1. Introduction to Plastic Film in Food Packaging

Plastic film has become the backbone of modern food packaging. From the thin wrap protecting a tray of fresh meat to the multi-layer lidding seal on a ready-meal container, plastic films perform a broad range of critical functions: they act as moisture barriers, oxygen shields, tamper indicators, and aesthetic carriers—all simultaneously.

According to the Flexible Packaging Association, flexible plastic films account for more than 19% of all packaging materials sold globally, with food packaging representing the largest single application segment. Within that segment, barrier shrink film and lidding film technologies have seen the fastest growth, driven by demand for extended shelf life, retail display quality, and cold-chain compatibility.

Understanding the technical architecture of these films—their polymer compositions, layer structures, sealing properties, and barrier ratings—is essential for food manufacturers, packaging engineers, and procurement professionals who specify materials at scale.

2. Types of Plastic Films Used in Food Packaging

Plastic films used in food packaging are rarely single-layer monolithic sheets. Most commercial food films are co-extruded multi-layer structures engineered to combine the best properties of several polymers into one coherent film. The primary polymer families include:

Polyolefin Films (POF)

Polyolefin shrink films—typically based on polyethylene (PE) and polypropylene (PP) blends—are the most widely used flexible films in food retail. They are valued for their optical clarity, low seal initiation temperature, and broad heat-shrink range (typically 65°C–130°C). POF films are FDA-compliant and food-safe across all standard applications.

Polyamide (PA / Nylon) Films

Nylon-based films offer outstanding puncture resistance and mechanical toughness, making them the material of choice for bone-in meat packaging and sharp-edged products. PA films also provide moderate oxygen barrier performance and excellent thermoformability.

Ethylene Vinyl Alcohol (EVOH)

EVOH is the gold standard for passive oxygen barrier performance in flexible packaging. At a relative humidity below 75%, EVOH can achieve oxygen transmission rates (OTR) as low as 0.01–0.05 cc/m²/day/atm—roughly 10,000 times better than standard PE. EVOH is always used as an inner core layer, sandwiched between moisture-resistant polyolefin layers, because its barrier performance degrades at high humidity.

Polyvinylidene Chloride (PVDC)

PVDC offers simultaneous barriers against oxygen, water vapor, and aroma compounds. It is commonly used as a coating or co-extrusion layer in meat and cheese packaging. While highly effective, PVDC's chlorine content has attracted regulatory and environmental scrutiny in several markets, driving a shift toward EVOH-based alternatives in Europe and North America.

Oriented Polypropylene (OPP) and Biaxially Oriented Films (BOPP / BOPA)

Orientation—either mono-axial or biaxial stretching—significantly enhances tensile strength, optical clarity, and moisture vapor barrier. BOPP films are widely used in snack, confectionery, and dry food packaging. BOPA films combine the mechanical strength of nylon with the dimensional stability gained from biaxial orientation.

3. Barrier Properties: The Core Performance Metric

In food packaging science, barrier performance refers to a film's resistance to the transmission of gases, vapors, and liquids across its surface. The two most critical transmission metrics are:

Oxygen Transmission Rate (OTR) — measured in cc/m²/24h/atm at specified temperature and relative humidity (commonly 23°C / 0% or 50% RH)

Water Vapor Transmission Rate (WVTR) — measured in g/m²/24h at specified conditions (commonly 38°C / 90% RH)

A third metric—CO₂ Transmission Rate—is relevant for modified atmosphere packaging (MAP) where controlled CO₂ levels suppress microbial growth. For fresh meat and produce applications, OTR is typically the defining design criterion.

Zhongcheng's technical innovation team has developed proprietary multi-layer co-extrusion processes that achieve commercial OTR values of under 5 cc/m²/24h/atm across their barrier shrink film product lines—suitable for chilled and modified-atmosphere fresh meat packaging without the need for additional coating steps.

The relationship between layer thickness ratio, EVOH mole % (ethylene content ranging from 27% to 48%), and resulting OTR follows well-established permeation models. Lower ethylene content in EVOH correlates with superior barrier but also increased brittleness and moisture sensitivity, requiring careful structural design to protect the EVOH core layer.

4. Shrink Film Technology

Shrink film is engineered to contract tightly around a product when exposed to heat, creating a conforming, tamper-evident seal. In food packaging, this has two primary applications: retail bundle wrapping and primary protein packaging.

The shrink behavior of a film is governed by its molecular orientation, introduced during manufacture through a process called tentering or blown bubble biaxial orientation. When heated above the film's orientation release temperature, these locked-in stresses relax—causing the film to shrink in the machine direction (MD), cross direction (CD), or both. Total free shrink values for high-performance barrier shrink films typically range from 40% to 75% at 90°C.

Key technical parameters for shrink film specification include:

Free shrink percentage at defined temperature (ASTM D2732)

Shrink force (N/25mm) — relevant for delicate or crushable products

Seal strength (N/15mm) — peel or shear mode

Optical haze (%) and gloss (GU at 60°) — determines retail appearance

Thickness uniformity (±% across web width)

Explore Zhongcheng's full shrink film product range, which includes standard POF shrink films as well as high-barrier variants designed for vacuum skin packaging (VSP) and modified atmosphere applications.

5. Lidding Film for Fresh Food Applications

Lidding film sits at the interface between the packaged product and the consumer—it must seal reliably, display the product attractively, resist fogging, and in many cases, be peeled or torn open cleanly at the point of use. These demands place lidding film among the most technically complex constructions in flexible packaging.

A high-performance lidding film typically consists of 5 to 9 co-extruded layers serving distinct functional roles:

Top layer (print/abuse layer): PET or OPP for stiffness, printability, and scuff resistance

Tie layers: Modified polyolefin adhesives bonding incompatible polymers

Barrier core: EVOH or PVDC for oxygen and gas barrier

Antifog layer: Polyolefin with surfactant additives to prevent condensation droplets

Seal layer: Peelable or non-peelable heat-seal resin compatible with tray substrate

Anti-fog performance is particularly critical for refrigerated display cases. Without an effective antifog coating, condensation droplets on the film interior scatter light, reducing product visibility and retail appeal. According to industry technical references, antifog agents function by reducing the surface tension of water—causing it to sheet out as a thin transparent film rather than forming discrete droplets.

Zhongcheng's lidding barrier shrink film products are specifically formulated to deliver outstanding antifog clarity alongside high oxygen barrier performance, making them well-suited for fresh meat, poultry, and seafood tray applications in chilled retail environments. Learn more about technical specifications on the technical innovation page.

6. Material Comparison Tables

The following tables provide a technical reference for the most common plastic film materials used in food packaging, comparing key barrier and mechanical properties.

Table 1 — Barrier Performance Comparison by Polymer

Table 2 — Typical Layer Structure of a 5-Layer Barrier Shrink Film

Table 3 — Shelf Life Extension by Packaging Type (Fresh Red Meat, 4°C)

7. Industry Applications

Plastic films in food packaging are used across virtually every fresh, chilled, and processed food category. The selection of film type is dictated by the product's biochemistry, retailer logistics, and regulatory requirements. Key application segments include:

Fresh Meat and Poultry

This is the most technically demanding application for barrier shrink and lidding films. Myoglobin chemistry in red meat requires precise control over oxygen exposure to maintain the bright cherry-red bloom consumers associate with freshness. High-oxygen MAP (70–80% O₂) is the dominant retail format in Europe and increasingly in North America, requiring lidding films with OTR below 10 cc/m²/day to maintain the internal atmosphere throughout shelf life. View Zhongcheng's meat packaging applications.

Seafood

Fish and shellfish packaging faces the dual challenge of oxygen barrier (to limit oxidative rancidity of lipids) and moisture barrier (to prevent dehydration and drip loss). Anti-drip films—those incorporating absorbent pad layers or functional coatings—are common in premium retail seafood. Shrink films for whole fish provide conforming coverage that minimizes headspace and improves cold chain efficiency.

Fresh Produce

Unlike meat, most fresh produce is still metabolically active post-harvest. Produce packaging therefore requires equilibrium modified atmosphere (EMA) films that are microporous or engineered with specific O₂:CO₂ permeability ratios to match the respiration rate of the specific commodity. A film that is too tight causes CO₂ build-up and anaerobic damage; too permeable allows rapid senescence.

Ready Meals and Convenience Foods

Dual-ovenable lidding films—capable of withstanding both microwave and conventional oven temperatures—represent one of the most challenging multi-property specifications in the industry. These films must maintain seal integrity up to 200°C while remaining peelable at room temperature, meeting food contact regulations across multiple jurisdictions. For further reading on this topic, see Zhongcheng's technical article: Recyclable Lidding Film for Ready Meal Trays.

8. Sustainability and Recyclability

The sustainability profile of plastic food films is complex. On one hand, a thin flexible film uses dramatically less material than the rigid alternatives it replaces; the carbon footprint per unit of food protected is often lower. On the other hand, multi-layer structures containing EVOH, PVDC, or adhesive tie layers are difficult to recycle in standard polyolefin streams.

The industry is actively pursuing several pathways to improve recyclability without sacrificing barrier performance:

All-polyolefin barrier films: Replacing EVOH with next-generation polyolefin barrier technologies that remain compatible with PE/PP recycling streams

Thin-layer EVOH structures: Reducing EVOH content below the 5% threshold considered acceptable by major recycling bodies such as RecyClass and CEFLEX in Europe

Design-for-recycle lidding films: Mono-material PE or PP lidding films engineered to achieve competitive OTR values through oriented structure and coating rather than co-extrusion

Chemical recycling compatibility: Ensuring multi-layer structures remain processable in pyrolysis or solvolysis pathways, even where mechanical recycling is not feasible

Zhongcheng actively invests in sustainable packaging R&D through its dedicated technical innovation program, which includes an 80+ member R&D team with senior and graduate-level engineers focused on next-generation film architectures. More can be found on their corporate social responsibility page.