Choosing the right EVOH barrier plays a vital role in extending shelf life for packaged products. EVOH excels at blocking oxygen, which helps maintain food freshness, color, and nutritional value.
- EVOH provides exceptional protection against gases, especially oxygen, making it essential for food packaging.
- It significantly outperforms other barrier materials in preserving product quality.
Different EVOH grades affect how well products last and how they look. Manufacturers use lami tube making machine to create multilayer packaging that utilizes EVOH’s unique properties. The following section, EVOH barrier, explores why EVOH remains a top choice for extending shelf life.
Key Takeaways
- EVOH barrier significantly extends the shelf life of packaged products by blocking oxygen, preserving freshness, color, and nutritional value.
- Choosing the right EVOH grade is crucial. Lower ethylene content grades offer ultra-low oxygen transmission, ideal for sensitive products.
- Multilayer films with EVOH provide superior barrier performance compared to monolayer alternatives, justifying their higher cost for high-protection applications.
- Moisture exposure can degrade EVOH’s barrier properties. Combining EVOH with other materials enhances overall protection against spoilage.
- Sustainability matters. Many EVOH packaging options are recyclable, supporting eco-friendly practices and compliance with environmental standards.
EVOH Barrier Explained
What Is EVOH?
EVOH, or ethylene-vinyl alcohol copolymer, stands out in packaging for its remarkable gas barrier properties. The chemical structure of EVOH features high intrinsic crystallinity and strong intermolecular bonds. These characteristics create a dense material that resists the passage of gases, especially oxygen. EVOH barrier explained often highlights its resistance to oils, solvents, and flavors, which helps maintain the integrity of packaged food and other products. The hydrophilic nature of EVOH, due to its hydroxyl content, allows water molecules to penetrate the polymer structure. This property can lead to swelling and plasticization, which may affect barrier performance in humid environments.
EVOH copolymers absorb moisture, and this can impact oxygen barrier properties, especially when humidity exceeds 10% by weight at equilibrium.
| Chemical Property | Contribution to Oxygen Barrier Effectiveness |
|---|---|
| High intrinsic crystallinity | Enhances the material’s density and reduces the permeability to gases like oxygen. |
| Strong intermolecular bonds | Polar hydroxyl groups create strong interactions that resist the passage of non-polar molecules such as oxygen. |
| Resistance to non-polar molecules | Prevents oxygen transmission, crucial for maintaining the quality and shelf life of packaged goods. |
| Imperviousness to Carbon dioxide and Nitrogen | Retains unreactive atmospheres, extending shelf life and quality of contents. |
| Resistance to oils, solvents, and flavors | Prevents contamination and loss of flavor, ensuring the integrity of the packaged product. |
| Hygroscopic nature | Provides excellent barrier properties, but exposure to moisture can reduce effectiveness. |
Oxygen Barrier Properties
EVOH barrier centers on its ability to block oxygen. EVOH film achieves an oxygen transmission rate as low as 0.01 cc/m²·day·atm, which is 50 times better than PVDC. This exceptional performance makes EVOH a preferred choice for food packaging, where extending shelf life is critical. EVOH is not effective as a standalone layer because it is brittle and sensitive to moisture. Manufacturers coextrude EVOH with other polymers to balance oxygen barrier properties and moisture resistance. EVOH barrier also notes that EVOH films can reduce oxygen permeability by up to 10,000 times compared to standard PE films.
Multilayer Films and Manufacturing
Laminated tube and multilayer film structures use EVOH to maximize barrier properties for PBL tube. The laminated tube making machine enables precise layering of EVOH between protective polymers, reducing moisture sensitivity by up to 80%. Multilayer films with EVOH offer superior barrier performance compared to monolayer alternatives, justifying their higher cost for applications needing high protection. Modern advancements allow for mono-material EVOH films, which improve recyclability and align with sustainability goals. Manufacturers rely on lami tube making machine to produce packaging that meets regulatory standards and consumer expectations for quality and shelf life.
| Feature | Multilayer Films with EVOH | Monolayer Alternatives |
|---|---|---|
| Barrier Properties | Superior | Standard |
| Cost | Higher | Lower |
| Ideal Applications | High protection needed | General use |
| Long-term Benefits | Justified investment | Limited |
Selecting EVOH Grades
Ethylene Content and Performance
Selecting the right grade of ethylene vinyl alcohol copolymer is essential for achieving optimal barrier properties in packaging. EVOH grades differ mainly in their ethylene content, which influences the oxygen barrier, clarity, and flavor retention of packaged food products. Lower ethylene content grades, such as L101A with 25 mol%, provide ultra-low oxygen transmission rates, making them ideal for shelf-stable food applications and pharmaceutical packaging material. Higher ethylene content grades, like EV 4405F with 32 mol%, offer greater flexibility and are suitable for multilayer packaging and deep-draw applications.
The ethylene content also affects the crystallinity of the EVOH film. Grades with higher ethylene levels tend to have increased transparency and gloss, which enhances the visual appeal of food packaging. These grades help maintain flavor and freshness by reducing oxygen permeability, which is crucial for food preservation and food safety. The table below compares common EVOH grades used in packaging:
| Product Model | Ethylene Content | Typical Applications | Key Advantages |
|---|---|---|---|
| EV 3201F | 27 mol% | Food packaging, bottles, sheets | Excellent oxygen barrier with good flexibility |
| EV 3251F | 28 mol% | Food packaging, bottles, sheets | High processing stability for fast-speed equipment |
| EV 3851F | 29 mol% | Food packaging, thermoforming | Soft and suitable for forming and deep-draw packaging |
| EV 4405F | 32 mol% | Food packaging, thermoforming | High ethylene content, great flexibility for multilayers |
| L101A | 25 mol% | High barrier and pharmaceutical | Ultra-low OTR, ideal for sensitive products |
| K102 | 30 mol% | Food packaging, bottles, sheets | High transparency and stable barrier performance |
| F171B | 31 mol% | Food packaging, automotive parts | Versatile, suitable for thermoforming and co-structures |
| E105B | 26 mol% | Food packaging, thermoforming | Easy to process, cost-effective |
Tip: Higher ethylene content in EVOH grades increases clarity and gloss, making packaging more attractive for consumers.
Melt Viscosity and Process Compatibility
Manufacturers must consider melt viscosity when selecting EVOH grades for high-speed production. Melt viscosity determines how easily the polymer flows during processing, which affects compatibility with equipment such as laminated tube making machine. Grades with stable viscosity, like EV 3251F, perform well in fast-speed coextrusion and laminated tube production. The design of the screw and temperature control systems in the laminated tube making machine ensures uniform plasticization and prevents degradation of the polymer.
Key process parameters include:
- Length-to-diameter ratio of 25:1–35:1
- Compression ratio of 2.5:1–4:1
- Segmented temperature control within ±1°C
- Servo motor-driven screws with rotational speed fluctuation ≤±1 rpm
The table below highlights how viscosity matching and temperature control can improve barrier performance and reduce energy consumption:
| EVOH Grade | Viscosity Matching | Coextrusion Tolerance | Energy Consumption Reduction |
|---|---|---|---|
| EW-3201 | Better | ±5°C | Over 15% |
Efficient processing not only lowers manufacturing costs but also supports food security by enabling consistent production of packaging material for perishable products.
Shelf Life Impact
The choice of EVOH grade directly influences the shelf-life performance of packaged food products. Grades with superior barrier properties, such as L101A and EV 3201F, significantly reduce oxygen permeability, which is vital for extending shelf life and maintaining food quality. Multilayer structures that incorporate EVOH enhance the effectiveness of packaging by preserving the gas composition inside, slowing transpiration, and reducing weight loss in perishable foods.
| Key Point | Description |
|---|---|
| Barrier Properties | EVOH provides excellent barrier properties against gases like oxygen and carbon dioxide, crucial for food quality. |
| Oxygen Permeability | Using EVOH significantly reduces oxygen permeability, extending food shelf life. |
| Multilayer Structures | Combining EVOH with other materials enhances its effectiveness in preserving food quality. |
| Impact on Gas Composition | High barrier films affect gas composition, leading to lower O2 and higher CO2 concentrations, which slow transpiration and weight loss. |
| Application Examples | EVOH packaging has been used for mushrooms, milk, high transpiring fruits, and white cheese to extend shelf life. |
Case studies show that high barrier pouches made with advanced EVOH grades can achieve shelf lives of 3–5 years at room temperature. Double-layered PET pouches and foil packaging also serve as excellent alternatives for extended shelf-life performance.
| Packaging Type | Shelf Life (Years) | Temperature (°C) |
|---|---|---|
| High barrier pouches | 3–5 | 23 |
| Double-layered PET pouches | Excellent alternative | N/A |
| Foil packaging | N/A | N/A |
Cost considerations play a role in grade selection. While high-performance barrier films may cost more, they offer longer shelf lives and reduce spoilage, making them cost-effective for high-value food and shelf-stable food applications. Processing efficiency, such as faster sealing times with laminated tube making machine, further lowers manufacturing costs. Sustainability fees for non-recyclable materials encourage the use of recyclable EVOH grades, supporting food safety and environmental goals.
Note: Choosing the right EVOH grade ensures extended shelf-life, improved food preservation, and reliable barrier performance for packaged food products.
Barrier Packaging Applications
Food Packaging Needs
Manufacturers rely on EVOH for barrier packaging because it provides a powerful shield against oxygen. This feature helps maintain freshness and quality in food products. EVOH limits oxygen exposure, which prevents spoilage and supports longer shelf lives. Common food packaging applications include dairy products like cheese and yogurt, fresh and processed meats, bakery items, snacks, drinks, and frozen foods. These perishable products benefit from the superior barrier properties of EVOH, reducing the need for preservatives and supporting food security.
- Dairy products (cheese, yogurt, milk)
- Fresh and processed meats, seafood, shellfish
- Bakery items (bread, cakes, pastries)
- Snacks and sweets (potato chips, chocolate, candies)
- Drinks (juices, sodas, alcoholic beverages)
- Frozen foods (pre-made meals, vegetables, ice cream)
EVOH also finds use in cosmetic tubes and pharmaceutical blister packs, where it prevents fragrance loss and protects against moisture.
Product Sensitivity Factors
The selection of EVOH grade and barrier thickness depends on the oxygen sensitivity of the product. Products that spoil quickly require packaging material with lower oxygen transmission rates and thicker barrier layers. The formulation and processing methods of EVOH influence barrier performance. Moisture exposure can degrade the barrier properties of EVOH, especially in humid environments. To address this, manufacturers often combine EVOH with PET or polyamide to enhance overall barrier protection. These strategies help maintain the integrity of sensitive products and ensure reliable shelf-life extension.
Tip: For highly sensitive products, choosing the right EVOH grade and combining it with other materials improves barrier performance and protects against moisture.
Sustainability and Compliance
Sustainability plays a growing role in barrier packaging decisions. EVOH in multilayer packaging has received recyclability certification from organizations such as APR and RecyClass. For rigid containers, EVOH can make up to 6% of the weight for HDPE and PP, while flexible packaging allows up to 5% for PE. The industry continues to develop recyclable materials and advanced recycling technologies to improve recovery rates. The ISCC PLUS scheme certifies bio-based and chemically recycled EVOH-based packaging materials, supporting eco-friendly practices.
| Certification | Description |
|---|---|
| ISCC PLUS | Certifies bio-based or chemically recycled EVOH packaging materials |
EVOH barrier are designed for easier sorting and recycling, promoting a circular economy and reducing waste. Manufacturers must consider regulatory requirements and environmental impacts when selecting barrier packaging solutions.
Conclusion
Selecting the right EVOH barrier depends on several factors. Manufacturers evaluate physical, mechanical, thermal, and chemical properties. They also consider optical qualities, processing methods, barrier performance, recycling potential, regulatory compliance, and cost. The table below highlights these decision points:
| Factor | Description |
|---|---|
| Physical Properties | Lightweight materials for cost and sustainability |
| Mechanical Properties | Performance at different temperatures |
| Barrier Properties | Oxygen and moisture protection |
| Recycling | Sustainability and waste reduction |
Manufacturers should consult suppliers and confirm compatibility with laminated tube making machine before finalizing packaging choices.
FAQ
What Is the Main Benefit of Using EVOH in Packaging?
EVOH provides a strong barrier against oxygen. This feature helps keep food fresh and safe for longer periods. Manufacturers choose EVOH to extend shelf life and maintain product quality.
How Do Manufacturers Select the Right EVOH Grade?
Manufacturers look at ethylene content, melt viscosity, and barrier performance. They match the EVOH grade to the product’s sensitivity and packaging needs. Compatibility with production equipment also matters.
Can EVOH Packaging Be Recycled?
Many EVOH multilayer packages meet recyclability standards. Organizations like APR and RecyClass certify these materials. Manufacturers use recyclable EVOH barrier grades to support sustainability goals.
Why Is Melt Viscosity Important for EVOH Processing?
Melt viscosity affects how EVOH flows during production. Stable viscosity ensures smooth operation on machines like laminated tube making machine. This helps maintain barrier quality and reduces waste.
Which Products Benefit Most from EVOH Barrier?
Food items such as dairy, meat, and snacks gain the most from EVOH barrier. Cosmetics and pharmaceuticals also use EVOH to protect against oxygen and moisture.