Protecting liquid products from oxygen and moisture is not just about keeping them safe inside a package—it’s about controlling how much external elements come in contact with the product.
Ambient air exposure can cause many products to lose colour, flavour, potency, and shelf life at alarming rates.
Packages provide protection against oxygen and moisture, which are extremely important to the food, drug, and chemical packaging industries. Liquid products can’t come into contact with even trace amounts of oxygen or water vapor without risk of spoilage or contamination.
One way packages can help restrict oxygen and moisture is through high-barrier packaging. It helps limit how much outside material can permeate the packaging and come into contact with the product. Applications for high barrier packaging help improve product quality and longevity while allowing for safe storage and transport from anywhere to everywhere.
At Srlon, we take great pride in our high-barrier plastic bottles. Designed with EVOH-based multi-layers, our bottles provide dependable oxygen protection.
In this article, we will discuss what barrier packaging is, what materials it uses to achieve high performance and other important information you should know.
What is Barrier Packaging?
Barrier properties in packaging play a key role in extending shelf life by preventing the ingress of oxygen and moisture into the package. Small amounts of oxygen and moisture can drastically affect quality and shelf life. Oxygen can cause spoilage in foods and beverages, loss of potency with pharmaceuticals, and changes in the chemical makeup of many products. Many chemical solutions will degrade with minimal exposure to moisture.
In order of priority, packaging systems are designed to control moisture and oxygen. Oxygen will cause oxidative reactions, resulting in color changes, flavor loss, and other unwanted chemical changes. Moisture can impact product texture/stability and promote microbial growth. Eliminating outside oxygen and moisture from the package is critical to extending shelf life.
Eliminating oxygen ingress starts with a multi-layered laminate that strategically places barrier materials where they are most effective. Outer layers typically serve as structural strength providers and can be made of multiple materials (PP or PET) that offer moisture barrier properties. While these materials serve a distinct purpose, they are poor at providing oxygen barrier properties. EVOH serves as an oxygen barrier and is perfect for use as the middle barrier layer of a 5-layer structure.
How Do We Measure How Good a Barrier Is?
The effectiveness of a barrier is assessed by measuring its WVTR (Water Vapor Transmission Rate) and OTR (Oxygen Transmission Rate). In both WVTR and OTR, the lower the number, the better that material is at preventing outside moisture/oxygen from entering the package.
1- Water Vapor Transmission Rate (WVTR)
This measurement determines how much moisture will pass through a specific material over a period of time.
Humidity can cause many adverse effects to products. Stability, texture, and overall quality can change when exposed to excess moisture. PP and PE provide excellent barriers against moisture and are often used within barrier structures.
2- Oxygen Transmission Rate (OTR)
This measurement determines how much oxygen will pass through a specific material over a period of time. Oxygen can drastically change the life of a product. Foods, such as sauces and liquid-based foods, will turn an undesired color when exposed to oxygen.
EVOH provides one of the lowest rates of OTR. For application purposes, we laminated the EVOH into a 5-layer structure (PP / Tie / EVOH / Tie / PP) to provide exceptional and consistent performance.
Materials Used For Barrier Packaging
Barrier technology mainly applies materials of various properties together. Different materials have different functions.
Metal (Aluminum)
It has the best barrier effect on oxygen and moisture. The disadvantage is that aluminum has been used less in plastic bottle packaging. The reason is that it’s too heavy and lacks flexibility. In addition, the shapes available are limited.
Glass
Barrier performance of glass bottles is very good. The disadvantage is that it is fragile. Heavier than plastic bottles.
Plastic Materials with Barrier Layers
Advanced barrier packaging is most commonly made from plastics with functional barrier layers. Products such as PP and PE are great when it comes to moisture barrier and physical strength, however they lack oxygen barrier properties.
For oxygen sensitivity, material EVOH (Ethylene Vinyl Alcohol) provides a high level of oxygen barrier performance. EVOH works to protect products that are vulnerable to oxidation by significantly reducing oxygen transmission. EVOH works to preserve products that are susceptible to oxidation.
In end-use applications, EVOH is combined with structural plastics using a multi-layer co-extrusion. For example: 5-layer construction (PP / Tie / EVOH / Tie / PP). This results in optimum performance with balanced strength/flexibility/high barrier properties.
At Srlon Group, we use this combo of materials to produce high barrier plastic bottles with reliable protection and long term stability.
Barrier Technologies: Coatings vs Multi-Layer Structures
High barrier plastic bottles are made using multi-layer co-extrusion technology. With multi-layered bottles, the barrier layer is incorporated into the bottle’s body. This provides more uniform performance, increased durability, and barrier properties during storage and transportation.
Multi-Layer Plastic Bottles are Made with Co-extrusion.
High-barrier plastic bottles are produced through co-extrusion. Multiple layers of material are combined and extruded together to form one piece with several layers. Each layer of material is responsible for providing a different property to the bottle wall.
One of the most popular structures is a 5-layer build (PP / Tie / EVOH / Tie / PP). Here, the EVOH provides the majority of the oxygen barrier performance. By adding a layer of EVOH, you drastically reduce the amount of oxygen that will penetrate the bottle. However, EVOH lacks moisture-barrier properties and does not add strength to the bottle. That is why it is sandwiched between 2 layers of material that provide moisture barrier properties and strength to the bottle.
These layers work together to provide your bottle with the perfect balance of barrier properties, durability, and performance for packaging liquids.
Multi-Layer Barrier Technology: The Sandwich Approach
A single layer of barrier material cannot provide reliable protection. During manufacturing, minute defects can develop that allow oxygen and/or moisture transmission far greater than the material is rated for.
Instead, multiple layers of differing materials are put together to form packages with uniform and dependable barrier properties.
One of the most common forms of high-performance packaging is a 5-layer co-extruded structure consisting of PP / tie / EVOH / tie / PP. The outer polypropylene provides structural strength and resistance to moisture. EVOH forms the middle layer of the structure and acts as the oxygen barrier. The tie layers provide strong adhesion between the packaging layers.
The same concept is used for co-extruded high-barrier plastic bottles. During the bottle manufacturing process, the multiple layers are combined and extruded at the same time. The EVOH barrier layer is positioned in the center of the bottle wall.
This provides protection to the barrier layer from the environment while allowing it to perform as expected. The bottle has added strength while providing superior barrier properties when compared to a single-layer structure. Multiple layers work together so that any one layer’s weaknesses are compensated for by the strengths of another. Therefore, your product is provided with a barrier to oxygen and moisture for the life of the product.
At Srlon, our 5-layer co-extrusion process is tightly controlled so that each layer is evenly distributed and the EVOH layer is centered precisely.
Sealing and Barrier Integrity in Plastic Bottles
Optimum barrier performance is also influenced by the ability of the package to be effectively sealed. If there is inadequate sealing system integrity oxygen/moisture can still enter the package compromising its contents regardless of the barrier package design.
Plastic bottles rely heavily on the structure and closure method for sealing. Effective sealing keeps the interior contents of the package safe during storage handling and use.
Closure integrity is also important when designing a high barrier bottle. Making sure the barrier layer such as an EVOH layer is intact during storage and use is critical. The beauty of having a barrier layer co-extruded within the bottle wall is that the layer is hidden from view. During the bottle production process the barrier layer will not be cut or exposed to the surface like a laminate layer would.
This also eliminates the possibility of the barrier layer being compromised during storage or use. Product compatibility between the bottle and cap/closure is also very important. If the cap fits snugly and correctly there will be no leaks oxygen transmission or product contamination.
Our Bottle design and co extrusion process work seamlessly to provide you with a package that offers you a reliable seal ensuring barrier structure integrity along with structural stability and predictable performance for a variety of liquid packaging applications.
Where We Use Barrier Packaging in Everyday Life
Barrier packaging is used extensively for products of all kinds every day. Oxygen- and moisture-sensitive products, whether food-grade or pharmaceutical-grade, require a high barrier packaging for extended shelf life and better product safety.
Food and Beverage packaging
Barrier protection against oxygen is one of the most crucial packaging components that impact shelf life. Food/beverage products such as sauces, condiments, and jelly are very sensitive to oxygen and need complete protection from it.
The EVOH barrier layer in high-barrier plastic bottles provides excellent oxygen protection, thereby allowing the products to retain their color, flavor, and overall quality during storage and transportation.
Facilitating a longer shelf life along with lesser requirements for chemical preservatives is now possible with barrier packaging using a 5-layer bottle structure that sandwiches the EVOH layer between external abrasion-resistant layers for moisture protection as well.
Pharmaceutical Packaging
The stability of the contents within the package is of utmost importance in pharmaceutical packaging. Drugs and liquid formulations are highly sensitive to even slight changes in storage conditions.
By providing a stabilized barrier against oxygen and offering high moisture resistance, high barrier bottles keep these products protected from all external factors that may degrade the quality of the product within, ensuring user safety from manufacture till the time of use.
Barrier protection has been mastered by Srlon Group for high barrier plastic bottles, which are manufactured keeping pharmaceutical requirements in mind.
Conclusion:
High barrier packaging is truly one of those foundational technologies that people rarely stop to think about. Barrier packaging keeps oxygen, moisture, and humidity out while protecting your products. Another benefit to high-barrier packaging is that it enables brands to offer products without preservatives. Thanks to its excellent protection from outside elements, high barrier packaging can help products maintain a long shelf life, even without preservatives. It can be especially helpful for clean-label products.
The Srlon is innovating smarter multi-layer bottles every day—making products safer and last longer. We are one of China’s premier suppliers of high-barrier bottles and offer clients a one-stop solution for all of their custom barrier bottle needs. Srlon is capable of machine design and production, mold prototyping, and finished bottle production—all under one roof.
