Reduced plate thicknesses, recycling of solvents and the use of efficient equipment and washout solvents are making real progress in the field of climate protection and offer a range of advantages over introducing alternative processing methods

The demands for increased climate protection may well currently seem a world away from many packaging printers' day-to-day business, however, in the long term, they too will have to react to the increasing, public pressure. Already in today's industry, brand owners, trade chains and large packaging companies are setting high goals in terms of environmental compatibility, which they document, for instance, through public campaigns, self-imposed commitments or memberships to ecologically motivated non-profit organizations. In the future, all of the companies involved in the entire packaging manufacturing process are expected to not only assume responsibility for the safety of their own products, but also for the impact they have on the environment. The flexographic printing industry is no exception here, and even a production step such as the manufacturing of flexographic printing plates, which represents a comparably low proportion (typically under one percent) of the finished packaging, can make a contribution towards lowering CO2 emissions. Based on an analytical evaluation of the two alternative, conventional processes, Flint Group Flexographic Products believes that solvent-based plate processing has key advantages. In terms of eco-balance and cost efficiency, it is ahead of the field and additionally offers the opportunity of determined process optimization, allowing to further improve the environmental impact.

In the case of manufacturing photopolymer flexographic printing forms, the solvent washout process has established itself as a reliable production standard due to its productivity, simple handling and efficient cost structure. If an effective contribution is to be made towards improving the environmental impact on a global level, the long-term optimization of solvent-based plate processing needs to be the main focus.  

Expanding on existing advantages
Washout of flexographic printing forms with solvents has a number of key advantages, such as:
-    Employees are familiar with the technology and processes.
-    Existing equipment can continue to be used.
-    Users can rely on a wide product range from various suppliers.
-    The available technology is suitable for all flexographic printing applications.
-    The entire range of formats is covered by various manufacturers offering systems up to a maximum format of 52 x 80 in.
-    All plate thicknesses from .030 in. to .250 in. can be processed with the solvent-based method.
-    In comparison with the standard platemaking of processing several plates in parallel, the solvent-based method provides a high level of productivity and at the same time is particularly cost-effective.
-    As a high proportion of the solvent is recycled, the environmental impact is also very low.

In addition to these fundamental benefits, the solvent technology has substantial potential to further improve the environmental impact of the process.

Five steps to improve the Carbon Footprint
According to Flint Group Flexographic Products, there are five highly efficient options for plate processing that contribute significantly to environmental protection with concrete measures.
1. As plate material has the greatest influence in terms of GWP (Global Warming Potential, see Info box), the usage of plates that are as thin as possible is recommended. In this way, the switch from plates, for example, with a thickness of .067 in. to .045 in. plates, lowers the GWP contribution by 17 %. The benefits here are not just felt by the environment, but users can also make production cost savings of up to 30%.

2. Solvent recycling plays a significant role. If the maximum recycling rate of 90 to 95% can not be achieved with the company's own resources, it may be worthwhile to use external recycling capacities.

3. In this context, it is also important to select an environmentally-friendly washout solvent. nylosolv A has been regarded as a suitable solvent in the industry for several years.

4. The use of efficient processing and drying equipment offers considerable potential for optimization. According to Flint Group Flexographic Products, the systems in the nyloflex series are particularly advantageous when it comes to energy and solvent consumption.

5. Last but not least, particularly for complex process systems like packaging production, the entire process, e.g. flexographic printing, should be evaluated to define further opportunities for improvements. Potential obviously exists, starting with substrates or printing inks right through to the service life of consumables such as sleeves, etc.

The balance of economy and ecology
The practical use of the solvent technology has been driven by continuous developments over the decades. Decisive progress could be made with the chemical composition of washout solvents, the solvent recycling and the washout equipment technology. To a great extent, Flint Group Flexographic Products did contribute to these key developments. Already twenty years ago, the company launched "nylosolv", the first chlorine-free washout solvent available on the commercial market. With the nyloflex Flowline Washer, the company developed a fully automated system to washout flexographic printing plates in a continuous inline process. Flint Group Flexographic Products also facilitates the installation of efficient solvent distillation systems through special financing options.

Key environmental aspects are usually considered for product innovations and developments and are generally seen in relation to the cost-benefit ratio. This is also stated in the Eco-Efficiency Analysis (EEA), which Flint Group Flexographic Products published in mid 2008. This comprehensive study focused on a comparison between the proven technology of the solvent-based washout of photopolymer plates and the thermal technology offered by DuPont. The data shows that the solvent technology – which makes up 95% of the global market – has a cost benefit of 10% or more, while CO2 emissions are also advantageously low.

Limited options with the thermal process
For the user it is critical that the comparison of the two processes is not limited to ecological and economical factors, but also considers further relevant aspects. For example, in the thermal method, the selection is limited to one individual supplier and a maximum of two format categories (42 x 60 in. and 36 x 47 in.). The same applies to the plate thickness, which is limited for the thermal processing to a thickness between .045 in. and .112 in. As a result, market segments such as corrugated post print can only be sufficiently operated with traditional manufacturing methods. In addition, the limited format selection has a negative impact on the quantity of waste produced during plate making. The maximum format of the processor cannot be fully utilized for each job; nevertheless, the entire web width is completely consumed.

Particularly for applications with stringent quality standards, the thermal technology may show additional problems. In the case of plates with a thickness of .045 in., which are virtually regarded as standard in the high-quality flexographic printing sector, there is an increased risk of dimensional transformation, as the high process temperatures affect the stability of the carrier foil. In contrast to this, the solvent-based technology shows no sign of limitations. Even for conventional plates, as well as for the entire range of plate thicknesses, stringent quality standards can be achieved with a high level of reliability.

Recycling – a key factor for eco-efficiency
In traditional processing of flexo printing plates, solvent recycling is a matter-of-course for users, even if only from an economical perspective. An average of 87.5 % of the solvent is recycled. If the solvent is distilled by external specialized companies, a recycling rate of 95% is achieved as standard. This value can also be achieved by large trade houses, which tend to operate modern distillation systems in-house.

Without solvent recycling, the environmental impact of plate production would be quite high. Due to the substantial solvent recycling rate, the traditional processing method is the better option in principal, when compared with the thermal technology (see Figure 1). This is valid even when the widely used polyamide web material is not used, and a new polyester web is applied to the thermal processor. This new web generation has been launched with the aim of lowering the high CO2-equivalent contribution of the polyamide web.

Simple actions points with high-impact to the environment
If the flexographic industry wants to achieve a reduction in CO2 emissions for plate processing as mentioned at the beginning, the optimization of existing processes will play a significant role. There is great potential to make noticeable improvements to the environmental balance with simple measures. In contrast, the conversion to a new technology, such as thermal plate processing, can only prove ecologically advantageous under highly specific conditions. All in all, users are faring well with their traditional platemaking process as all available formats and plate thicknesses can be used for solvent washout of flexographic printing plates; furthermore, the solvent technology is suitable for all areas of application. This is not only highly advantageous in terms of ecology and quality but is also significantly cost-effective.