“Working together is success”

A lightbulb moment led to the development of a new material. Here’s how three companies came together to make that happen while incidentally demonstrating the importance of collaboration in the value chain.  

“It’s truly a team accomplishment,” emphasised Owen Lightbody, who  leads the performance films technical service team in Nova Chemicals’ Innovation department. So what is so special about HD-BOPE?

Quite a lot, apparently.  As Nova Chemicals describes it, though, it is primarily an important building block to help brand owners reach their packaging sustainability goals.

A lot of application development done at Nova focusses on the development of new packaging solutions, explained Owen Lightbody. It is why, several years ago, the company became interested in oriented films and specifically, in biaxially oriented polyethylene – BOPE - in the first place.

“There is a huge emphasis on recycling and with BOPE, we saw we could help the industry transition to a circular economy,” said Lightbody. First, however, the company head to learn more about the oriented films and the processes used to produce these.

“It began with machine directional orientation and then we started learning about the tenter frame process and biaxial films - how the process dramatically improves the performance of polyethylene. Extremely impressive,” noted Lightbody.

“Then, during one of our first trials, we found that with LLDPE, we could make film the first day. But with HDPE – well, everything was failing, it wasn’t running through the machine and that’s when the lightbulb went on in our heads: this is what the market needs, this is where innovation needs to happen.”

However, it was clear that this was a project requiring more knowhow than the company had. It needed to find a partner able to provide the technical expertise that Nova was lacking.

“And when you look at the biax film market, there’s really one dominant player, and that’s Brückner,” Lightbody concluded. Nova reached out to Brückner and explained what it was trying to do. Their contact at Brückner, senior sales manager Sebastian Ruhland, immediately realised the potential for collaboration.

“We also saw HD-BOPE as the key to monomaterial packaging and therefore to recyclable packaging design,” he said. The companies have worked closely together ever since.

A new resin

Using its deep understanding of what was necessary from a resin perspective Nova Chemicals went to work on the development of a new HDPE grade specifically for the biax film process. The film needed to provide stiffness, heat resistance, low tear and good optics.

Also, for converters processing the film, it needed to be similar to be similar to BOPP. “People are always resistant to change,” said Lightbody.

“LLDPE doesn’t have the heat resistance, which gives you usability and a wider process window on packaging lines. And BOPP has great stiffness, which LLDPE can’t match – but HDPE can. It’s these two aspects of heat resistance and the stiffness that really make HD BOPE more suitable for packaging – so for example for vertical form-fill-seal or long preform-fill-seal, such as stand-up pouches.”

Together,  Brückner and Nova started learning about the equipment needed to produce HD BOPE. They found that while it was possible to use an existing tenter frame line – “it’s exactly the same MDO and TDM; typically for a BOPP line you’re stretching five times in the machine direction and nine times in the transverse direction,” said Lightbody -  although modifications were needed, as the machine was not optimised for polyethylene.

The team complete

Realising that another partner was needed – a converter who was open to innovation and new ideas – Brückner introduced Nova Chemicals to one of their customers, Polivouga, at K 2019, in Düsseldorf.  

As Owen Lightbody described it: “That meeting went very quickly from ‘are we going to work together?’ to ‘how are we going to work together’.” One of the most important factors in getting an innovation to market successfully is the choice of partners. Collaboration demands openness and transparency – “Otherwise your project really just gets stuck, you get bogged down and lots of times you don’t get anywhere or don’t achieve results as quickly as you could,” he said.

Polivouga, a Portuguese  family-run company that invested in its first biaxial film lines in 2015 and 2016, are very focused, ambitious and serious about new equipment. The company has two lines, that run at 3-5 thousand kgs per hour.

“Massive pieces of equipment,” said Lightbody.  

“Polivouga is innovation oriented,” added  Diogo Barros, the production engineer at Polivouga with whom the two other partners mainly interacted. “Three years ago, we started working with several sustainable projects and one of them was monomaterial packaging.”

Polivouga was eager to collaborate, added Barros. “In addition to being a BOPP producer, we also produce blown and cast film and offer a wide range of solutions in flexible packaging for industrial, food packaging, retail applications and agriculture in a global perimeter. Nova Chemicals has as well a wide resin portfolio for special applications, which can match perfectly in some that we are present.”

The company was extremely interested bringing a new material to the flexible packaging market, and, said Barros, ‘the first time that we had contact with Nova Chemicals they presented to us a promising resin for BOPE, with the mechanical properties that we were looking for.’

Sebastian Ruhland: “The results from the trials were very promising, so we directly brought the most promising PE-HD resin successfully to a slightly modified BOPP production line at Polivouga. By doing so, we have established a very cooperative partnership and are proceeding to further develop and optimise the HD-BOPE resins and film structures.”

Polivouga also brought a wealth of knowledge about flexible packaging to the partnership.  They understood ’what was needed for establishing added value, how you position it, and which materials can you replace’, explained Lightbody. Brückner’s process and stretching equipment expertise and Polivouga’s film manufacturing knowledge and capabilities also made it possible to rapidly validate product performance.

“The selection of our partners has really allowed us to enter the market and to move as quickly as we have. There were a great many innovations that needed to happen to bring this onto the market:  if it was only resin, if it was only the equipment, it wouldn’t be that strong a market adoption, but it’s everything together. We now have a total solution,” said Lightbody. “And that’s why it is really a story about collaboration.”

The result

Working together, the three companies were able to quickly develop HD-BOPE film technology and include the initial learnings in improved resins and new line designs.

“Running the film at Polivouga  and on Brückner's pilot line allowed us to optimise the resin, the equipment and the resulting film,” said Lightbody.

Polivouga can now produce 3 to 5 layer films.

“We have had the opportunity to test BOPE on our 5 layer lines with success. Using the wide range of Nova resins, BOPE has given us more flexibility in film design which allow us to meet our customer needs,” Barros said.

“For us, it wasn’t the first BOPE trial, but it was the first time that we tested high density BOPE. We are happy with the mechanical and functional properties results, which can be a very interesting solutions such PET replacement or downgauging in PE structures.”

The partnership is currently working on the third generation of film and developing additional grades optimised for a wide range of BOPE applications. The new grades have a broad orientation window and stiffness similar to BOPP. For Brückner, the project has led to a new line design, in which the necessary modifications were implemented.

Launched at K 2019, the new BOPP/BOPE Hybrid line, is optimised for full output BOPP as well as BOPE film production. The line had a working width of 6.6m and 8.7m and generated a huge amount of interest from existing BOPP film producers as well as converting companies.

“And while Brückner continues to make modifications to make BOPE as easy to run as possible, in January, a European company already purchased Brückner’s first hybrid line and further investments are expected in the short term,” Lightbody reported.

The development of the new film is a timely one. At last year’s K show, visitors  - from Europe, North America and elsewhere - to the Brückner booth were extremely interested in BOPE, due to its potential to provide a recyclable, monomaterial packaging solution.

“It is what the market is asking for. There’s been a huge push for monomaterial packaging  - we also call it Design for Recycling - with a number of brand owners who have come out with pledges to have 100% recyclable packaging,” said Lightbody.

“Everyone wants to implement the circular economy. It’s necessary – these are valuable materials, and we want them being reused as we do other materials. We are moving in the right direction.”

While this is the main driver, an additional advantage to oriented films is that, due to their properties such as stiffness and toughness, downgauging is real possibility.

“So material reduction is a huge advantage,” added Lightbody.

The biggest challenge

As Henry Ford allegedly once said: “Coming together is a beginning, staying together is progress, and working together is success." Owen Lightbody would agree. One of the biggest challenges in a collaboration project like this is the complexity of bringing everyone together – and the newness, he said.

“Newness, especially, is the hardest thing to overcome because of the obstacles that arise; but having this group together, our combined expertise meant that we learned together, we were able to solve problems quicker by working together and optimisation was more efficient by working together. I truly believe that without that strong collaboration we couldn’t have achieved what we did and how quickly we did it.”

And the pandemic of the past months? After K, the original idea was to have a number of promotional stand-up pouches ready for Interpack.  

“Right away, that put a milestone down,” said Lightbody. “We really got focused, put a schedule in place and we drove towards that target.”

With Interpack cancelled and travel restricted, it has been difficult. Trials have had to be postponed, as these need to be carried out together with the experts  - the process engineers, the extrusion engineer -  who understand the sheer complexity of the equipment and the process.

“So right now we’re still doing film evaluations, packaging evaluations, sampling, value chain partners, but really from the trial perspective, those are on hold. Hopefully we can resume these soon.”

However: “The next production run is already scheduled,” added Ruhland. “The target is to provide a stiff HD-BOPE film as printable base layer with good transparency.”

Transformative innovation Bringing a new material to market means welcoming in a new area of flexible packaging, said Lightbody, with evident enthusiasm.

“Transformative innovations like this don’t come along too often.”

“The BOPE development is a big project with a lot of efforts involved. We will continue this important collaboration for sure over the next years to provide completely new, recyclable BOPE films to the packaging market,” said Ruhland. Over and above that, however, was pride in the way this was achieved.

“It is truly a team accomplishment. Working with Diogo Barros, at Polivouga and Sebastian Ruhland, at Brückner, we forged an incredibly strong partnership and everyone’s brought their knowledge and expertise to the table to accelerate this development,” said Lightbody.

He concluded: “Through this collaboration we’ve advanced and developed a new material, and I am pretty sure that when we look back in a few years we’ll think: ‘Hey, we were part of the team that brought this new material to market’. To me, that’s pretty cool.”

Why is it only now possible to produce HD-BOPE, while BOPE has been made with LLDPE for some time now?

Traditional HDPE typically lacks the elasticity to be stretched to any extent while LLDPE is inherently easier, especially biaxially (in the machine and transverse direction). The resin technology that Nova Chemicals has developed enables a biaxial stretch ratio comparable to BOPP. The technical explanation is that LLDPE is more amorphous and has better elasticity which makes it much easier to stretch, while the higher crystallinity of HDPE makes it a much harder material to orient with a dramatically smaller orientation window compared to LLDPE.

What are the important properties for biaxial orientation of HDPE?

The desired properties of the film are stiffness, heat resistance, low tear and good optics. HDPE provides better heat resistance and stiffness which is why it is preferred over LLDPE. The key processing characteristics are extrusion output and reliable production with no film breaks. Achieving those requires low gel resins and a wide process window for orientation, which Nova’s solution phase resins are ideal for. Multilayer films have important barrier properties, with barrier layers that are often of a different material than the structural layers.

Does HD-BOPE offer the same performance?

As with many other flexible film applications, polyethylene offers a monomaterial solution for many applications that can’t be achieved with any other single polymer. BOPE is no different. While there are limitations to oxygen barrier performance of high-density polyethylene, HD-BOPE film structures can be metalized, coated with thin barrier lacquers or laminated to other polymers when necessary.

What is the advantage of HD-BOPE over BOPP?

The most significant benefit is easier recyclability. Many packaging applications require multiple materials to provide the required performance unless they utilize an all-PE film structure, especially due to the outstanding seal properties of PE. In addition, polypropylene is harder to recycle (due to lack of recycling streams) in some regions of the world including much of North America. Essentially, HD-BOPE is an important building block to help brand owners reach their packaging sustainability goals.

What about punctures and tears: is it as strong as BOPP?

HD-BOPE has comparable performance to BOPP including stiffness and toughness while demonstrating low tear for easy opening. What are the differences for the converter?  Film manufacturers such as Polivouga who produce HD-BOPE provide the convertor another building block to create monomaterial, recyclable flexible packaging. For example, a traditional mixed material laminate such as PET/PE can now be replaced with HD-BOPE/PE. Additionally, the enhanced properties of biaxially stretched film can allow converters to downgauge existing packages. The convertor will need to optimise their packaging lines as HD-BOPE will require new settings compared to BOPP or PET materials.

Can recycled material be used?

At this stage, recycled material is not being used in BOPE films.  Highly specialized resins that offer extremely low gels and lot-to-lot consistency are required due to the processability requirement for defect-free film. However, BOPE enables downgauging vs. blown film applications – another sustainability benefit. Besides this, recycled content can be incorporated into a blown-film partner web if the final structure is a laminate.

What about the price of HD-BOPE?

HD-BOPE is a high-value film for companies that are looking to advance the circular economy. However, it’s also a relatively new substrate for flexible packaging and time will tell how the pricing dynamics take shape. These are new times with new challenges and new drivers and it is through collaboration that the true value will be established.