Hot-melt adhesives were a big step forward for environmental sustainability and workplace safety, reducing employee exposure to toxic and flammable solvents.
Photo courtesy of Avery Dennison Medical.

Healthcare is always changing – new disease outbreaks, increases in various chronic conditions, paradigm shifts in delivery of healthcare – and through it all, adhesive medical materials have played a supporting role. Though not as renowned as the artificial heart or genetically engineered wonder drugs, adhesive developments have made a difference, particularly throughout the past 40 years, rising to meet patient needs and changing industry requirements.

Safety, sustainability

Sustainability is a front-and-center priority. Almost every business has sustainability objectives. From healthcare providers to medical device developers and their suppliers, each link in the supply chain is exploring different approaches. This encompasses manufacturing processes, raw material procurement choices, and fresh paths to patient care. The common goal: reduce impact on the natural environment.

For the medical adhesives industry, a keen focus on environmental issues traces back to the 1980s. The 1970s ushered in the U.S. Clean Air Act and the formation of the Environmental Protection Agency and Occupational Safety and Health Administration. By the ’80s, adhesive material producers faced a battery of new regulations intended to improve workplace safety and control emissions from toxic and highly flammable organic solvents.

As the scientific community’s knowledge about solvent toxicity grew, the level of residual solvents and other chemicals in products for human use or consumption became another big concern. Analytical testing capabilities for detecting residual chemicals made historic progress, and laboratory technologies became able to identify parts per billion of a substance in a sample. Many studies explored the toxic properties of different chemicals, with the main concern being cancer and how much exposure caused the disease.

As certain chemicals were flagged as carcinogenic or posing other serious risks, adhesive materials producers sought less-toxic alternatives. In addition, there were improvements in coater drying equipment to better capture emissions, recover solvents, and more efficiently dry materials to reduce residuals in finished products. But the most significant progress came with several major innovations, including:

  • Water-based adhesives
  • Ultraviolet (UV) and electron-beam cured adhesives
  • Hot-melt adhesives

Each of these developments represented a leap forward for adhesive safety, especially in reducing or eliminating solvent emissions and residual chemical risks. Today, there are families and sub-families of medical adhesives that trace their roots to these decades-old developments.

More recently, the medical materials industry has turned its attention to leachability risks of common compounds such as polyvinyl chloride (PVC), polyvinylidene chloride (PVdC), and plasticizers such as phthalates used to soften PVC. Medical barrier films, foams, and other materials free of these substances are becoming more important.

As material science evolves and the list of harmful chemicals grows longer, medical device developers and their suppliers continue the search for safer alternatives. This applies to chemicals used in raw materials and devices and those used in sterilization. In the 2000s, the EPA reported new evidence of health risks associated with ethylene oxide (EtO) sterilization. EtO has long been a preferred method for sterilizing adhesive-containing devices such as wound care dressings. Now, adhesive material suppliers and their customers are evaluating how products will tolerate different sterilization methods, such as X-ray irradiation and vapor phase hydrogen peroxide processes.

In the modern era, sustainability initiatives encompass the entire product life cycle. Leading corporations are embracing circular economics, in which they strive to eliminate waste and reduce their environmental footprint from a product’s inception to end of life. For medical adhesive materials suppliers, that includes finding ways to recover and recycle release liners.

Through a collaboration between Avery Dennison Medical and Eloquest Healthcare, this ReliaTect Post-Op Dressing with chlorhexidine gluconate is made of a transparent adhesive material offering antimicrobial, absorbent, and waterproof properties.
photo courtesy of Eloquest Healthcare

Game changers

In the past 40 years, two adhesive advances have had the most impact on wound care. One is hydrocolloids, which offer compelling technology for applications in which moisture management is crucial. They usually are rubber-based, pressure-sensitive adhesives (PSA) containing mixed particles, which allow PSA to absorb a significant amount of fluid. Those particles absorb fluid until they become saturated and form a soft, moist gel – making the dressing conducive to moist wound healing and atraumatic removal.

A second innovation that revolutionized wound care was the introduction of silicone-based adhesive dressings. Known for their gentle adhesion to the skin and equally gentle removal, soft silicone adhesives raised the bar for wound care. In particular, silicone-based wound care solutions improved care and quality of life for the elderly, whose fragile skin often struggles to heal and is susceptible to tears. They may also be ideal for neonatal/ pediatric patients, burn cases, and others with delicate or traumatized skin.

Hydrocolloids and silicones enabled significant advances for the wound care industry, improving patient comfort and promoting healing. Today, new generations of both materials continue to support wound management. There are thin silicone dressings 0.28mm thick designed to be flexible and conformable, and others capable of managing moderate to high wound exudate. Recently, hydrocolloids have been enhanced with the incorporation of additives, which may improve skin health, odor control, and pain levels. The list of additives that could further elevate the performance of hydrocolloids keeps growing.

Silicone-based adhesive dressings revolutionized when they were introduced. With their gentle adhesion and atraumatic removal, they remain a staple today for many wound care applications. In these two examples, soft silicone adhesives form a thin, conformable nonwoven dressing (left) and a highly absorbent foam dressing (right).
Photo courtesy of Avery Dennison Medical.

The next chapter

Photo courtesy of Avery Dennison Medical.

The 2000s mark the age of digital revolution and healthcare consumerization. Patients expect the same frictionless convenience from healthcare that they encounter in other facets of life, whether shopping, watching a movie, or catching a ride. It is the era of transformative care delivery models, as the industry devises new ways to diagnose, treat, and monitor patients outside of traditional settings – remotely, virtually, in less time, with fewer resources and at lower cost.

Medical devices and their materials must do more. For example, wearable devices are on the rise, and their performance requirements run the spectrum. Continuous glucose monitors might need to remain securely adhered for up to 28 days, throughout various daily activities. A drug injector might be worn on the skin for 15-to-30 minutes. Wear times for cardiac monitors or time-release medication patches could fall somewhere in between. There are skin-contact-layer adhesives specially designed for each use case, along with construction-layer adhesives to hold wearable components together.

Robust device requirements apply to more than wearables. Medical adhesives are going into new types of personal protective equipment (PPE), wound dressings, surgical applications, diagnostics and pharmaceutical innovations. New developments in each market serve multiple purposes. For example, Avery Dennison Medical’s BeneHold chlorhexidine gluconate (CHG) antimicrobial adhesive technology can be incorporated into thin, transparent dressings that offer clear site visualization and fight bacterial growth within the device.

Adhesive research and development parallels that of the broader materials landscape. New adhesives are designed to work in concert with next-generation fabrics, films, and other carrier materials, such as:

  • Soft, stretchable nonwovens
  • Materials with advanced wicking properties
  • Substrates enhanced with nanofibers
  • Novel composites and polymer blends
  • Special air-purifying filter media

For any new healthcare innovation to be adopted, there must be evidence to prove it performs as well as or better than its predecessor, usually at the same or lower cost. For adhesive materials suppliers, this means constant pressure to focus on a core trifecta:

1. Performance: Meeting functional requirements

2. Use: Enhancing patient experiences

3. Manufacturability: Cost- efficient, scalable production

Before 1980, healthcare providers did not have many adhesive material choices. By 2000, buoyed by hydrocolloid and silicone adhesive developments and others, they had an array of medical adhesives in their arsenals. Fast forward to today, and medical adhesive materials continue to support device innovations, from wound care to wearables. Furthermore, the sustainability movement of 40 years ago carries on with renewed intensity, driving the next chapters of innovation.

Avery Dennison Medical

About the authors: Deepak Prakash and Paul Saunders are senior director and senior manager, respectively, of global marketing for Avery Dennison Medical. They can be reached at deepak.prakash@averydennison.com or paul.saunders@eu.averydennison.com.