What is UV acrylic hot melt?
UV acrylic hot melt is a 100% solid adhesive system that is applied to a substrate by heating the polymer until it reaches a coatable molten state. Unlike liquid adhesives, it contains no water or solvents, and has a lower application temperature compared to rubber-based adhesives.
The magic happens immediately after coating: the adhesive is exposed to ultraviolet (UV) light, which triggers a chemical reaction called cross-linking. This transforms the material from a simple melted plastic into a thermoset pressure-sensitive adhesive. By simply adjusting the intensity of the UV lamps, manufacturers can dial in specific properties, such as making the tape tackier or more heat-resistant, whilst using the exact same batch of raw material.
UV acrylic hot melts are emerging as an alternative to the three legacy technologies because they eliminate the need for massive, energy-hungry drying ovens.
Compared to rubber-based hot melts: While standard rubber hot melts are easy to process, they are thermoplastic, meaning they can melt again if they get too hot. Because UV acrylics are cross-linked by the UV lamps, they create a permanent chemical bond that resists high temperatures, chemicals, and aging far better than their rubber counterparts.
Compared to water-borne and solvent-borne: Traditional liquid adhesives require long, high-temperature ovens to evaporate the carrier (water or chemicals) to leave the adhesive behind. This process is slow, consumes massive amounts of energy, and, in the case of solvents, creates hazardous emissions. UV systems, by contrast, set instantly with light, allowing for a much smaller factory footprint and near-zero emissions.
Read our article 3 reasons why UV Hot Melt is more sustainable than Solvent-Based PSAs to find out more about why converters are choosing UV acrylic hot melt instead of other drying alternatives.
Pressure-sensitive adhesive applications
UV acrylic hot melt PSAs have many applications that suit the properties derived from the technology. The applications below are a few of the many where the durability offered by UV hot melt makes the technology ever- appealing to customers:
- Removable labels
- Permanent labels
- Resealable packaging
- Tapes
- Graphics
- Industrial / automotive
- Medical
- Building and construction
- Food and skin contact approved
UV hot melt webinar
In her webinar with Converting Quarterly magazine, GEW Inc’s Vice President, Business Development, Jennifer Heathcote, explains why UV acrylic hot melt has become a viable method for adoption, despite having a single digit market share since its commercial inception in the 1990s.
Features of UV acrylic hot melt
- No solvents in PSA
- solvents stripped by adhesive supplier during PSA production
- solvents reused in production of next batch
- Lower melt / application temperature
- rubber ≈ 150 to 175C (300 to 350F)
- UV ≈ 120 to 140C (250 to 284F)
- All-electric operation / no hydrocarbons
- 100% solids, chemical reaction
- No emitted GHGs, VOCs, HAPs, TAPs, FOG
- Smaller equipment / processing footprint
- More rigid, harder, less soluble, more thermally stable properties
Benefits of UV acrylic hot melt
- Reduced shipping weight, shipping frequency, storage space
- Workers not exposed to solvent fumes
- No explosion risk
- No thermal ovens, oxidizers, afterburners, emissions permits
- Reduced scope 3 emissions
- Reduced energy requirements
- Reduced scope 2 emissions due to lower energy requirements
- Lower cost of operation
- Increased operator health and safety
- Complies with all-electric sustainability targets
- No carriers to flash-off, incinerate, or release to atmosphere
- Reduced capital equipment investment
- Increased operator health and safety
- No scope 1 emissions
- Less floor space, less scrap, less make ready
- More robust end use properties compared to water/rubber PSAs
- Environmentally friendly alternative to many solvent PSAs
Alternatively, read our article that outlines 7 benefits of UV hot melt pressure sensitive adhesives.
Specifying UV for acrylic hot melt PSA lines
- NUVA2 or E4C can be specified on a PSA line, with 1 to 8 lamp heads typical of many installations.
- Arc lamps sized 100mm greater than coat width
- Lamps mounted to press chilled roller preferably
- Paper and some films can be straight through web path
- Emitted UVC energy density must match required hot melt energy density for coat weight and max targeted web speed
- More UVC needed for thicker coat weights and faster web speeds
- If no confirmed specification, use 1.2 mJ/cm2 UVC / GSM
To learn how to confirm your PSA coating line with UV hot melt, speak to our sales team now.
GEW products of UV acrylic hot melt
NUVA2
NUVA2 is the most effective UV curing system for wide web coating and specialist industrial applications. Fully air-cooled up to 250cm and available up to 27kW total lamp power, NUVA2 is available with a wide range of customisation and integration options.
GEW’s patented reflectors are actively cooled to ensure that heat transfer to the substrate is minimised, whilst delivering the highest UV intensity and dose available. The quick-change cassette design ensures fast lamp changes with only 1 hex key tool required and the innovative spherical lamp ends prevent breakages on long lamp changes.
Reliability is guaranteed and when powered by GEW’s RHINO system, NUVA2 can be purchased with a 5 year warranty which means no unplanned maintenance costs well beyond the return on investment period.
DoseGuard
DoseGuard consists of a scanning optic (ICAD® unit) mounted underneath the lamp, which continuously measures the UV light that reaches the substrate, across the entire width of the system. It improves the UV curing process by automatically adjusting the power of your GEW UV lamps to maintain a target UV dose.
DoseGuard can be set to scan each UV lamp array individually, reporting any imperfections in UV output across the entire width.
For UV acrylic hotmelt PSA applications, it is vital to deliver the correct dose of UV, in order to produce the correct levels of tack or sheer required for the product being produced. DoseGuard guarantees the UV dose is kept within the converter’s desired range, minimising waste and improving product quality.
Case studies
An example of a customer that switched their PSA coating line to UV acrylic hot melt is Nu-Coat, from the Welsh Valleys. Nu-Coat installed GEW’s NUVA2 on their Elite Cameron line, via Tim Self at TS Converting. The machine is specially configured to employ three UV lamps across three of its four lamp head bays, with the fourth bay used in situations where they need additional power.
Watch the case study video below.
Speak to our Sales team
To upgrade your PSA coating line to UV acrylic hot melt, contact our Sales team now:
Region, International:
Marcus Greenbrook
Director, International Sales
Email Marcus directly
Region, Americas:
Jennifer Heathcote
Vice President, Business Development
Email Jennifer directly
