Time to read: 7 minutes

Transparent packaging: design considerations and sustainability trends

By: Marta Clavero

Valued at $120.60 billion in 2020, the transparent plastics market is projected to reach $193.67 billion by 2028, growing at a CAGR of 6.1% over the next few years. The growth comes as no surprise as transparent plastic plays a critical role in the consumer world, providing the opportunity to visually experience and evaluate a product before even purchasing it.

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Defining transparent packaging

Transparent packaging leaves nothing to the imagination; when the transparency is high, you should be able to see right through it.

 

Transparent plastics undergo moulding and extrusion processes, with the goal of achieving a high transparency value. This value is measured by two key factors:

1.   Light transmission (transmittance); the amount of light that can pass through

 2.   Haze: the amount of light that reflects back


Both light transmission and haze are factored in the design phase material selection. With light transmission, the higher the number, the better the transparency. With haze, it’s the opposite; the lower the number the more transparent the packaging is.

Designing transparent packaging

Across all transparent packaging, material selection is a balancing act. Compromise takes place at every step of the way to ensure neither performance nor transparency are sacrificed, and that it meets the regulations by the EU and FDA when required. The key design challenges that come with transparent packaging involve colour, formation, pressure streaks, resistance and weight.

Colour

Often, incorporating colour into transparent packaging is a unique way to visually differentiate products on the market. That said, when adding masterbatches of colour the transparency and recyclability will be affected.

Formation

Determining the thickness of the transparent packaging plays a role in the material selection. The thicker the formation, the more difficult it is to reach higher light transmission numbers.

Pressure streaks

When creating transparent packaging with an extrusion machine, there can be visual defects, such as streaking or black spots that are easily seen on the final sheet.

Additives can support this. In the extrusion phase, adding masterbatches or a surface treatment can help protect the transparency and keep the resistance at the level needed.

Weight

In some cases, light weight transparent packaging is the goal which is relatively easy to accomplish. In other situations, where glass is being replicated to create an expensive look, the weight can make a product appear more expensive and make achieving higher transparency more difficult as well.

Colour

Often, incorporating colour into transparent packaging is a unique way to visually differentiate products on the market. That said, when adding masterbatches of colour the transparency and recyclability will be affected.

Sustainability trends in transparent packaging

With consumer demand rising for sustainable packaging solutions, key challenges come into play when designing and planning end-of-life for transparent packaging.

Designing with bio-based content

When it comes to transparent packaging, using bio-based materials often lowers the light transmission, darkening the transparency. As a result, the haze number goes up, resulting in a cloudy or darker effect in the final product.

In some cases, this is not problematic, but when you are trying to display something behind transparent packaging, a cloudy or darker appearance could deter the end-user.

Translucent and opaque options are more common with bio-based polymers, but PLA is a bio-based polymer with higher transparency.

Recycling reusable, transparent packaging

Transparent packaging is often designed to be reused time and time again. This reduces waste and allows the packaging to reenter the waste hierarchy when it’s ready to be disposed of.

The challenge here comes in ensuring that when designing the product, it doesn’t lose its performance and durability for reuse, while maintaining transparency. Additionally, reusable products face challenges of reentering the waste hierarchy, with systems and recycling organizations having not adapted to the needs to reusability.

Sourcing and recycling transparent packaging

Today, manufacturers are prioritizing recycled materials in packaging to meet local regulations. But when layering recycled materials into transparent packaging, two challenges arise: material sourcing and end-of-life recycling.

Material sourcing

When using recycled materials in transparent packaging, all materials need to be traced back to the proper source to ensure the validity of the final properties. The challenge comes in sourcing these materials when they are coming from different life steams: post-industrial or post-consumer. This often results in impurities in the end-product, like dark spots and inconsistent densities.

Innovation in this regard is already happening. Some companies, like Eastman, have already started to work on molecular recycling products, allowing them to reintroduce certified post-consumer material in a range from 30% to 50% while maintaining the identical transparency properties of a virgin grade. For this to be successful, all the players on the value chain in this must be ISCC certified.
IMCD Expert Solution 
Using viscosity enhancers, compatibilizers and optical additives will unify recycled materials and improve the final appearance and transparency. Another approach is to use the ISCC products that are already chemically recycled using mass balance allocation.

End-of-life recycling 

When it comes to end-of-life for coloured transparent packaging, recycling becomes a bit more complex. Colours are more difficult to recycle and leave machines dirty. That’s why companies, like CocaCola, are making the switch from colored to transparent in an effort to go green.
IMCD Expert Solution
If you want to recycle transparent packaging, make sure all sources are from transparent and high-quality materials. If that’s not possible, recycle the materials with black sheets to avoid visual defects and/or implement the use of purging compounds to clean the machines.

This should be done even more often when using post-consumer recycled materials, as the materials tend to increase the amount of dirt the machines take on as compared to when using virgin grades. Additionally, this will increase their efficiency between product runs using less energy in production.

Case study

Uncover how one company created sustainable multi-layer food packaging

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Marta Clavero

With more than 20 years working with advanced materials, Marta has a wide range of experience across all areas of thermoplastics, including the design, development, analysis, and application. Marta is a sales manager based in Spain and also leads the global Packaging Expert Team. Her experience  in wastewater treatment, papermaking, oil & gas, mining, agriculture, cosmetic polymer ingredients, textiles, and other derivative sectors has prepared her to support IMCD customers in developing innovative solutions that differentiate their products on the market.

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