Digital textile printing may be a solution for sustainability, says Dr John Provost.
The ITMA Milan in November 2015 had, as its main theme, sustainability in the textile industry (1, 2). As textile screen printing is one of the major users of energy, greenhouse emissions (kilos of CO2 Equivalent) and water usage, for cloth preparation, colour-paste preparation, screen and blanket washing and (for dye-based textile prints) in the washing-off stages of unfixed dye – the benefits of digital textile printing over traditional screen printing were very much highlighted both by exhibitors and by the ITMA organisers..
The majority of the digital textile exhibitors at ITMA, both the digital textile printing machinery suppliers (for example, 3, 4) and the major digital disperse-dye sublimation and textile pigment ink suppliers (for example, 5, 6), highlighted the savings that can be achieved in reductions in water usage, effluent and emissions savings. These savings were for so-called “dry” digital textile printing-ink technologies, which do not require subsequent wash-off after fixation, such as disperse dye-sublimation inks and textile digital pigment inks, targeting the home-textile print sector.
The textile printing industry is one of the largest consumers of water in the textile industry and there is increasing legislation to reduce pollution, greenhouse gases and water usage in the major textile printing countries, for example, India and China - the world’s largest textile screen printing market, which recently began formally implementing an updated Environmental Protection Code on January 1, 2015. The adoption of digital textile printing is seen by many traditional textile printing countries as a real answer to many of their environmental issues, which are now being addressed by enforcement of local legislation.
Digital textile print production reached over 1.2 billion square metres in 2015 (in the region of 3.6 per cent market penetration) and, with current growth rates of the order of 20 per cent/year, we should achieve 6.25 per cent market penetration of the traditional screen printing market by 2019.
Estimates for total Indian digital textile printing are in the region of 85 million square metres, approximately 7 per cent of current the digital market, still very small, considering India is the 2nd largest textile printing market, which currently prints 17.5 per cent of the global 31 billion square metres of the traditional textile prints.
The real unknown factor, which could significantly increase digital-textile print production penetration, is the possible future market penetration of the fixed-print-head-array digital textile machines (so-called ‘single-pass’ types), which have the capability to match the millions of square metres printed per year by rotary screen machines. At ITMA 2015, the MS LaRio (Dover Group), which has been available for a number of years, with a recent first purchase in India by Shrijee Lifestyle PVT Ltd of Mumbai; was joined by Konica Minolta’s Nassenger SP1, SPG Prints’ “Pike” and the Honghua (Atexco) “Vega 1” in the high-production, fixed print head array printers, single-pass market segment. (Figure 1).
Figure 2 gives the results of a study by WTiN of the UK of the current global digital textile printing market, with a market forecast to 2019.
If we speculate that total sales of high-production fixed-print-head-array (‘single-pass’) machines could reach 100 global placements in three years, and assuming production per machine of around 10 million square metres per year, we could possibly add another one billion square metres to digital-textile production shown in Figure 2, which would take digital textile market penetration to the 10 per cent digital-textile penetration of the traditional analogue textile printing market.
How to increase global market penetration of digital textile printing?
The economics of digital textile printing (cost per square metre) in comparison to traditional screen printing are always the primary factor in the purchasing decision, and this normally entails very detailed studies. These are generally carried out by means of a detailed spreadsheet analysis, using real market and factory costs in ‘like-for-like’ production scenarios (for example, similar designs, quality of final print, fabric types, same dye/pigment ink types, similar run lengths, etc.). A typical result in schematic form is shown in Figure 2, with a summary of the major data inputs required to achieve the cost comparison and a graphical result, indicating the price per square metre cross-over price for digital to analogue.
The cross-over point in Figure 2 indicates when digital and traditional screen printing are equal in overall costs per square metre of textile print production. The actual ‘cross over-point’ will obviously vary depending on the inputs used in the spreadsheet and will be different for different countries and print factories within a market. Also, the spreadsheet studies are prepared, in many cases, by the digital textile print machine manufacturer or by the digital ink manufacturer, as a ‘selling tool’ to prospective purchasers, to promote the potential of their digital-textile print machine or digital-textile ink solution.
On the digital-textile machinery side, the key inputs are the capital cost, amortisation period and interest rates, and the print production speed and daily production in square metres. On the digital-textile ink side, the cost per litre is always a well discussed area, together with the print-head operability performance, colour fastness, handle and colour strength produced on the textile fabric (ie. the amount of dye or pigment in the ink).
The impact of savings in environmental costs by water reduction, energy reduction, greenhouse emissions (kilos of CO2 Equivalent) are, in many cases, not included in these studies, but considered more of a bonus to the actual purchasing decision.
Environmental aspects of digital printing
The standard method of assessing the overall quantitative environmental impact on any product is by carrying out a total Life Cycle Analysis (7), which is a method to assess environmental impacts at all stages of a product’s life, from cradle to grave .This is very complex analysis and there has only been one detailed study reported in the public domain, by M. Kujanpaa and M. Nors of the VTT Technical Research Centex of Finland (8), which carried out a complete LCA (Life Cycle Analysis) on a digital-textile printing application using textile reactive inks and compared it with traditional screenprinting from cradle to gate, ie. when the finished textile print leaves the factory. The only other published report was an earlier Italian study, funded by the European Union (9) which was confined to savings in very low-production digital textile machines in the Como area of Italy.
The Finnish study, published in 2014, is the most comprehensive in the public domain and gives considerable detail, showing the complexity of the input data required to obtain results that can be used in detailed cost-comparison spreadsheets. This study included cotton-production environmental data and, as expected, the major usage of water in an overall LCA study is in the cultivation of the cotton. However the report does detail the most relevant information for purchasing decision-makers in the textile printing arena: ie. The gate to gate area, where (in this case) woven cotton enters the factory, is printed (by either digital or screen), finished and then delivered to the garment manufacturer. The Finland report, the most comprehensive, did show a 69 per cent savings in water usage, even though the study was confined to reactive-dye textile printing, and 40 per cent lower CO2 equivalent greenhouse-gas emissions.
By incorporating results of detailed environmental studies, derived from Life Cycle Analysis, into cost comparisons shown in Figure 3, digital textile printing become even more attractive.
These environmental benefits, together with all the other advantages to the textile printer and retailer of digital textile printing – “fast fashion”, “mass customisation”, and significant savings for the retailer as a result of quick stock replenishment (10), make capital-purchase decisions about digital textile printing machines, much more than a simple cost comparison of traditional versus digital.
2. United Nations General Assembly (2005). 2005 World Summit Outcome, Resolution A/60/1, adopted by the General Assembly on 15 September 2005. Retrieved on: 28th January 2016: http://cmsdata.iucn.org/downloads/iucn_future_of_sustanability.pdf
6.http://www.esma-archive.com/downloads/day1-track2/7%20pres%20-Christophe%20Bulliard%20-Sensient%20-Industrial%20digital%20sublimation.pdf ; slide 18
8. M Kujanpaa, M Nors, “Environmental Performance of Future Digital Textile Printing “, available from http://www.vtt.fi/inf/julkaisut/muut/2014/VTT-CR-04462-14.pdf
9. TIEPRINT – “Technology Transfer of low environmental impact ink jet printing for the production of textile products” TIEPRINT LIFE99 ENV/IT/000122 European Funded Project –Italy-GianLuca Brenna http://ec.europa.eu/environment/life/project/Projects/index.cfm?fuseaction=search.dspPage&n_proj_id=1036&docType=pdf
10. J Provost, “Cost Benefits - Calculating the Advantages of Digital Textile Printing” Digital Textile Magazine, Issue 4, 2012, p9-13
Dr Provost is an independent digital textile printing consultant and technical editor of Digital Textile magazine, published by WTiN of the UK. He was 2009’s joint winner of the Henry E. Millson Award for Invention, for the development of the first commercially available digital inkjet printer for textile fabrics in 1991.awarded by the USA, AATCC (American Association of Textile Chemists and Colorists) He also worked on digital textile inks at major chemical companies , including ICI.PLC, Zeneca PLC, Avecia PLC (now Fuji Imaging Colorants Ltd)) and BASF AG Germany.