7 benefits of UV hot melt pressure sensitive adhesives: A game changer for adhesive applications

In the world of converting, manufacturers are constantly looking for innovations that push boundaries and make processes more efficient, cost-effective and environmentally friendly. Over the past few years, UV acrylic hot melt pressure-sensitive adhesives (PSAs), a technology offering reduced energy consumption, lower processing temperatures and negligible plant emissions, is beginning to see a belated breakthrough. Even though UV hot melt PSAs have been technically viable for nearly 40 years, reluctant converters have held them to single digit market share in comparison to traditional formulations which require drying or heat setting, such as water-borne, solvent-borne and rubber-based hot melt adhesives.

Unlike conventional liquid adhesives that rely on high temperatures and long, energy consuming thermal dryers to evaporate water or solvent carriers, UV hot melt PSAs utilise ultraviolet energy to immediately set the adhesive via a chemical reaction. The technology enables converters to produce a wide range of desirable tack and shear properties out of a single coating formulation simply by increasing or decreasing lamp output, leading to greater business opportunities for manufacturers willing to embrace the technology. In general, a UV hot melt process improves production efficiency, making it a viable and highly attractive alternative for many converters.

In this article we break down seven benefits that make UV hot melt pressure-sensitive adhesives stand out from more commonly used adhesive types.

1. Instant curing for faster production

One of the biggest advantages of UV hot melt PSAs is their ability to cure instantly under ultraviolet light. Unlike rubber-based hot melt adhesives that rely first on heating and then on cooling to set the adhesive, UV-curable adhesives pass underneath a compact UV curing assembly immediately after application to the web and harden in less than a second.

Instant curing decreases total web processing time which is beneficial in high-speed manufacturing environments as it reduces work in process and limits scrap, should an issue occur. Converters can evaluate the properties of the final product sooner, as the web does not have to go through long dryers or pass over a series of chilled rollers, resulting in less product waste.

Because there is no water or solvent to evaporate, UV hot melt completely eliminates the need for energy consuming thermal ovens as well as oxidisers or after burners in the case of solvents. This results in lower capital investments on new line purchases, reduces overall machine footprint, shortens set-up times, and eliminates process bottlenecks. The combined gains in efficiency result in higher overall profitability. The instant curing of UV hot melt pressure-sensitive adhesives presents a win-win for many converters.

2. Reduced energy consumption and lower application temperature

Rubber-based hot melt adhesives require high application melt temperatures while water and solvent-based adhesives rely on high temperature, energy consuming thermal dryers. Heating and then cooling hot melt as well as evaporating solvent and especially water carriers demand significant energy inputs. For many converters, higher energy costs were never a compelling reason to switch away from traditional methods, but the recent rise of global energy costs, energy supply constraints, and new scope emissions reporting has led many to reconsider alternatives. Those who do are discovering that UV hot melt PSAs take the big, energy sapping dryers, need for natural gas, and higher melt temperatures out of the equation.

Since UV hot melt PSAs are 100% solids, they contain no water or solvent carriers. As a result, thermal dryers that take time to heat, inadvertently release heat to the surrounding plant environment and burden the plant’s climate control system are not needed. UV hot melt PSAs also function at lower and safer melt application temperatures of 120 to 140°C (250 to 284°F) compared to rubber-based hot melt temperatures of 150 to 175°C (300 to 350°F). Because UV hot melt is crosslinked and not heatset like conventional hot melt, no additional chilled rollers are needed to cool the hot melt and web after the adhesive is applied. Compared to rubber hot melt and liquid adhesives, the overall process is more energy efficient.

By operating at lower temperatures, UV hot melt PSAs require less electricity for the drum/pail unloader, melt tank and heated hoses than rubber-based hot melts. The elimination of dryers for liquid adhesives means no natural gas is needed. Furthermore, reducing temperatures means less wear and tear on equipment, extended machinery lifespan, reduced maintenance costs, and a safer worker environment.

3. Exceptional bond strength and durability

UV hot melt PSAs, like solvent-borne adhesives, offer strong, long-lasting adhesion, ensuring that materials remain securely bonded over time and in a wide range of environments. The unique chemical reaction that occurs during curing creates a durable molecular structure, which provides improved resistance to heat, moisture and mechanical stress. Unlike rubber-based and water-based adhesives that weaken when exposed to certain environmental factors or have limited performance life, UV hot melt PSAs maintain structural integrity over time even under extreme conditions.

Because UV acrylic hot melt offers more durability than both rubber-based hot melt and water-based adhesives, it is an attractive alternative for converters looking to expand their current product line into more demanding markets. UV hot melt is unique in that increasing UV exposure decreases tack and increases shear. Likewise, decreasing UV exposure increases tack and decreases shear. This means converters can pursue a wider range of performance properties with fewer coating SKUs simply by adjusting UV output.

While UV hot melt may not be able to exactly match the performance properties of the most demanding solvent adhesives, it comes close. For many converters, the ability to adapt existing converting lines for UV hot melt offers an attractive option for less demanding solvent work, particularly if manufacturers are under pressure to reduce costs and improve sustainability throughout the manufacturing process whilst delivering similar performance properties.

4. Environmentally friendly with no harmful emissions

One of the standout features of UV hot melt PSAs is their eco-friendly composition. While UV hot melt is made in a similar manner to solvent adhesives, the hot melt solvents are stripped at the formulator’s production facility prior to shipping to the converter. Stripped solvents are retained and used again for the next batch of adhesive. By comparison, solvents in solvent-based adhesives are always shipped to the converter where they must be evaporated after application and then incinerated onsite.

As organisations throughout the supply chain are forced to report and then reduce scope 1, scope 2 and scope 3 emissions, it is important to note that UV hot melt emits none of the greenhouse gases (GHGs) reported under scope 1. In addition, it has a smaller environmental footprint as there are negligible volatile organic compounds (VOCs), hazardous air pollutants (HAPs), and toxic air pollutants (TAPs) released to the atmosphere during converting. Since UV hot melt does not require natural gas-powered drying ovens, oxidisers, or afterburners, converters are also able to reduce scope 2 emissions associated with the line.

Additional benefits of stripping the solvent prior to shipment are that the freight is no longer hazardous and converters do not need to ship as many adhesive drums or pails. This reduces scope 3 emissions related to diesel transport and saves converters money in shipping costs. By contrast, with liquid adhesives, the solvent component is necessary for applying the adhesive to the web; however, it is the converter who bears all expenses related to shipping, evaporating, and incinerating the solvents after application. Finally, because UV acrylic hot melt is solvent-free, workers are not exposed to toxic fumes, making for a healthier and safer workplace. Companies that use UV hot melt PSAs can more easily comply with environmental regulations while benefiting from a cleaner, more sustainable production process.

To learn more about this topic, read our article: 3 reasons why UV Hot Melt is more sustainable than Solvent-Based PSAs

5. Cost-effective and reduced material waste

Switching to UV hot melt PSAs results in lower operational costs and reduced material waste. Because these adhesives have a lower melt temperature than rubber-based hot melt and require no drying, they help businesses save energy costs over time. Since UV curing is instant, there is no need for extended drying or setting times which allows for greater production efficiency. Because the adhesive is supplied without a water or solvent-based carrier, which means less drums and less pails, freight costs and warehouse storage are reduced.

Another major cost-saving factor is the smaller production footprint required for UV hot melt adhesives. Unlike traditional liquid adhesive lines, which often require large tunnel dryers and additional ventilation systems, UV hot melt PSA lines take up significantly less space. This means manufacturers can operate in smaller facilities with lower overhead costs.

Because the web path is reduced due to instant curing, manufacturers experience less scrap and make-ready waste. This precise application process helps companies save money while maintaining consistent product quality.

6. Solvent recovery and reusability

As previously mentioned, a major advantage of UV hot melt PSAs over solvent-borne adhesives is that they allow for solvent stripping and reuse during production before shipment to the coater. This means formulators can recover and recycle the solvent, further reducing waste and improving material efficiency. This improves Scope 3 emissions for the converter.

Additionally, this recovery process supports a circular economy, where materials are continually reused rather than discarded. This feature makes UV hot melt PSAs a waste-reducing adhesive solution that aligns with modern sustainability practices.

Whilst solvent will undoubtedly remain the go-to adhesive solution for the most demanding, extreme environment applications, UV hot melt provides an attractive alternative for many others. UV hot melt offers converters the opportunity to manufacture many products with similar performance properties to solvent but without the costs and safety and environmental concerns associated with transporting it throughout the supply chain and then disposing it.

7. Versatile applications across industries

UV hot melt PSAs are widely used across various industries due to their fast curing, strong adhesion and eco-friendly properties. The ability of UV hot melt PSAs to offer a variety of tack and shear, depending on the UV dose, makes them the most versatile of the adhesive methods. Converters are increasingly embracing the technology for removable and permanent labels, packaging, tapes, graphics, industrial and automotive manufacturing, medical devices including dermal patches and body monitors, and building and construction products. Because of the high molecular weight, UV hot melt PSAs are also generally approved for food and skin contact applications.

The final performance properties of water, solvent and rubber adhesive are baked into the formulation. This means converters need to order and stock different SKUs to cover their full range of needs. With UV hot melt, the tackiness and shear can be altered by varying the UV dose. If dose increases, the shear strength goes up and the tack goes down; this option is brilliant on products such as wall hanging strips. The reverse of this where UV dose is lowered means that the applied adhesive becomes tackier with less shear strength; this type of product is best suited for packaging.

With such a broad range of uses, UV hot melt PSAs are a compelling solution for converters demanding flexibility, efficiency, durability and sustainability. By contrast, water-based adhesives are likely to continue being used for less demanding products that need to be produced with the lowest cost adhesive. Likewise, conventional hot melt, in use since the 1940s, is well accepted and entrenched. It certainly has its place. And similarly, the most demanding applications are likely to continue using solvent-borne adhesives, as the final properties offer the greatest performance. The important takeaway, however, is that when considering the four types of adhesive, UV acrylic hot melt is proving to be the most sustainable choice, and that is a game-changer that was not necessarily valued by converters just a few years ago.

Conclusion

UV hot melt pressure-sensitive adhesives, a proven technology that has been around for decades, are becoming a viable and increasingly preferred alternative for converters. This is because they offer instant cure, lower energy consumption, strong tack or shear and reduced environmental impact. Their ability to eliminate harmful emissions, reduce material waste and improve production efficiency is clearly driving new demand for UV acrylic hot melt.

As industries continue to prioritise eco-friendly solutions, UV hot melt PSAs stand out as a high-performance alternative to traditional adhesives across a number of applications.

To find out whether UV hot melt could be a viable option for your manufacturing process, contact GEW now: