In recent years, PET (polyethylene terephthalate) has been the packaging material of choice for water and soft drinks. Plastic bottles are increasingly being used for beer, juices, sports drinks, and aromatized alcoholic drinks. But each product requires specific qualities in its bottles.
PET continues to grow in popularity as an effective packaging material for beverage applications. It is robust, lighter in weight compared to other materials such as glass
and metal, and easily recyclable. The material also offers a high degree of design flexibility that enables packaging designers and brand managers to differentiate their products. Add low-cost production capability to the equation, and it’s clear why there is a steady rise in worldwide production of PET containers for beverages.
Figure: PET Jar/Bottle Usage In Years
However, like glass, transparent PET offers limited protection against ultraviolet (UV) wavelengths present in natural light and certain types of man-made lighting. PET can block wavelengths shorter than 315nm, but transmits light in the
UVA spectral region, between wavelengths of 315nm and 400nm. Many of today’s beverages are sensitive to UV light, or contain ingredients that are not stable in the presence of UV. This is typical with beverages that are rich in vitamins, coloured or contain flavouring.
WHY IS EXPOSURE TO UV LIGHT A CONCERN?
The impact of all these in uences is di erent for each product. For example, the taste of milk is particularly susceptible to UV and visible light. Carbonated soft drinks
and beer su er from CO2 loss. Beer and juices tend to oxidize with the O2 in the air. These di erent sensitivities lead to a variety of bottle designs adapted to the product at hand, including opaque bottles for milk and transparent brown bottles for beer.
UV light causes photo-oxidative degradation, a reaction that can adversely affect the taste, odor or color of a beverage. Degradation will affect shelf life, but it could also damage the image and integrity of a brand if consumers have a negative experience with the product.
Full bottle sleeves, opaque PET packaging or a combination of both, are used today to protect UV-sensitive products, but these methods can be limiting for packaging designers. In certain high-volume markets, such as juice and energy drinks, clear or transparent packaging allows brands to showcase the content.
Some energy drink brands, for example, use vibrant colors as marketing tools to provide differentiation and enhance consumer appeal. In the juice market, glass-like container clarity in a polymeric container can be used to help position a brand as ‘premium’ on the store shelves.
During processing, opaque bottles and sleeves can also increase production complexity with higher addition rates for opaque colors and additional process steps required for shrink wrapping sleeves. Both also add complexity to the PET recycling process and are generally not recommended by association bodies such as the European PET Bottle Platform.
Figure: Light Sensitivity
A lack of UV protection in clear and transparent packaging also affects beverage formulators, who are limited to creating products that
are ‘UV-safe’ or contain preservatives to counter the risk associated with UV exposure. However, there is growing consumer demand for healthier, preservative-free foods and beverages, and this often involves using an increasing number of UV-sensitive ingredients.
All these factors are forcing the industry to take a closer look at how PET packaging and beverage content function together in order to develop products that have aesthetic appeal, are easy to recycle and most importantly, reduce the risk of inferior product quality.
UV Blocker Transmission Chart
For brand owners and converters, adding a UV barrier additive during preform molding is an effective way to prevent UV-initiated product degradation in clear and transparent PET containers.
Standard PET blocks UV wavelengths up to around 315nm, but at 330nm it allows over 50% transmission, which is already enough exposure to initiate degradation for certain ingredients. With a light barrier additive added at 0.15%, UV transmission can be kept below an acceptable level for many applications.
We are happy to offer you UV-filter solution on our PET products including Jars and preforms.
FIVE WAYS UV BARRIER ADDITIVES CAN OFFER VALUE FOR PET APPLICATIONS:
1. RISK REDUCTION
Reducing the risk of quality degradation helps maintain brand integrity and consumer loyalty while minimizing the possibility of product recalls. A great deal of money and resource is invested in product development and tailoring packaging to maintain product quality is a way of providing insurance for that product
2. SHELF LIFE EXTENSION AND GLOBAL CONSISTENCY
Extending shelf life can reduce the chance of product degradation, but it also enables production flexibility. For example, a brand
or manufacturer could use a single site for production that serves various locations or geographies that may have varying supply chain demands and point of sale environments. An additive that provides broadband UV blocking can be used to meet content protection requirements around the world.
3. FORMULATION FLEXIBILITY
With UV protection, formulators have more flexibility to use UV sensitive ingredients and not rely on the formulation alone to be UV-stable. This can help brands meet the increasing global demand for healthier drinks with fewer preservatives and stabilizing compounds.
4. CONTAINER DESIGN FLEXIBILITY AND PRODUCTION EFFICIENCY
Packaging designers are not limited to opaque and sleeve constructions when designing containers for UV-sensitive beverages. Clear and transparent designs enable designers to react to market demands. Where UV barrier addition rates are low, they can also offer cost and process efficiencies over opaque coloration or sleeve shrink wrapping.
UV barrier additives that don’t affect PET clarity or quality during recycling help brand owners improve their sustainability credentials and in general enable more recycled PET to be used when producing new containers.
KEY CONSIDERATIONS WHEN USING UV BARRIER ADDITIVES IN PET
1. CONTAINER DESIGN AND THICKNESS
Some container designs and shapes have different thicknesses at different points in the container. There is a potential for ‘weak spots’ where the barrier additive is less concentrated and this could affect protection levels. It is always recommended to test the container at multiple points in the wall section (at least at the thickest and thinnest locations) to fully assess the UV barrier capability. It is always recommended to base your additive addition rate on the thinnest point in the wall section to ensure adequate protection across the entire container.
We are analyzing products for UV additives in our laboratories. We make sure wall thickness is valid.
2. PET COMPATIBILITY
Introducing additives always has the potential to pose challenges for production and technical teams. ‘Plate-out’ or mold deposit is a common problem when using additives in the injection molding process to make preforms. When additives are not specifically designed for use in PET or the processing parameters, they may migrate from the polymer matrix and form tiny deposits on the mold. This can lead to inferior preform quality and increased downtime. Careful selection of barrier formulations
can reduce the risk of plate-out and related processing issues.
3. CONTAINER CLARITY
Some UV additives can affect the clarity of clear and transparent PET containers. Where clarity is critical, it is important to specify high- performance additives that can be added at low addition rates and do not discolour the polymer or cause haze.
We work with only with best suppliers so container (jar or bottle) clarity is same with the products that has no UV-filtering option.