Current trends driving the adoption of UV LED curing technology

UV-LED-Curing-Technology

Stacy Hoge, Phoseon Marketing Manager, Excelitas Technologies

SUSTAINABILITY

All the major brands are requiring environmentally sustainable processes from printers and converters. These requirements significantly impact the developments for UV curing technology. The environmental benefits of UV LED curing are numerous. With traditional UV curing processes, the tremendous heat associated with mercury UV lamps required a lot of electricity to operate. Upgrading to UV LED curing can reduce energy bills up to 85 percent overnight with return on investment in well under one year.

On 6th March 2024, the U.S. Securities and Exchange Commission (SEC) voted three–two to adopt The Enhancement and Standardization of Climate-Related Disclosures for Investors. The rule requires all entities registered with the SEC to disclose climate-related information. This new SEC rule could be a major driver in the adoption of UV LED curing because the technology reduces scope emissions for manufacturers.

FLEXOGRAPHIC/DIGITAL INTEGRATION

Integrating flexographic and digital into one system is becoming a common trend in the printing industry. Hybrid industrial printing systems combine flexographic analog printing with inkjet printing on a single-pass production line. This setup leverages the benefits offered by both printing technologies. A combined flexo-digital printing system gives printers two production tools in virtually the same footprint.

UV LED curing easily supports both digital and flexographic processes, offering one technology for the whole print flow.

INDUSTRY 4.0 MANUFACTURING

We are now in the fourth industrial revolution, also referred to as Industry 4.0. Characterised by increasing automation and the employment of smart machines and smart factories, informed data helps to produce goods more efficiently and productively across the value chain. By collecting more data from the factory floor and combining that with other operational data, a smart factory can achieve information transparency and better decisions.

Customers increasingly require process control via real-time monitoring of UV LED curing lamps to better support Industry 4.0 manufacturing. Many of them are running “dark factories” that have no lights and no humans during processing, so 24 x 7 remote performance monitoring is key. Even in facilities with human operators, customers want to be notified about curing issues immediately to minimise down-time and scrap.

EXPANSION OF LOW MIGRATION INKS

As safety requirements of packaged food products with printed inks are becoming increasingly stringent, these strict requirements will drive the market trends. Expanded awareness pertaining to hazardous effects because of ink migration in food, cosmetics, pharmaceutical and cosmetic items will impact printing processes.

The popularity of low migration UV LED curable inks continues to grow and are expected to gradually replace the conventional UV inks.

The UV output of LED curing equipment is much more stable over time compared with conventional mercury-based systems. This results in greater process control when used to crosslink inks, coatings and adhesives in low-migration processes.

INCREASING PRESS SPEEDS

Due to increased press speeds, more power is required from the UV curing light source. Having enough power is crucial to the curing process. This is where peak irradiance and energy density (dose) come in to play. A

minimum threshold of irradiance is needed to start the polymerisation process and then a dwell time of dose is needed to finish the curing process. Both high irradiance and energy density are required for a successful cure.

Peak irradiance, also called intensity, is the radiant power arriving at the surface area and is instrumental in penetrating and curing the ink or coating. Peak irradiance can be affected by the output of the UV LED light source, the use of reflectors or optics to concentrate or contain the rays in a tighter surface impact area, and the distance of the source from the cure surface.

Energy density, also called dose or radiant energy density, is the measure of energy arriving at a surface per-unit-area during a defined period (called the dwell time or exposure time). A sufficient amount of energy density is necessary for full cure. Energy density is a factor of irradiance and exposure time and is managed by varying the speed or time that the substrate is under the UV LED lamp and the intensity of the light source.

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