification.

Before committing to volume order, require the following from any Chinese converter:

1. OTR and MVTR test reports — minimum 3 consecutive production lots, same test method and conditions, with lot numbers traceable to COA
2. Coat weight or layer thickness data (PVDC: g/m² with CV%; EVOH: µm layer thickness in co-extrusion structure)
3. Optical density report for metallized film (target OD 2.5–3.0 for standard barrier; OD 3.0–3.5 for high barrier), with flex crack OTR retention after 500 flex cycles per ASTM International F392
4. Food contact compliance declaration per applicable regulation (EU 10/2011, FDA 21 CFR, or GB 9685) with VCM residual <1 mg/kg for PVDC grades
5. Lot-to-lot consistency data — six months of production OTR data, not just the most recent lot
6. Recyclability documentation if EU market: RecyClass protocol assessment or equivalent, with EVOH layer % by weight
7. GB/T vs ISO test method declaration — confirm which standard was used and request ISO-equivalent data if GB/T was the primary test method

The test that most buyers skip — and that catches the most failures — is incoming OTR spot-testing on production lots after initial qualification. Initial sample approval is not a substitute for ongoing incoming inspection.

Frequently Asked Questions #

Q1: What is the most important specification to verify on a COA for high-barrier film from a Chinese supplier?

A: OTR with test method and conditions. A COA that lists OTR without specifying whether it was tested per ASTM F2622 or GB/T 1038, and at what temperature and RH, is not a verifiable specification.

Q2: When should I choose EVOH over PVDC coating for a flexible packaging application?

A: Choose EVOH when you need OTR below 0.5 cc/m²·day in dry conditions, when the application involves retort sterilization above 100°C, or when your end market requires recyclable packaging under EU PPWR targets. Choose PVDC when the filling environment exceeds 60% RH and a full co-extruded laminate structure is not feasible — PVDC’s barrier is less humidity-sensitive than unprotected EVOH. The comparison table above gives the full performance envelope for both technologies.

Q3: What is the most common quality failure when sourcing metallized film from China?

A: Flex cracking after converting. This is where most sourcing decisions go wrong. A metallized film can pass OTR at goods receipt and fail after 500 flex cycles on a VFFS machine — the aluminum layer fractures and barrier is lost. The threshold to require is OTR retention above 80% of initial value after 500 flex cycles per ASTM International F392. Most Chinese converters do not include this test in their standard COA unless you specifically require it.

Q4: What compliance documentation should I require for PVDC-coated film destined for EU food contact applications?

A: Require a food contact compliance declaration per EU Regulation 10/2011 with explicit confirmation that vinylidene chloride monomer (VCM) residual is below 1 mg/kg in the finished film. Also require a full substance declaration per ECHA REACH Article 33. A material safety datasheet alone is not sufficient for EU food contact compliance.

Q5: Is “recyclable barrier film” from a Chinese converter a reliable claim without third-party verification?

A: No. Require the RecyClass protocol assessment or equivalent documentation showing EVOH layer below 5% by weight in the total structure. The claim without documentation is marketing, not specification.

Published by sinoraw.com Technical Team | Request a sourcing consultation