Sustainable Packaging Brings Innovation Opportunities for Pressure-Sensitive Adhesives

When faced with supply chain disruptions that limited availability of an adhesive product, a company turned to ChemQuest to help solve the problem.

By Graeme Roan, Ph.D., The ChemQuest Group, Inc.

Sustainable Packaging Brings Innovation Opportunities for Pressure-Sensitive Adhesives

Product packaging is one of the many areas where consumer and brand-driven demands for more sustainable solutions are high. Packaging is obviously visible to consumers and is increasingly being perceived as ever-more wasteful. Minimizing the amount of packaging is a valid goal, but so too is creating smarter packaging that may offer greater recyclability and reuse, improved waste reduction, and the least amount of packaging while maintaining (or improving) performance.

Adhesives can play a key contributary role in making packaging more recyclable than it is today. Whilst various boxes and bottles are perceived as highly recyclable by many consumers, and the materials used to construct the box or bottle are indeed recyclable, the labels and tapes attached to them can diminish or even eliminate the full recycling potential.

Numerous types of adhesives are used across different packaging, including laminating adhesives, case and carton sealing hot melts, and many more. This article will focus on current technologies and future needs for pressure-sensitive adhesives (PSAs) in tape and label applications.

Labels Lead the Way

Several technologies in the label market have existed for several years and currently aid in bottle recycling. As already mentioned, the presence of an adhesive label on a bottle can cause limitations in recyclability. If that label could be easily removed on demand, however, it would represent a big advantage.

Unfortunately, a conventional removable PSA is not the answer here. Labels that rely on these PSAs can detach too easily during the product life cycle, which removes the brand identity as well as key product information. Instead, several adhesive manufacturers have developed technology that uses emulsion-based PSA products that can be washed off when the bottles are exposed to a warm caustic bath. Those clean bottles can then be fully recycled.

This technology has found limited (if any) utility in tape applications to date. The potential is there, however, especially with recent advancements in the performance of emulsion adhesives that make their performance more suited to many tape applications.

Another area of current innovation that started in the label world is liner recyclability. Significant industry-wide work is being done to look at recycling programs that will collect both used liner and matrix and explore ways to recycle it rather than discard it, which is common.

Products are also in use today that push technology forward in such a way that a liner is no longer needed at all; the roll of coated labels can be self-wound during manufacture and then dispensed for use without leaving any liner behind. These linerless labels are most prevalent today in various point-of-sale label printers, but broader opportunities exist. Standard packaging tapes are already self-wound, of course, but very few tapes used in other single-coated tape applications are.

Some of these enhancements and developments (such as the linerless constructions), whilst well-suited to many label applications, will inevitably see limited scope for utility in tapes. This is primarily due to many of the performance needs of those products, which align with the technology needs of the systems described previously as well as the utility of a single-coated tape.

Developing Sustainable Tape Technologies

Much work is being done to seek alternate ways of enhancing the sustainability of tapes used in packaging. Rather than focusing on removability, recycling, and waste reduction on the downstream end of the product’s life, these activities look upstream at sustainable enhancements in the creation of the tapes in the first place.

Reducing environmental emissions and energy use during adhesive coating can be achieved in many ways, all of which are currently viable to varying extents and being increasingly practiced by producers. Switching away from relatively low-solids, solvent-based adhesives is perhaps the main area of change, and there are various ways to do this whilst maintaining the performance needed.

Using 100% solids adhesives such as UV-curable hot melts has been talked about for many years, but with limited capability. The performance and use of these materials has improved significantly in the last decade, and these technologies can now achieve equivalent performance to solvent-based adhesives in many areas. Using UV cure removes the need for the long drying ovens and thermal oxidizers that consume significant energy. The floor space needed for the coating and curing equipment is also much smaller, and there is the potential for greater production speeds as well.

Environmental improvements can also be made by switching to the rapidly growing range of high-performance emulsion technology. This approach can produce adhesives with applicability far beyond the historical norm and conventional expectations of emulsion-based adhesives, moving their use comfortably into the arena of solvent-based systems.

Higher solids solvent systems have also emerged in recent years. These systems often encompass formulating and compositional innovations to allow the solids to increase whilst maintaining a workable viscosity for coating. In addition, they can achieve the needed tape performance through thermal cure in the drying oven and other means.

Continued Innovation

These are just some of the key areas for development that will enhance the sustainability of pressure-sensitive adhesives in packaging, allowing for waste reduction, greater recyclability, and lower energy use. Adhesives could further develop and change in additional ways as well, perhaps in collaboration with other manufacturers in the supply chain to create fundamentally new ways of using these types of materials. Regardless, adhesives have great potential for growth and innovation in support of sustainable packaging technologies now and into the future.