Krefeld – “Green gluing” or “sustainable gluing” currently are buzzwords in the packaging industry. But what does sustainability mean? Not all of the UN’s Sustainable Development Goals or the Product Environmental Footprint (PEF) criteria can be fulfilled to the same extent. The objective is to find the best-possible compromise. In the public debate, however, some criteria are emphasised more than others and are weighted differently depending on respective interests. This leads to uncertainty and in some instances to contradictory assertions. Baumer hhs General Manager Percy Dengler and Business Development Head Thomas Walther shed some light on critical aspects of the issue.

How is Baumer hhs addressing the subject of sustainability?

Percy Dengler: At Baumer hhs, in its role as a packaging industry partner for industrial gluing applications, we ask ourselves the following questions, among others: How do we, our customers and our industry partners define the term “sustainability”? What impact does gluing have on the sustainability of packaging? Gluing is a core step of packaging production, but just one link in the value chain. From our perspective, the UN Sustainable Development Goal of “partnership” is among the most important, because working in partnership is the only way to establish the basic conditions for real sustainability. And that goes for packaging production, too. For this reason, we closely coordinate research activities with industry partners and customers to identify potentials for improving sustainability in packaging production. There’s no question about it: Sustainable gluing is the future.

Who do you collaborate with?

Thomas Walther: The Europe-wide 4evergreen initiative, for example, aims to ensure that fibre-based packaging makes a greater contribution to a circular, sustainable economy, while minimising impacts on the climate and environment. As a founding member, we are actively involved in achieving this goal. Other members of 4evergreen include Nestlé, Danone, Procter & Gamble, Westrock, AR Packaging, as well as numerous paper and paperboard manufacturers and recycling businesses. In other words, this alliance brings together organisations along the entire value chain. Baumer hhs is also active worldwide in bilateral collaboration projects with adhesive manufactures and customers. Our company is open to any partner interested in advancing sustainability.

Percy Dengler: We pursue the “rethink” approach, which means first deciding what is the right thing to do, and then doing it right. We want to rethink adhesive application. We are examining the subject comprehensively, and right now are in intense discussion on different levels with customers, industry partners and research institutions. As this shows, we are not “greenwashing” the issue by any means.

What are the most important aspects of your comprehensive approach?

Percy Dengler: The answer to the question of how industrial gluing can support the efforts of the packaging industry to increase sustainability is highly complex. A lot of things that appear to be sustainable at first glance, prove to be critical in the overall balance. You can only evaluate the sustainability of packaging if you take its entire life cycle into account. Unfortunately, the public debate often is dominated by isolated aspects that narrow the focus down to isolated sustainability criteria, which serve only the interests of isolated suppliers.

Changing the course of industrial gluing starts with developing bio-based, sustainable adhesives, developing a functioning circular economy, and further optimising and/or minimising glue consumption. Beyond that, we want to give our customers even more targeted support, helping them achieve maximum energy efficiency and avoid waste in their gluing processes. We have a long tradition of designing our equipment and solutions for optimised glue consumption, maximum energy efficiency and waste reduction. But we still see potential for further improvement. Conversely, bio-based adhesives and the development of a functioning circular economy are comparatively new issues for us. With this in mind, our aim is to scrutinise the entire value chain and critically question our own actions time and again.

What exactly are bio-based adhesives?

Thomas Walther: Today’s adhesives generally contain additives made of non-renewable fossil raw materials. One example is polymers, which are made from petroleum. In view of the growing global population and the worldwide rise in the demand for packaging, the packaging sector is called upon to resolve the conflict between growth and resource scarcity and to significantly improve the environmental footprint of its products and processes. Bio-based adhesives made from renewable raw materials can help.

What renewable raw materials are you referring to?

Thomas Walther: Examples include starch-based raw materials, natural resins, natural rubber and natural latex. From Baumer hhs’s point of view, however, it would be better to focus at least to some extent on biomass, meaning waste products from other processes or farming.

For example?

Thomas Walther: We see interesting potential in crop residues from grain production and other farming sectors, as well as in lignin, which is generated in large quantities in the paper and wood industries, ultimately as a waste product. Lignin is a carbon compound. Because of its specific properties, it has the potential to replace synthetic additives used in adhesives manufacturing.

What criteria determine whether a type of biomass is suitable for industrial adhesives?

Thomas Walther: There are many factors involved. For instance, adhesives made from biomass have to display the same application properties as conventional adhesives, so they don’t adversely affect packaging production by causing reduced output or higher reject rates, and thus more waste. Otherwise, sustainability would only exist on paper. Researchers therefore have to include the application properties in their analysis of bio-based adhesives from the outset. Baumer hhs does use starch-based adhesives in selected industrial segments. But they are not yet suitable for the high-speed machines used in packaging production. In a lot of cases, some of their properties simply are inadequate, for example they display low application quality, long setting times and insufficient gap filling. We conduct in-house research into the application and bonding properties of bio-based adhesives, and we are an active partner in research alliances.

Doesn’t starch come under the category of food?

Thomas Walther: Yes it does. So even when using sustainable raw materials, we have to weigh conflicting goals. Rising demand for starch could force up the price of specific food products. Rising demand for natural rubber could lead to clearing of the rainforest to make way for rubber plantations. Not only that, the cost of harvesting and transport, including the associated CO2 emissions, would have to be taken into account for adhesives based on natural rubber. Social issues would have to be another part of the analysis. Does a plantation economy threaten the supply of agricultural products to the local population? Does a plantation economy benefit the local population or just a few large landowners?

Percy Dengler: The basic conditions required to produce biomass are one factor that determines their sustainability. Working with our partners in industry, we base our evaluation of these raw materials on the economic, social and ecological criteria defined in the UN’s 2030 Agenda for Sustainable Development. We draw up a life cycle assessment (LCA) to assess their entire impact, including potential for goals that conflict with other areas. In other words, we take an in-depth look at this complex issue in order to achieve real sustainability in automated adhesive application.

Why is Baumer hhs, a manufacturer of industrial gluing solutions, working so intensively on sustainable adhesives?

Percy Dengler: Vigorous knowledge transfer between Baumer hhs and its partners in industry and research is a fundamental prerequisite for developing solutions that support industrial gluing with bio-based adhesives. Sustainability must go hand-in-hand with the demanding requirements the packaging industry and other sectors have when it comes to productivity, quality, reliability, flexibility and cost-efficiency. To ensure that it does, Baumer hhs works closely with adhesive manufacturers and research partners to develop adhesives. Our extensive know-how in industrial gluing is used to develop sustainable adhesives, and we in turn use the expertise of adhesive manufacturers to develop our gluing solutions. We adapt our equipment wherever necessary to achieve the necessary levels of productivity, quality, reliability, flexibility and cost-efficiency for our customers’ processes. The entire process must be geared towards sustainability if it is to earn the label “green gluing”.

Food packaging is associated with yet another important aspect: Some bio-based adhesives contain additives. The possibility of harmful substances migrating into the food has to be ruled out.

What is your opinion of regulatory measures such as the EU’s Plastics Strategy which, in line with the “polluter pays” principle, introduces extended producer responsibility for the environmental impact of packaging?

Percy Dengler: Baumer hhs welcomes such measures because they spur on progress. The market is putting pressure on the packaging industry to improve the reputation of its products. The industry has to make the manufacturing process for these products as eco-friendly as possible. And the packaging itself has to be as eco-friendly as possible. With our sustainability strategy, we want to support our customers as effectively as we can in their efforts to produce eco-friendly packaging. Eco-friendly packaging secures jobs in the packaging industry and in supplier companies.

And regulatory measures promote innovation. For example, in a very short time, we have received a surprising number of inquiries for machines capable of applying glue to produce paper-based straws and cups, which increasingly are replacing their single-use counterparts made of plastic.

How does biomass rate when it comes to cost-efficiency?

Percy Dengler: Adhesives made from biomass have to achieve a price/performance ratio comparable to that of conventional adhesives. In other words, adhesive manufacturing needs biomass that can be produced and made available in sufficient quantities. The petroleum-based raw materials used in the production of conventional adhesives are subject to price fluctuations, which would be largely eliminated in the case of sustainable adhesives. That would be another advantage of bio-based adhesives.

Do adhesives made from biomass offer advantages in terms of recycling?

Thomas Walther: Some manufacturers even advertise their bio-adhesives as being compostable. From Baumer hhs’s standpoint, however, the goal must not be to compost paper-based packaging, i.e. return it to the environment. Our goal is to recycle it, to establish a functioning circular economy in which packaging materials are automatically recycled, and in this way to minimise the impact of packaging on the environment. Conventional adhesives can have a negative influence on the recycling of paper-based packaging. This is particularly true of hot melt adhesives. End-of-line packaging specialists, for example, try to replace them with cold glues, which are easier to recycle.

Today, more and more hot melt adhesives based on biomass are appearing on the market. In view of sustainable gluing, it basically is a welcome trend. But here too, it’s important to analyse their impact on the recycling process. Regardless of what they are made from, hot melt adhesives have one thing in common: In waste paper processing and recycled paper manufacturing, they have a tendency to form sticky impurities, which can impair the quality of recycled paper grades and lead to costly disruptions in papermaking machines. Baumer hhs has already had some good experience with hot melt adhesives made at least in part from biomass. But there are still some unresolved issues.

The easier it is to recycle packaging, the less it costs to recycle it. Put another way, good recyclability improves the cost-efficiency of the packaging. What is more, good recyclability increases the rate of recovery of valuable fibre and helps meet the recovery targets of the EU’s Circular Economy Action Plan.

A while back you launched the GlueCalc smartphone app on the market, which packaging producers can use to minimise or optimise glue consumption. Isn’t minimising resource consumption the general goal in packaging production?

Percy Dengler: Yes, it is, and the industry is working on a broad front to achieve it. With GlueCalc, packaging manufacturers and end-of-line solution providers can just enter a few parameters to quickly and easily calculate on an order-by-order basis how much they can reduce glue consumption and CO2 emissions by switching from line to dot application. Many of our customers have reduced their glue consumption and CO2 emissions by 50% and more this way, which also means that the packaging they produce introduces less adhesive into the recycling process.

Our electromagnetic adhesive application heads offer the precision required to apply small dots of glue. What is more, they have a very long service life compared to electropneumatic heads. And that’s an important point: With electromagnetic application heads, there is no risk of high wear offsetting the ecological and economic advantages gained by cutting glue consumption.

In addition, the reliability of the equipment minimises waste in packaging production. And this is where our quality assurance systems come into play. They ensure our customers deliver 100% defect-free packaging products to their own customers. In short, to produce sustainable packaging – including automated adhesive application – all the various factors have to work hand-in-hand.

One of the primary goals of the Baumer hhs sustainability strategy is to minimise resource consumption. With the company’s GlueCalc app, packaging manufacturers and end-of-line solution providers can enter just a few parameters to quickly and easily calculate on an order-by-order basis how much they can reduce glue consumption and CO₂ emissions by switching from line to dot application. In practice, users achieve reductions of 50% and more.