As the push toward sustainability continues, demands for greater accountability and long-term environmental commitments have targeted most, if not all, manufacturing industries. The chemical sector is no stranger to these added pressures or expectations. Fortunately, many in the adhesives and sealants market consider such sustainable strategies and stricter regulations a necessity — and have for some time.
In 2011, for example, Together for Sustainability (TfS) launched as a chemical company initiative to assess, audit, and improve sustainability practices within global supply chains. It partnered with EcoVadis to provide these assessments via scorecards. The EcoVadis methodology covers 21 criteria across four themes: the environment, sustainable procurement, ethics, as well as labor and human rights.
A greater number of chemical companies are also conducting product testing to measure carbon properties. For instance, Ingevity Corporation recently asked consulting firm Environmental Resources Management to determine the carbon-negative properties of the pine-based raw materials found in Ingevity’s WestRez 5101 tackifier adhesive. WestRez 5101 is ideal for packaging, tapes, labels, and construction adhesive applications.
The result: it completely offset the volume of greenhouse-gas emissions produced during manufacturing, generating a carbon footprint 12% lower than that of the petroleum-based alternatives.
Nevertheless, progress takes time. Several adhesives in use today still use fuel-based raw materials and plastics, which are harmful to the environment. Developing products that offer acceptable application and cure times, ensure reliable bonds with longevity, and meet toxicity and flammability requirements is undoubtedly challenging.
This is particularly true while complying with environmental regulations, such as limiting volatile organic compounds or VOCs. VOCs are substances often used in manufacturing adhesives and sealants, which are emitted as gases that contribute to the formation of ground-level ozone with the potential to cause adverse health effects.
The low VOC adhesive market is comprised of adhesives that offer little to no off-gassing — meaning it is possible to make better choices and successfully innovate. In fact, this is what much of the adhesives industry is continually working on: innovation.
According to a report from The Freedonia Group, adhesive and sealant manufacturers, globally, are increasingly focusing on producing products that reduce their carbon footprint and that of their end-users. And as demands increase for more sustainable products, so will the R&D that brings formulas that are naturally derived and include recyclable materials. Fortunately, there are a few ways adhesives can be manufactured in a way that’s healthier for the environment.
Make them biodegradable
Pre-pandemic, Boston University (BU) researchers developed an adhesive formula that naturally degrades after use.
To be labeled biodegradable, adhesives must be made from natural substances that are formulated to break down into carbon dioxide (CO2), water, or other natural gases through bacteria and other micro-organisms. The main ingredient in the formula created by the BU team is carbon dioxide.
According to an article on the BU website: “This polymeric adhesive system, composed of environmentally benign building blocks, implements carbon-dioxide sequestration techniques, poses minimal environmental hazards, exhibits varied peel strengths from scotch tape to hot-melt wood-glue, and adheres to metal, glass, wood, and Teflon surfaces.” (Read more here).
Although CO2 is typically considered a pollutant in large volumes, in this case the adhesive material repurposes carbon dioxide that would otherwise go into the atmosphere. The formula can be adapted for several industrial and medical applications, meaning it’s safe to use on skin. There is also a potential for oil refineries or production plants to repurpose the gas for environmentally friendly polymers, say the researchers.
The need for biodegradable options for medical use (such as wound care) is significant, finds a study by ResearchAndMarkets. In this case, pressure-sensitive adhesives (PSAs) that decompose naturally, are ideal. PSAs adhere with the application of pressure, requiring no solvent or heat for activation. Currently, cyanoacrylate adhesive is commonly used as a tissue sealant, but it’s non-biodegradable and can cause an allergic reaction in some individuals.
Medical tapes are also often manufactured using solvent-based polymers. When the solvent evaporates, the polymers harden into an adhesive — but the byproducts are burned, creating unnecessary pollutants. Global conglomerate, 3M, has a Medical Solutions Division that’s been committed to developing tapes and dressings that are manufactured without the use of solvents and, instead, use hot-melt or water-based adhesives.
For the labeling and packaging industry, biodegradable options are advancing quickly. Water-based BioTAK S100 is one example of a completely biodegradable and compostable adhesive, developed by Sustainable Adhesive Products B.V. The BioTAK formula is also approved for direct food contact, such as the small labels found on produce.
Use bio-based materials
Rather than relying on conventional fossil-based raw materials, bio-based adhesives and sealants use, at least in part, renewable materials. These typically include starch, cellulose, proteins (such as casein), vegetable oils, lignin, or natural resins.
Global adhesives provider, H.B. Fuller, recently announced that it has been working with one of the world’s largest polymer suppliers, Covestro, to deliver an adhesive with a reduced climate impact for the automotive, textiles, woodworking, and composites industries.
“We believe that any way CO2 emissions can be reduced should be embraced, no matter how small, because many small steps can add up to a strong economy of scale and a giant leap forward for the adhesives industry,” shared Iñaki Sigler, H.B. Fuller’s global product manager for the Woodworking and Composites division, in a recent statement.
According to H.B. Fuller — which has completed the EcoVadis assessment every year since 2015 — the new ingredient is a bio-attributed raw material that will replace a proportion of fossil-based raw materials. The mass-balanced polyurethane material will be used in a reactive hot-melt adhesive and is ISCC-PLUS certified, which is a sustainability certification program for bio-based and recycled raw materials.
By gradually converting its production to alternative raw materials, Covestro aims to replace fossil materials and make its value chains more sustainable.
“We see this new, strategic product development as an investment in all our futures and a commitment to a more sustainable world,” said Dr. Thorsten Dreier, head of Coatings and Adhesives at Covestro.
Today, it’s not uncommon for the hot-melt formulas used to incorporate a target of about 50% bio-based raw material, at least in the packaging industry. The problem with surpassing this percentage has typically been production concerns, such as slower line speeds or shorter equipment cleaning cycles.
Late last year, global chemical company Henkel released an innovative hot-melt solution that captures CO2 emissions. Technomelt Supra ECO is the first carbon-negative, hot-melt made with a high portion of bio-based material. In fact, Henkel’s scientists were able to develop a formula that exceeded more than 80% of bio-based raw material input without losing performance.
“As we had a very close look at the values we can deliver, we found out that our solutions are not only able to reduce CO2 output during procurement and production but, furthermore, bind CO2 if you look at the overall balance for the global warming potential in 100 years,” said Sergio Mattos, head of Product Development, North America at Henkel. “We were very happy when we saw the results of the calculations — a negative cradle-to-gate product carbon footprint is the best possible outcome.”
Henkel’s manufacturing plants and processes are certified by the International Sustainability & Carbon Certification, which ensures traceability of bio-based material throughout the supply chain and assures its sustainable sourcing.
Choose compostable or repulpable
As the demand for compostable packaging is increasing, so is the need to switch to compostable labels and the adhesives that bond these labels.
Compostable adhesives can be considered as a type or sub-set of the biodegradable options. However, they’re eventually broken down as compost and work in a waste-remediation system. Ideally, these formulas leave no harmful residue or waste behind once fully composted — and result in compost that can later be used to enhance or fertilize soil.
In the U.S., the Biodegradable Products Institute is responsible for officially certifying a product as compostable. To be certified, at least 90% of the adhesive must decompose after 90 days into CO2 and water vapor. The remaining portion of the adhesive must not impair the quality of the compost soil.
Materials science and manufacturing company, Avery Dennison, offers a biodegradable portfolio with S9500, a compostable range with “facestock and adhesive combinations that can be reintroduced into nature.” The S9500 adhesive was awarded the “OK Compost” certificate and is recognized as biodegradable and compostable.
Another Avery Dennison product from its Label and Packaging Materials division is TrueCut All-Temp Adhesive Technology, AT2550, which was purpose-built for paper facestocks in shipping, warehouse, and logistics applications. Significantly, AT2550 is also repulpable, meeting the testing criteria of the Tag and Label Manufacturing Industry (TLMI) Recycling Compatible Adhesive LRP-2 Lab Test Protocol, which confirms an adhesive is fully recycled at a label’s end-life.
Repulpable adhesives completely dissolve in water during paper repulping operations without leaving a contaminating residue behind. They’re by far one of the most sustainable glue options.
It’s possible to develop and manufacture more sustainable adhesives and sealants that support climate-change efforts, but this requires modification of existing products and new innovative technologies. Fortunately, many in the industry have taken steps to do just that.
Engineers often struggle to obtain accurate engineering data on tapes and adhesives to effectively run simulations — this results in excess material waste and additional prototyping cycles, which hinders sustainability efforts.
In response to this challenge, 3M and Ansys have collaborated to create an industry material modeling training program that teaches engineers how to employ simulations with tape and structural adhesives to optimize adhesive and joint design, decrease waste, and improve production efficiency.
“Engineers can significantly reduce costly material waste and help power team-wide environmental sustainability by mastering a rapid and robust solution that helps determine the optimum adhesive and joint design for bonding applications,” shared Shane Emswiler, senior VP at Ansys.
The Ansys Learning Hub courses are taught by 3M research scientists, with live and virtual workshops offered here.