What is the difference between PVC and PVDC film?

PVC vs PVDC Film: The Core Difference at a Glance

PVC (Polyvinyl Chloride) and PVDC (Polyvinylidene Chloride) are both chlorine-containing polymer films, but they serve very different purposes in packaging. PVC is a general-purpose film valued for its clarity and cost-effectiveness, while PVDC is specifically engineered for superior barrier performance against moisture, oxygen, and odors. If your application demands extended shelf life or strict protection from environmental factors, PVDC outperforms PVC by a significant margin.

In practical terms: PVC is widely used in blister packaging, shrink wrap, and medical device packaging; PVDC is the preferred choice in food packaging, pharmaceutical blisters, and any application where gas and moisture transmission must be minimized.

Chemical Structure and Composition Differences

Although both materials contain chlorine atoms, their molecular structures differ fundamentally:

• PVC is built from vinyl chloride monomers. Its structure includes only one chlorine atom per repeating unit, which gives it flexibility and processability but moderate barrier properties.
• PVDC is derived from vinylidene chloride monomers, featuring two chlorine atoms per repeating unit. This symmetrical, tightly packed molecular arrangement results in a highly crystalline structure that dramatically reduces permeability.

The higher chlorine density and crystallinity of PVDC are the primary reasons it delivers far better barrier performance than PVC.

Barrier Performance: A Direct Comparison

Barrier performance is the most critical difference between the two films. The table below summarizes key metrics:

For applications requiring an oxygen transmission rate below 1 cc/m²/day — such as meat packaging or sensitive pharmaceutical products — PVDC is often the only viable single-material option without resorting to multi-layer laminates.

What Is PVDC Coated Film and How Does It Work?

Rather than using a standalone PVDC film, many packaging solutions apply a thin PVDC coating onto a base substrate such as OPP, PET, or nylon. This is known as PVDC coated film. The coating is typically applied at thicknesses ranging from 2 to 8 gsm (grams per square meter), depending on the required barrier level.

The working principle is straightforward: the highly crystalline PVDC layer acts as a molecular barrier, blocking the passage of oxygen, water vapor, and aromatic compounds. Even a coating as thin as 3 gsm can reduce oxygen transmission by over 90% compared to uncoated base films.

Advantages of PVDC Coated Film Over Pure PVDC Film

• Lower cost: Using a thin coating rather than a full PVDC film significantly reduces material costs while maintaining strong barrier performance.
• Design flexibility: The base substrate can be chosen to optimize other properties — such as stiffness, heat resistance, or printability — independently of the barrier layer.
• Excellent machinability: PVDC coated films run well on standard FFS (form-fill-seal) and thermoforming equipment without special handling requirements.
• Printability: The coated surface accepts gravure and flexographic inks well, making it suitable for branded flexible packaging.

Typical Applications: Where Each Film Is Used

PVC Film Applications

• Standard blister packaging for non-sensitive tablets and capsules
• Shrink wrapping for retail products
• Cling films for food service use
• Medical device packaging where moisture barrier is not critical
• Stationery and document protection sleeves

PVDC Film and PVDC Coated Film Applications

• Pharmaceutical blister packaging for moisture-sensitive drugs (e.g., effervescent tablets, hygroscopic capsules)
• Vacuum-packed meat, cheese, and processed foods requiring extended shelf life
• Flexible packaging for coffee, snacks, and instant noodles where aroma retention is important
• Retort pouches requiring both heat resistance and high barrier
• Agricultural and industrial packaging where chemical resistance is required

Thermal and Mechanical Properties

Beyond barrier performance, the two films also differ meaningfully in their physical behavior during processing:

• Processing temperature: PVC can be thermoformed and sealed at relatively low temperatures (around 120–160°C). PVDC is more thermally sensitive and requires careful temperature control to avoid degradation, typically processed below 180°C.
• Flexibility: PVC with plasticizers is highly flexible; unplasticized PVC is rigid. PVDC on its own is stiffer but PVDC coated films inherit the flexibility of their substrate.
• Tensile strength: Both materials offer acceptable tensile strength for most packaging uses; the substrate choice in coated films provides additional mechanical tuning options.
• Heat sealing: PVDC coated films seal reliably at moderate temperatures and form strong, consistent seals — a key advantage for high-speed packaging lines.

Environmental and Regulatory Considerations

Both PVC and PVDC contain chlorine, which raises end-of-life concerns, as incineration can generate hydrogen chloride gas. This has led to increasing regulatory scrutiny in some markets:

• Several European countries have restrictions or guidelines around PVC use in food-contact packaging, encouraging substitution with chlorine-free alternatives.
• PVDC faces similar environmental criticism, and some packaging converters are actively exploring alternatives such as EVOH or acrylic-based barrier coatings for sustainability goals.
• Despite this, both films remain widely approved under major food safety and pharmaceutical regulations, including FDA and EU food contact material standards, when formulated correctly.
• For pharmaceutical applications specifically, PVDC continues to dominate due to its unmatched combination of moisture barrier, regulatory acceptance, and thermoformability.

How to Choose Between PVC, PVDC, and PVDC Coated Film

The right choice depends on your specific packaging requirements. Use the following decision guide:

1. If cost is the primary driver and barrier requirements are low → Choose standard PVC film.
2. If you need maximum moisture and oxygen barrier in a single-layer film → Choose standalone PVDC film (common in high-end pharmaceutical blisters).
3. If you need a balance of barrier performance, printability, and cost efficiency → Choose PVDC coated film on an OPP or PET substrate.
4. If sustainability is a key criterion and barrier is still needed → Evaluate EVOH-based alternatives or acrylic barrier coatings.

For most flexible food and mid-range pharmaceutical packaging applications, PVDC coated film offers the best overall value — combining meaningful barrier improvement with manageable cost and excellent processability.

FAQ

Q1: Is PVDC film the same as Saran wrap?

Originally, yes — early cling wraps used PVDC for its superior barrier. Most modern consumer cling films have switched to LLDPE or PVC due to cost and environmental concerns, though industrial PVDC films remain widely used.

Q2: Can PVDC coated film be used in retort packaging?

Yes, when applied onto heat-resistant substrates like PET or nylon, PVDC coated films can withstand retort temperatures up to around 121°C, making them suitable for sterilized food pouches.

Q3: How thick is a typical PVDC coating?

Standard coatings range from 2 to 8 gsm. Higher coating weights deliver better barrier performance but increase cost. Most food packaging applications use 3–5 gsm as a practical balance point.

Q4: Is PVC safer than PVDC for food contact?

Both can be formulated to comply with food contact regulations. The safety concern with PVC is mainly around plasticizer migration in flexible grades. PVDC does not require plasticizers, which is an advantage in food and pharmaceutical contact applications.

Q5: What substrates are most commonly used for PVDC coated film?

The most common base substrates are OPP (biaxially oriented polypropylene), PET (polyester), and nylon (PA). OPP-based PVDC coated film is the most widely used in snack and confectionery packaging due to its cost-effectiveness and clarity.