PP/EVOH/PE trays are a type of multi-layer plastic packaging widely used, particularly in the food industry. They are designed to provide excellent barrier properties and extend the shelf life of fresh products like meat, fish, and other sensitive foods.

Here’s a breakdown of what each component contributes:

PP (Polypropylene): This is the structural base of the tray, providing mechanical strength, heat resistance, and chemical resistance. It’s a durable and versatile plastic.

EVOH (Ethylene Vinyl Alcohol): This is the key barrier layer. EVOH is highly impermeable to gases like oxygen and carbon dioxide, as well as to aromas and flavors. This prevents spoilage and maintains the freshness of the packaged food.

PE (Polyethylene): This layer is typically used to improve the heat-sealing capabilities of the tray, ensuring a strong and leak-proof seal with a lidding film.

How they are manufactured:

PP/EVOH/PE trays are typically produced using a co-extrusion process. This involves melting and extruding the different plastic polymers (PP, EVOH, and PE) simultaneously through a die to form a multi-layer sheet. This sheet is then thermoformed into the desired tray shapes. Tie-layers or adhesives are often used between the different polymer layers to ensure they bond effectively.

Advantages of PP/EVOH/PE trays:

Excellent Barrier Properties: The EVOH layer significantly extends the shelf life of food by preventing oxygen ingress and maintaining a protective atmosphere, especially for products packed in modified atmosphere packaging (MAP) or skin-packed.

Extended Shelf Life: This leads to reduced food waste, which is a significant environmental and economic benefit.

Good Mechanical and Thermal Resistance: PP provides durability, allowing the trays to withstand various handling and temperature conditions, including freezer-to-microwave convenience (typically -20°C to 100°C).

Food Safety: They comply with strict food safety regulations and provide effective protection against contamination.

Attractive Presentation: These trays often offer good clarity and can be designed in various shapes, sizes, and colors, enhancing product appeal at the point of sale.

Versatility: They are used for a wide range of sensitive food products, including fresh meat, poultry, seafood, and plant-based proteins.

Disadvantages and Recycling Challenges:

Higher Cost: Compared to single-material PP trays, multi-layer PP/EVOH/PE trays generally have a higher manufacturing cost due to the additional materials and complexity.

Recyclability Challenges: This is a significant concern. While the individual polymers (PP and PE) are recyclable, the multi-layer structure makes it difficult to separate them in standard recycling processes.

Most recycling facilities are not equipped to efficiently separate these layers, which can lead to the material being diverted to landfills or incineration.

If the EVOH content is kept very low (typically below 5-6%), it can sometimes be processed within the PP or PE recycling streams without significant disruption, but this is not always guaranteed or widely implemented.

New innovations and efforts in eco-design are focusing on creating “mono-material” solutions or improving the recyclability of these multi-layer plastics.

In summary: PP/EVOH/PE trays are highly effective for preserving sensitive foods and extending their shelf life, offering significant benefits in terms of food safety and waste reduction. However, their multi-layer composition presents challenges for traditional recycling, leading to ongoing efforts to improve their end-of-life management and develop more circular solutions.

PP Evoh PE Trays

PP/EVOH/PE trays are multi-layer plastic packaging solutions primarily used in the food industry for products that require extended shelf life and protection from oxygen and moisture. Let’s delve into their characteristics, manufacturing, and recycling challenges.

What they are:

These trays are composed of three distinct layers, each contributing specific properties:

PP (Polypropylene): This forms the bulk of the tray and provides structural rigidity, mechanical strength, and heat resistance. It’s an excellent base material due to its durability.

EVOH (Ethylene Vinyl Alcohol): This is the critical barrier layer. EVOH exhibits exceptional impermeability to gases like oxygen and carbon dioxide, as well as to aromas and flavors. This prevents spoilage, maintains product freshness, and is particularly important for Modified Atmosphere Packaging (MAP). EVOH’s barrier properties are, however, sensitive to humidity, so it’s usually sandwiched between moisture-resistant layers.

PE (Polyethylene): This layer typically serves as the heat-sealing layer, ensuring a strong and secure seal with lidding films, preventing leaks and maintaining the integrity of the package. PE also offers a good moisture barrier.

How they are made (Manufacturing Process):

PP/EVOH/PE trays are generally manufactured using a co-extrusion and thermoforming process:

Co-extrusion: Different plastic resins (PP, EVOH, PE) are melted in separate extruders and then fed simultaneously through a single die. This process creates a multi-layer sheet where the layers are bonded together. Tie-layers (adhesives) are often used between incompatible layers (like PP/EVOH or EVOH/PE) to ensure proper adhesion.

Cooling and Shaping: The hot, co-extruded sheet is then cooled by passing it over chill rolls. These rolls also help to control the sheet thickness and surface texture.

Thermoforming: The cooled multi-layer sheet is then heated again and placed over a mold. Vacuum and/or pressure are applied to form the sheet into the desired tray shape.

Trimming: Excess material is trimmed away, leaving the finished trays.

Properties and Advantages:

Excellent Barrier Properties: The EVOH layer significantly extends the shelf life of perishable foods by preventing oxygen ingress, maintaining the product’s quality, color, and nutritional value. This is crucial for products like fresh meat, poultry, seafood, and ready meals.

Extended Shelf Life: This directly translates to reduced food waste, a major benefit both economically and environmentally.

Mechanical Strength and Rigidity: The PP layer provides good stiffness and impact resistance, protecting the contents during transport and handling.

Heat Resistance: PP allows the trays to withstand various temperature conditions, including refrigeration, freezing, and often microwaving (typically up to 120°C). Some PP/EVOH/PP structures are even suitable for retort (sterilization) processes.

Chemical Resistance: PP and EVOH offer good resistance to various chemicals, acids, alkalis, and oils, making them safe for a wide range of food products.

Transparency: Many formulations can offer good transparency, allowing consumers to visually inspect the product, which is important for fresh produce and meats.

Versatility: They are adaptable to various packaging formats and can be used with Modified Atmosphere Packaging (MAP) or vacuum sealing.

Recycling Challenges:

Despite their advantages, PP/EVOH/PE trays face significant challenges in recycling:

Multi-layer Structure: The primary hurdle is that they are made of different types of plastic (PP, EVOH, PE) fused together. Traditional mechanical recycling processes are designed to sort and process single-polymer streams. Separating these layers is technically difficult and economically unfeasible for most recycling facilities.

Incompatibility: When multi-layer plastics are processed together, the different melting points and chemical properties of the polymers can lead to a degraded, lower-quality recycled material with compromised mechanical properties. The EVOH, even in small percentages, can negatively affect the properties of recycled PP or PE if not properly separated.

Limited Infrastructure: Most existing recycling infrastructure is not equipped to efficiently sort and process multi-layer flexible or rigid plastic packaging. This often results in these trays being diverted to landfills or incineration.

EVOH Content: While some studies suggest that EVOH content below a certain threshold (e.g., 5-6%) might be tolerated in polyolefin recycling streams without significant disruption, this is not universally accepted or consistently implemented across all recycling facilities.

Current Outlook:

The industry is actively working on solutions to improve the recyclability of high-barrier packaging. This includes

Eco-design: Developing mono-material solutions (e.g., all PP with a thin, compatible barrier layer) or designing layers that are more easily separable.

Advanced Recycling Technologies: Exploring chemical recycling or dissolution technologies that can break down mixed plastics into their original monomers or valuable feedstocks.

Improved Sorting: Investing in advanced sorting technologies (e.g., AI-powered optical sorters) that can better identify and separate complex plastic packaging.

In essence, PP/EVOH/PE trays are highly effective for food preservation and extending shelf life, but their multi-material nature poses a significant challenge for achieving a truly circular economy for plastics