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Inkjet Printing-A Revolutionary Ecofriendly Technique for Textile Printing

Inkjet Printing-A Revolutionary Ecofriendly Technique for Textile Printing

Indian Journal of Fibre & Research Vol. 26. March-June 2001. pp. 156-161

Inkjet printing-A revolutionary ecofriendly technique for

Sanjay Gupta" National In stitute of Fash ion . Hauz Khas, Ne w Dcl hi 110016, India

Some of thc aspects of inkjct or di gital printing, such as com pari son bctwecn conventional and di gita l printing. di git al printing systcms, suitablc inks bascd on and pi gments, colour man agc ment software, application and iuture scope of digit al printing, arc brieny discussed in view of the demand-activated manufac turing architect to satisfy th e chan gin g fa shi on trends and new market requ irements.

Keywords: Inkjet printing, Rotary scrcen printing, Textile printing

1 Introduction has been pushing the print production towards th e In ITMA 1999, an array of diffe rent developing countries. As a result, Far East has the fo r di gital printing on fabric was presented. Though major share of 50% with the USA hav ing only II % the idea had been around for nearly IS years, it was and the EU, 15 %. A major reason for thi s shift is th e not until now th at equipment adequate enough for long, polluting and capital intensive nature of production on tex til es was show n. However, th e conventional tex tile printin g. Di gital printing has the 'different competing technologies th at were di splayed potential to reverse this trend. showed a lack of clear-cut direction and served onl y Changing fas hion trend s an d new market to confuse buyers, most of wh om were un exposed and requirements are also pushing th e dri ve for digital un ed ucated about the capabilities of these printing. The most influencing factors are: technologies. Educated buyers were wary of purchasin g a technology th at might be obsol ete by th e • Personalization and quick response: rapid end of the year. However, as we moved through th e change necessitates quicker transposition from year 2000 into 200 I, th e developmen t of bigger, faster des ign to production and shorter print run s as a and better print engines capable of increasing print consequence. speeds is being reported. The commercial availability • Design piracy: original designs are copied very of this technology will redefine th e way the traditional fast and repeat orders are rare. Speed in tex tile producers run their business . The importance transposition and quick potenti al profit rea li zation of understanding the process and building ex peri ence are important. with the current technology cannot be underestimated. • Printing on new and unusua l surfaces: printed Thi s briefly di sc usses some of the aspects of made-up products, engineered prints, and digital or inkjet printing, such as comparison between technical tex tiles are demanded by customers. co nventional and di gital printing, di gital printing • Environmental constraints: environment-friendly systems, suitable inks bases on dyes and pig ments, wear properti es and production processes. co lour management software, application and future • Press ure on costs: short fabric len gths mean scope of di gital printing. shorter inventories and sav ing in storage space.

2 Trends Influencing the Emergence of Digital 3 Conventional vs Digital Printing-t,S Printing)-] If one consi ders conventional textile printing, It IS Worldover, 11-1 3% of th e tex til es produced are immediately obvious th at the variabl e with the printed. Thi s amou nts to nearly 27 billion running greatest effect is fabric length . For long lengths, meters of tex ti Ie material. Dynami cs of global trade analog printing technology like rotary prin ting is fast (30m/min on an average), continuous and economical. "Phonc: 6850455; Fax : 009 1-0 11 -685 11 98: The colour ga mut is wide and no special pretreatment E- mail : sg upt a34@ hotmail.com of fabric is required before printing. GUPTA: INKJ ET PRINTING 157

For short runs, however, the process is colourways can be printed. Invento ry and polluti on uneconomical owing to hi gh downtime, hi gh wastage control costs are minimal as all the goes onto the of fab ri c and inks, hi gh cost, high labour fab ric, no thickener or paste is used and, water and cost and cost of time spent on colour-matching, paste energy consumptions are low. The technology is making, sa mpling, design, registration, etc. amply suitable for just-in-time del iveries and mass Operations like screen engraving, print washing, and customization. sc reen washin g add signi ficantly to the pollution load. The technology is, however, still limited by low Des ign sampling or proofing is particularl y a very production speed, low avail abi lity of fast and low­ lengthy and expensive process (Fig. 1). viscosity dyes, and small size of colour cartridges. Di gital pnntIng, therefore, offers di stinct Fabric mu st be speciall y prepared to be abl e to run on advantages for short runs, sampling and proofing. these printers in open width condition and absorb There are no screens; consequently, all costs dyes quickly. Many , like pearl, metallic and pertaining to screen engravi ng, paste mak ing, strike­ white, are not yet avail able for printing through these offs, downtime and wastage are eliminated. There are printers yet. Material handling is also limited . Stretch no registration probl ems and unlimited choice in knits and performance fabrics are not printable as yet. terms of repeat size is available. Any number of Durable solutions for post printing operations like print fixation and are yet to emerge.

Analog Printing 1 3 4 Digital Printing Systems . ,4.6 A di gital printing system for applicati on on is an integration of four components, namely the inkjet head, ink chemistry, medi a and the colour management software. For each component, various technologies and suppliers exist. Based on th e choice Production of Artwork T of level of technology ava il able today, two major types of system, namely the Drop-on-Demand (DOD) Traditional! Digital 1 Week Methods and the Continuous Ink Jet (CIJ), have emerged (Fig. 2). The most important features of the inkjet printer are the printing head and the nozzles. In case

1 Inkjet Printing i Engrave Designs 6-8 Weeks

Color Matching PrmilJr.tion of Artwork - Digital Files T 1 Week - Design Manipulati

2 Weeks

1 Hours . ~

Fi g. I-Conve nt ional vs digital printing 15 8 INDIAN J. FIBRE TEXT. RES ., MARCH-JUNE 2001

Ink Jet Technologies

I I I Continuous Ink Jet (CIJ) Drop-on-Demand (DOD)

I I r-' I I Multi- Binary Piezo Thermal l)eflection Deflection I J j Jemtex Scitex -Epson HP, Canon Linx Stork Brother Xerox Image Domino Tektronix Lexmark Taxat Toxot Aprion Videajet Spectra Willet Xaar Konika Trident Seiren

Fi g. 2- lnkjet technologies in textile printing of both these technologies, numerous nozzles are used crystals can use any type of dye or and are for each colour. These nozzles are 10-100 J.l in more suitable for hi gh volume printing. diameter, providing a resolution of up to 720 dpi (dots Continuous inkjet, on the other hand, generates per inch). Between one thousand and one million ink droplets continuously, but only the required droplets droplets are processed per second. are directed towards the target spot of the fabric by Many digital printing solutions have been made electric charge and deflection. Unneeded droplets are possible through integrat ion of the experien ce of redirected to a gutter. C[J printers are further different companies, speciali zing in their respective classified into two types: binary and multi-deflection. fie ld s. One such group is Ciba Speciality Chemicals, The binary systems are expensive and not adapted to Sophis and Mimaki. Another is Ciba Spec iality process colours. Multi-deflection systems are cheaper, Chemicals and Di gital Printing Systems (A prion). A allow for larger drop size and multiple dye types. third group ha vin g dye heads Zimmer (Austri a) and They are, therefore, sui ted for textile printing at Jemco (Israel) and ink head DyStar is developing a high speed. new printer which is claimed to be ab le to ac hieve production speeds of 200 m/h. This printer named 4.2 Ink Chcmistry and Mcdia7 "Cromotex" is being designed for fabric widths of 2 m Inks for digital printing require special control on and printing eight pre-mixed colours with a resol uti on parameters like viscosity, conductiv ity, surface of 100 and 125 dpi. tension, chemical stability, physical stability, pH and foam-free properti es. Without the colour chem istry 4.1 Inkjct Hcads In DOD system, the drops are generated and base and in-formulation technology, th e particle size ejected when required. Drops can be generated either distribution required for such inks is not poss ibl e. A by a bubble (thermal) jet or a piezo crystal. These further requirement is ideal combination of ink and print heads are relatively simple and cheap; however, substrate. their life and applications are limited. Only very small BASF and Ciba Specialty Chemicals (Table 1) are droplets are generated. Consequently, a very large the two major manufactures of reactive inks for number of nozz les are required to get acceptable and cotton blends, em ul sion inks for PET, acid inks results. Thermal jets are inexpensive, use water- based for , polyamide and woo l, and pigments for all inks and produce a very fine droplet size. Pi ezo types of fibres . GUPTA: INKJET PRINTING 159

Table I-Inks for various substrates2 Substrate BASF AG Ciba speciality chemicals

Cotton and Reactive: Procion Reactive : Cibacron MI cotton blends Pigment: Helizarin Pigment: Irgaphor TBI ( suitable for all textile subtrates) (suitable for all textile subtrates)

Wool Reacti ve: Procion Acid: Lanaset SI

Silk Reactive: Procion Acid: Lanaset SI

Polyamide Acid: Lanaset SI

Polyester Emulsion: Bafixan Emulsion: Terasil DI Emul sion: Terasil TI ( transfer print)

Another choice for the manufacturers of inkjet generated on the fabric by mixing and exactly placing products is to use dye- or pigment-based inks. multiple single drops. When printing on paper, just According to most experts, this choice four basic colours (cyan, magenta, yellow and black) should depend on the desired application. Dye-based are used, while for printing on textiles, usually 4-12 inkjet inks use a liquid colourant, that is usually colours are used. Eye blends the individual colours to water-based, to turn the media in specific colour. create the required colour shade. Theoretically, an Because of their makeup, dye-based inks are not unlimited number of shades are available. Spot waterproof and tend to be affected by UV light. This colours, on the other hand, are premixed dyes (as used results in the colour changing over time. For optimum for screen printing) giving exact shade reproduction, performance, this type of ink also requires a proper increased coverage and thereby hi gher productivit/. media, selected according to the appli cation. If the media is too dense, the ink can't penetrate and beads 4.3 Colour Management Software on the surface. If the media is too absorbent, the dot Digital printing software controls design, colour gain is too hi gh. cal ibration, colouration, colour resolution, inkjet Pigmented inks use a solid colourant to achieve printer control. colour. The line quality and accuracy of plots The design, scanned or produced with creative produced by pigment-based inks are usually superior software, is translated into a hi gh-resolution image to that of dye-based inks. With this process, the solid fi le. Interactive functions, such as the repeating of the particles adhere to the surface of the substrate. Once pattern, retouching or processing of half tones, the water in the solution has evaporated, the particles cleaning-up and defining of the contours, are the basic will not go back into the solution, and are, therefore, requirements. Ordinary design software packages, waterproof. In addition, the pigmented inks are much already widely used, such as Photoshop, Painter, more UV- resistant than dye-based inks, and hence it Freehand, etc. offer good value. A design created in takes much longer for noticeable fading to occur. this way is already based on digital data and can, Another advantage of this ink is that the choice of therefore, be further processed without loss in quality media is much less important. and in the shortest possible time. The simulation of print samples by inkjet printer Given these facts, it would seem that the future of should replace the sample table. The use of multiple the inkjet industry lies solely with pigmented inks. colours, which is synonymous with textile printing, This, however, is not the case as inkjet manufacturers can be achieved now-a-days with the printers that use foresee continuing production of both pigmented and up to 16 different colours. This enables colourations dye-based inks. One reason for this outlook is that made up with colour mixtures and spot colours. presently dyes are much more suited to everyday Calibration of the inkjet printer is indispensable and applications, run cleaner, provide better yield, offer the on ly way to achi eve a true translation from better particle size and are easier to filter. computer screen to print result. In ks are used by the printer in two ways- process Those companies, which have already experi­ colours and spot colours. Process colours are mented with digital proofing, have experienced the 160 INDIAN J. FIBRE TEXT. RES., MARCH-JUNE 2001 potential cost savings possible with this method. By As presented at ITMA, the cooperation between an estimate, approx. 6% can be saved in screen Stork (Netherlands) and Lectra Systems () is production, and as much as 20% in sampling by moving in the same direction. According to the digital proofing. The labour cost of conventional agreement, Lectra Systems will develop a complete sampling is also higher than that of the production of range of digital printing systems combined with CAD printing screens. and automated cutting systems. The Manage Textile Print system (MTP) by Stork will integrate the 4.4 Process complete textile printing process. It will enable colour The knowledge of the processing chain is the matching between design and all textile-printing printers' most valuable know-how. Pre- and post­ systems offered by Stork, including all Stork rotary treatments of the printed fabric enable fashionable screen-printing machines. effects and add value to the textiles. The cooperation Other areas of application include the printing of among printer producers, (inks) and curtains, decorative and furniture fabrics, home finishing companies (pre-and post-treatment) results textiles, roller blinds, table and bed , wall paper, in complete package. , woven ribbons and labels, banners and flags, ties and scarves, etc. The customers, who discovered If pre- and post-treatments are carried out by third this service as an inexpensive way to produce small parties, a problem of logistics arises. In view of this, high-quality collections, are from the entire home and the textile machine producers have come up with a domestic textile sector, interior designers and new solution for those companies that do not have architects, decorators, tailors and textile, bed and sufficient facilities for pre-and post- treatments of the furniture traders. fabric. Printing systems with integrated pre-and post­ treatments are now made available, for instance by Arioli (Italy). 6 Muitiprint Concept - A Case Studl The multiprint concept envisages a textile printing S facility where many production machine units would 5 Applications of Digital Jet Printing ,8,9 be placed in one room analogous to in a Sampling or proofing is the most obvious use for weaving . With an investment of, for instance, digital jet printing as its conventional cost in the US$ 6000/unit and printing speed of 6m1h (ISO cm is extremely high and producers are fabric width), such a textile printing room with 50 under constant time pressure. units and two shifts could produce more than 2000 In Western Europe, the production of printing mlday. Such a textile printing concept for high quality screens costs about US$ 400 per colour. Proofing, textile prints, with above capacity and investment, from the conception to printing on fabric, takes a would actually be feasible with today's technology minimum of 4-6 weeks. If 20 designs/collections with with the usual advantages and limitations. an average of 8 colours are taken as an example for calculation, the production of printing screens alone The textile finishing (, printing, finishing would cost more than US$ 60,000. To produce such a and converting) company Seiren Co. Ltd., Japan, has number of collections, 10 - 12 weeks of development successfully used inkjet technology in production for time is needed. Inkjet printing can thus offer a several years now. The Yiscotecs system is the first cheaper and much quicker sampling route. commercially successful digital inkjet printing system in Japan. Research and development started 10 years In , the digital production is already ago and consumed about 20 billion JPY. Since then, standard from the draft design to the 200 staff have produced approx. 10 million m2 and all the way to the making-up process. For this annually at a value of 13 billion JPY. The application purpose, Shima Seiki (Japan) offers Systems Apparel areas of the products are: car upholstery fabrics Design, ATD. This system includes modules for (40%), swim wears (18%), ladies outer garments planning (draft design, printing, weaving and knitting) (10%), leisure wears (10%), sports wear (12%), and and making-up (sample production, graduation, miscellaneous (10%). marking, cutting and knitting). The company now also offers a module for printing as well as a printer SIP The miscellaneous include large- surface products 120. The system is complemented by a module for such as flags, posters or billboard surfaces. Almost all "presale sales promotion". the textile substrates (like cotton, PET, polyamide, GUPTA: INKJET PRINTING 161

Table 2-An estimate of growth of hardware installations of digital printers Market segment 1998 1999 2000 200 1 2002 2003

Sampling and proofing DOD, Thermal, Piezo 375 558 765 1045 1390 1962

Personalization DOD, Piezo 150 728 1500 2000 2502 3862

Customization DOD. Piezo 220 396 588 2328 3648 5700

Agile manufac turing 5 12 50 75 Massive array DOD, Piezo (speculati ve)

Short runt Rapid response 8 35 55 Massive array DOD, Piezo (speculative)

Production substitution (speculative) 100 400 600 700 800

Total 745 1782 3258 5993 8325 12454 elastane, etc.) as well as various weaves, brushed hardware installations of digital printers will grow in fabrics, artificial furs and knitted goods are used in future, keeping in mind the various market segments. printing. An estimated 1000- 1500 digital printers are in use The qualitative improvements are dramatic. In world-wide mainly in US and EU. 1990, Seiren had a fault rate of 18 %, but by 1998 it Irrespective of how promising digital printing may was a mere 1.4%. This reduction was achieved by appear, it is unlikely to replace analog printing reducing machine defects, such as clogging of nozzles methods like rotary printing, which will remain the or traditional printing with an average fault rate of 4- preferred route for large batches. Digital printing will, 5%.The foremost advantage of the Viscotecs system however, gain significance in printing small batches. is the reduction of the throughput time from about 2 The current digital printing cost is between US$ 5-10 months to less than 10 days. (ink plus substrate) per square meter. It is profitable This low-fault rate and the high efficiency, for quantities under 500 linear meters for one design. exceeding 90%, compensates for the relatively slow Small print shops and custom garment manufacturers, printing speed of the printers and justifies Seiren's serving local demands, will make use of this claim as to the profitability of this production method. technology. The non-polluting, environment-friendly Seiren also developed all the inks and chemicals. nature of technology will make the adoption easier. Considering that for years the suppliers from the Production of small batches, presently being executed Far East, especially from Japan, have operated with in low-cost countries (with high response time), will minimum quantities of several thousand meters per also shift to local markets in the developed countries. colour, Seiren's new minimum quantity of 300 m2 is An estimated 10% of the total print market will be quite revolutionary. There are 16,070 colours taken over by digital jet printing in next 10 years. available. Besides the known advantages of inkjet technology, Seiren further claims that thi s technology References requires no stock, which reduces printing costs a great I Winkelbeiner S, 1111 Text Buil, (6) ( 1998). deal. Within a period of three years, the stock-keeping 2 Bohringer A, Il1t Text Bul/, (2) (2000). costs reduced from 27% to 5%. So far, the largest area 3 Klemm M, 1111 Text BIII/. (3 ) (2000). printed has been SOx 40 metres. 4 http://www.tcchexchange.comlthel ibrary. 5 http://www.zimmer.com. S 7 The Future for Digital Jet Printing ,8,9 6 Owens P, Il1t Dyer, (2) (2000). It is hard to say what proportion of the market uses 7 Ciba Speciality Ch emicals, private communication. or will use digital technology in comparison to 8 Cohen N. www.aprion.com.private communication. conventional printing techniques. Table 2 shows how 9 Lam L, www.prima.com.hk. pri vate communication.

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