Sean Milmo, European Editor10.01.15
The days of traditional mercury vapor UV lamps, which were first introduced around 130 years ago, may be numbered in Europe because of the European Union’s health and safety legislation.
However, UV LED technologies have grown and been improving so rapidly that they appear capable of taking over as a viable, safer alternative.
After being a niche application only a few years ago, UV LED could account for as much as 30% of the market by next year, according to Yole Developpement, a consultancy in Lyons, France. This is despite complaints from printers about the inadequacies of LED equipment and inks – at least in printing processes like flexography and web offset.
The main problem has been the availability of a restricted range of photoinitiators and LED being limited to applications within a narrow range of UV wavelengths.
LED vs. Mercury Vapor
While LED technologies have become far more popular in recent years, the use of mercury vapor lamps has also been growing quickly, so that a large proportion of printers now use traditional UV systems.
However, mercury has increasingly been regarded by the authorities as a substance whose use had to be phased out as quickly as possible because of its high level of toxicity.
Its continued presence in UV curing lamps is threatened by three pieces of EU legislation. These are two amended directives on Restriction of the use of certain hazardous substances in electrical and electronic equipment (RoHS 2) and on Waste Electrical and Electronic Equipment (WEEE 2).
The third is the eight-year-old regulation on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH). Under the EU’s legislative system, directives set objectives, which must be incorporated into the laws of the 28 member states, with each deciding how the aims should be achieved within their territories.
Regulations, on the other hand, are binding legislative acts, which must be applied in their entirety by all member states.
Currently, with respect to the future of UV mercury lamps, the key legislation is the amended RoSH 2 directive, which aims to phase out the use of mercury but with some exemptions, due to come into effect in July next year.
These include some forms of specialist lighting and mercury equipment in what is called, in the text of an annex to the legislation, large-scale stationary industrial tools (LSSIT) or large scale fixed installations (LSFI).
In the printing sector, the European Commission, the Brussels-based EU executive, has given as an example of a LSFI or LSSIT newspaper presses, which do not usually use UV curing systems. The Commission has yet to make clear whether smaller printing plants or commercial printing units with, for example, digital presses doing wide-format work, can be classified as being “large-scale.”
Manufacturers of UV mercury lamps and their trade associations in Europe argue that the equipment should be classified as being an LSSIT wherever it is used. The lack of a clear definition of what is “large-scale” and “stationary” may mean that equipment may have to be categorized for exemption on a case-by-case basis.
The Commission is under pressure from NGOs, certain EU member states and members of the European Parliament (MEPs) to take a hard line on exemptions.
The Brussels-based Zero Mercury Working Group (ZMWG), which strives for zero supply, demand and emissions of mercury, is supported by 95 NGOs from more than 50 countries, a large proportion of them in Europe.
“We don’t like the idea of exemptions,” said Elena Lymberidi-Settimo, zero-mercury project coordinator at the European Environmental Bureau (EEB), a founder of ZMWG. “The lack of clarity on the exemptions creates a lot of loopholes, which enables producers and users to escape their responsibilities.
“LED UV technologies have been much improved in recent years,” she continued. “The excuse that there are no acceptable replacements for UV mercury lamps seems no longer to be valid.”
Opponents of exemptions are even more hostile to their being granted for long periods or even without any time limit, which some industry groups are reported to be requesting.
“The existence of LED alternatives and the certainty that LED technologies will soon reach or exceed the same levels of performance as UV mercury lamps makes exemptions without time limits completely unjustified,” said Lymberidi-Settimo.
REACH Takes Aim at Mercury Systems
The uncertainties about the regulatory future of UV mercury systems is being compounded by the possibility that provisions of the RoSH2 legislation will be superseded by action under REACH. RoSH is mainly responsible for protecting the health of workers and end-users, while the main task of REACH is the protection of the environment from hazardous substances.
The involvement of REACH could mean that due to mercury being so toxic, its use in UV lamps will have to be authorised through the Helsinki-based European Chemicals Agency (ECHA) for a certain number of years after which it would have to be phased out.
Much of the impetus behind the continued strong demand for curing by UV mercury lamps has in fact been its environmental benefits, as well as its ability to provide greater gloss, more resistance to abrasion and chemicals and more durability. Traditional UV curing is solvent-free and emits little or no volatile organic compounds (VOCs).
The amount of energy used to cure inks with UV mercury lamps is still relatively high, but much less than that needed to dry solvent or heatset inks. The instant curing results in a much faster workflow and higher productivity.
However, traditional UV has a number of long-standing disadvantages. In addition to the dangers of its use of mercury, the lamps can emit ozone, although this health hazard has been considerably lessened by development of filters to remove ozone from the production area.
In addition, the lamps take time to reach full power once they are switched on. A minimum light intensity must be maintained while they are operating, otherwise their curing capacity will be restricted. This can result in the lamps radiating a lot of excess energy so that on average they are less than 15% energy efficient.
These weaknesses have enabled UV LED to become more competitive. It does not have any major safety worries like mercury or ozone emissions. LED lamps come into operation immediately once they are turned on. As is the case with mercury lamps, they need to be cooled by water or other means.
The energy consumption of UV LED is approximately 20% to 30% that of the mercury system. As a result, its power output is weaker, but this can be compensated for by a more intense and targeted cure.
A restricted choice of raw materials for LED lights and for photoinitiators cause the LED equipment and accessories to be considerably more expensive than traditional UV, although this is partly offset by relatively low operating costs.
In terms of print quality, UV LED has been making so much progress that on many aspects it on a par with traditional UV. A major bonus is that due to its lower temperature, it can be applied to heat sensitive substrates, such as plastics.
UV LED Inks
The development of UV LED inks, in addition to the lamps, has been contributing a lot to the fast growth of the curing system. Inks with additives like amines, ethers and silanes have been helping to tackle the problem of oxygen inhibition in UV LED, which restricts the surface cure of inks and coatings.
A variety of photoinitiators have had to be introduced to deal with the concentrated narrow spectral light emissions of LED systems.
The more successful and energy efficient UV LED becomes, the bigger the doubts will be about the future of UV mercury systems. Sales of LED equipment and inks have been boosted by a booming UV market in Europe, but they have also been driven substantially by a need among printers to be able to use an alternative to mercury curing.
“Thanks to this (desire for a replacement), an overall LED market that represented only around $20 million in 2008 grew to $90 million in 2014 at a compound annual growth rate of 28.5%,” said Pars Mukish, business unit manager, LED, at Yole Development.
This fast growth will continue into the next decade, so that by 2019, the UV LED business will increase to $520 million, according to Yole.
The LED expansion will be helped by the increasing availability of hybrid curing systems combining UV LED and traditional UV on the same presses.
This is expected to assist UV LED in making greater inroads into the flexo and web offset sectors, in which is has a lesser presence than in UV inkjet.
Access to hybrid solutions will enable printers to switch more easily from mercury curing to UV LED. Printers should also have the attraction of cheaper costs for UV LED equipment, which is expected by Yole to expand into markets outside printing, such as disinfection, horticultural lighting and biomedical devices.
At the same time, considerably more companies have entered the sector to make LED equipment and consumables like inks, which will put further downward pressure on prices.
Printers may be worried that as new entrants move into the production sector for UV LED systems, there will be a rush among equipment and component manufacturers, maintenance specialists and even ink producers to leave traditional UV. This could be the inevitable outcome of a transition from one dominant technology to another.
European Editor Sean Milmo is an Essex, UK-based writer specializing in coverage of the chemical industry.
However, UV LED technologies have grown and been improving so rapidly that they appear capable of taking over as a viable, safer alternative.
After being a niche application only a few years ago, UV LED could account for as much as 30% of the market by next year, according to Yole Developpement, a consultancy in Lyons, France. This is despite complaints from printers about the inadequacies of LED equipment and inks – at least in printing processes like flexography and web offset.
The main problem has been the availability of a restricted range of photoinitiators and LED being limited to applications within a narrow range of UV wavelengths.
LED vs. Mercury Vapor
While LED technologies have become far more popular in recent years, the use of mercury vapor lamps has also been growing quickly, so that a large proportion of printers now use traditional UV systems.
However, mercury has increasingly been regarded by the authorities as a substance whose use had to be phased out as quickly as possible because of its high level of toxicity.
Its continued presence in UV curing lamps is threatened by three pieces of EU legislation. These are two amended directives on Restriction of the use of certain hazardous substances in electrical and electronic equipment (RoHS 2) and on Waste Electrical and Electronic Equipment (WEEE 2).
The third is the eight-year-old regulation on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH). Under the EU’s legislative system, directives set objectives, which must be incorporated into the laws of the 28 member states, with each deciding how the aims should be achieved within their territories.
Regulations, on the other hand, are binding legislative acts, which must be applied in their entirety by all member states.
Currently, with respect to the future of UV mercury lamps, the key legislation is the amended RoSH 2 directive, which aims to phase out the use of mercury but with some exemptions, due to come into effect in July next year.
These include some forms of specialist lighting and mercury equipment in what is called, in the text of an annex to the legislation, large-scale stationary industrial tools (LSSIT) or large scale fixed installations (LSFI).
In the printing sector, the European Commission, the Brussels-based EU executive, has given as an example of a LSFI or LSSIT newspaper presses, which do not usually use UV curing systems. The Commission has yet to make clear whether smaller printing plants or commercial printing units with, for example, digital presses doing wide-format work, can be classified as being “large-scale.”
Manufacturers of UV mercury lamps and their trade associations in Europe argue that the equipment should be classified as being an LSSIT wherever it is used. The lack of a clear definition of what is “large-scale” and “stationary” may mean that equipment may have to be categorized for exemption on a case-by-case basis.
The Commission is under pressure from NGOs, certain EU member states and members of the European Parliament (MEPs) to take a hard line on exemptions.
The Brussels-based Zero Mercury Working Group (ZMWG), which strives for zero supply, demand and emissions of mercury, is supported by 95 NGOs from more than 50 countries, a large proportion of them in Europe.
“We don’t like the idea of exemptions,” said Elena Lymberidi-Settimo, zero-mercury project coordinator at the European Environmental Bureau (EEB), a founder of ZMWG. “The lack of clarity on the exemptions creates a lot of loopholes, which enables producers and users to escape their responsibilities.
“LED UV technologies have been much improved in recent years,” she continued. “The excuse that there are no acceptable replacements for UV mercury lamps seems no longer to be valid.”
Opponents of exemptions are even more hostile to their being granted for long periods or even without any time limit, which some industry groups are reported to be requesting.
“The existence of LED alternatives and the certainty that LED technologies will soon reach or exceed the same levels of performance as UV mercury lamps makes exemptions without time limits completely unjustified,” said Lymberidi-Settimo.
REACH Takes Aim at Mercury Systems
The uncertainties about the regulatory future of UV mercury systems is being compounded by the possibility that provisions of the RoSH2 legislation will be superseded by action under REACH. RoSH is mainly responsible for protecting the health of workers and end-users, while the main task of REACH is the protection of the environment from hazardous substances.
The involvement of REACH could mean that due to mercury being so toxic, its use in UV lamps will have to be authorised through the Helsinki-based European Chemicals Agency (ECHA) for a certain number of years after which it would have to be phased out.
Much of the impetus behind the continued strong demand for curing by UV mercury lamps has in fact been its environmental benefits, as well as its ability to provide greater gloss, more resistance to abrasion and chemicals and more durability. Traditional UV curing is solvent-free and emits little or no volatile organic compounds (VOCs).
The amount of energy used to cure inks with UV mercury lamps is still relatively high, but much less than that needed to dry solvent or heatset inks. The instant curing results in a much faster workflow and higher productivity.
However, traditional UV has a number of long-standing disadvantages. In addition to the dangers of its use of mercury, the lamps can emit ozone, although this health hazard has been considerably lessened by development of filters to remove ozone from the production area.
In addition, the lamps take time to reach full power once they are switched on. A minimum light intensity must be maintained while they are operating, otherwise their curing capacity will be restricted. This can result in the lamps radiating a lot of excess energy so that on average they are less than 15% energy efficient.
These weaknesses have enabled UV LED to become more competitive. It does not have any major safety worries like mercury or ozone emissions. LED lamps come into operation immediately once they are turned on. As is the case with mercury lamps, they need to be cooled by water or other means.
The energy consumption of UV LED is approximately 20% to 30% that of the mercury system. As a result, its power output is weaker, but this can be compensated for by a more intense and targeted cure.
A restricted choice of raw materials for LED lights and for photoinitiators cause the LED equipment and accessories to be considerably more expensive than traditional UV, although this is partly offset by relatively low operating costs.
In terms of print quality, UV LED has been making so much progress that on many aspects it on a par with traditional UV. A major bonus is that due to its lower temperature, it can be applied to heat sensitive substrates, such as plastics.
UV LED Inks
The development of UV LED inks, in addition to the lamps, has been contributing a lot to the fast growth of the curing system. Inks with additives like amines, ethers and silanes have been helping to tackle the problem of oxygen inhibition in UV LED, which restricts the surface cure of inks and coatings.
A variety of photoinitiators have had to be introduced to deal with the concentrated narrow spectral light emissions of LED systems.
The more successful and energy efficient UV LED becomes, the bigger the doubts will be about the future of UV mercury systems. Sales of LED equipment and inks have been boosted by a booming UV market in Europe, but they have also been driven substantially by a need among printers to be able to use an alternative to mercury curing.
“Thanks to this (desire for a replacement), an overall LED market that represented only around $20 million in 2008 grew to $90 million in 2014 at a compound annual growth rate of 28.5%,” said Pars Mukish, business unit manager, LED, at Yole Development.
This fast growth will continue into the next decade, so that by 2019, the UV LED business will increase to $520 million, according to Yole.
The LED expansion will be helped by the increasing availability of hybrid curing systems combining UV LED and traditional UV on the same presses.
This is expected to assist UV LED in making greater inroads into the flexo and web offset sectors, in which is has a lesser presence than in UV inkjet.
Access to hybrid solutions will enable printers to switch more easily from mercury curing to UV LED. Printers should also have the attraction of cheaper costs for UV LED equipment, which is expected by Yole to expand into markets outside printing, such as disinfection, horticultural lighting and biomedical devices.
At the same time, considerably more companies have entered the sector to make LED equipment and consumables like inks, which will put further downward pressure on prices.
Printers may be worried that as new entrants move into the production sector for UV LED systems, there will be a rush among equipment and component manufacturers, maintenance specialists and even ink producers to leave traditional UV. This could be the inevitable outcome of a transition from one dominant technology to another.
European Editor Sean Milmo is an Essex, UK-based writer specializing in coverage of the chemical industry.