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| Issue date:01/04/2008 |
| ATA Journal for Asia on Textile & Apparel - Apr 2008 Issue |
| Source:Journal for Asia on Textile & Apparel |
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| In recent years, the growth in digital ink jet printing has stimulated further product development in ink formulations that suit particular jetting requirements of various types of ink jet printers used worldwide, Ian Holme writes. |
Textile printing processes use a wide variety of chemical-based materials to assist textile printers in achieving fine line definition and appropriate levels of color fastness for the intended end-use.
Conventional textile printing can apply dyes that are fixed by saturated stream, superheated steam, dry heat transfer printing or by dry heat fixation. Alternatively, pigment printing uses dry heat fixation to cure the print binder. Pigment printing has grown in importance because of the ability to print all types of textile substrates and especially blends such as polyester / cotton fabrics. More recently the growth in digital ink jet printing has stimulated research and development into ink formulations that suit the particular jetting requirements of the various types of ink jet printers used worldwide.
The high-speed jetting of inks in digital ink jet printing is crucial in attaining successful printing on textile substrates. Because of this, the physico-chemical properties of the ink must be very carefully formulated for the specific print head and for the type of fabric pretreatment used. The ink formulation must achieve the delicate balance of properties that will ensure optimum ink stability during transportation, storage and use, high-speed jetting characteristics in order to achieve fault-free printing and satisfactory wetting and absorption of the ink droplets when these reach the pretreated fabric surface.
While conventional dyestuffs for textile printing may contain 30%-50% organic colorant, the dyestuffs and pigments used in ink jet printing inks must be highly purified and then milled down to a fine state of sub-division. Particle sizes are generally less than one micron and the dyestuff chromophore must be very strong because, typically, the dyestuff concentration may be about 10% of the ink formulation. The latter may be complex and in the case of water-based inks could include demineralized water, a water-soluble solvent for viscosity control, dyestuff or pigment, surfactants for wetting and penetration, buffer solution for pH control, biocide to prevent fungi and bacterial growth, as well as other additives.
Dispersion of dyes down to nano size
For digital ink jet printing using piezo printing heads, J-Teck 3 Srl (Italy) developed J-Eco Subly Nano NS-60, which is based on J-Teck 3 Nanodot Technology. This is designed to provide an optimum dispersion of disperse dyes which are reduced in size down to nanoparticles.
This innovative technology is utilized by digital ink jet printing of the design image onto coated paper and then transferring the image onto polyester fabric using a temperature of around 210. Mixed synthetic fabrics containing polyester down to 60% can also be printed using J-Teck 3 Nanodot Technology.
Applying disperse dyes in nanoparticulate form imparts significant technical advantages in terms of increased brilliancy of color, increased storage stability and fast drying onto dedicated media. J-Eco Subly Nano inks thus provide vibrant bright colors with good color fastness properties.
The inks offer optimal ink fluidity and printability through piezo heads with good release on paper and image definition after transfer. The J-Eco Subly Nano range of inks are free of alkyl phenolethoxylates, according to the EC Directive 2003 / 53 / CE.
Innovative inks for digital printing
DyStar from Germany introduced Jettex R reactive inks for digital textile printing with piezo printers. The Jettex R range is based upon standard reactive dyes used for textile printing, covering the entire color space.
Jettex R inks are classed as outstanding inks for digital printing onto cellulosics, silk and wool and are ideal for fashion fabrics for both womanswear and menswear.
A particular advantage of the Jettex R range of reactive inks is that they ensure excellent transfer of digital sampling to conventional print production, providing high reproducibility coupled with top color fastness and brilliance of color. Jettex R inks meet top runnability requirements in digital printing and are easy to wash off.
The Jettex R range of reactive inks for digital ink jet printing using piezo printers consists of nine colors that span a wide area of color space, namely Yellow 6G E-O, Blue 3R E-O, Golden Yellow R E-O, Turquoise GM E-O, Orange RN E-O, Gray GM E-O, Red FB E-O, Black BN E-O and Red 4B E-O.
DyStar's Jettex inks |
Jettex A acid inks from DyStar can be piezo-printed onto silk, polyamide and wool. Based on standard acid dyes used in textile printing the Jettex A acid ink range consists of 10 colors providing a high color yield coupled with brilliancy over a wide color gamut. Fluorescent dyes in the range can be used as bases for new coloristic ideas especially in the important area of swimwear.
DyStar's Jettex D disperse inks are designed for direct digital printing onto polyester substrates using piezo print heads. This important range of inks is considered ideal for use in end uses such as advertising, flags, banners, home textiles and fashion fabrics.
With eight disperse inks, a good coverage of the color space is achieved. The inks are carefully selected to provide the textile printer with high color yield, brightness and brilliancy of color. A major advantage of these Jettex D disperse inks is that they possess outstanding color fastness properties on polyester, which cannot be achieved using sublimation inks. As a result, Jettex D disperse inks offer high color fastness to sublimation and are suitable for end uses requiring top light and weather fastness.
In addition, Jettex D inks are based upon the standard disperse dyes used in direct printing and hence are suitable for all common methods of print fixation. Jettex D inks are classed as environmentally sound and provide excellent performance on Epson print heads.
Potentials seen in automotive fabric sector
The automotive fabric sector is an area in which enhanced coloristic opportunities may be created using high-tech digital printing inks. Huntsman Textile Effects from Switzerland produces Terasil DI-HL disperse inks, which have been formulated for the direct digital printing of polyester fabrics widely used in car seats.
The Terasil DI-HL range of eight colors can be applied to polyester fabric that has been given a special textile preparation to ensure high color yield coupled with excellent print definition. The disperse inks are designed to provide a broad spectrum of colors that provide the high color fastness to light demanded in the automotive fabric sector. Digital ink jet printing of automotive fabrics offers substantial advantages in terms of technical performance, speed, flexibility and costs.
Jettex Ultra Cleaner and Jettex Soft Cleaner from DyStar provide an efficient cleaner package for digital printing systems. Jettex Ultra Cleaner has been designed to provide highly efficient digital ink jet printer maintenance. Jettex Ultra cleaner is composed of non-corrosive ingredients, so that it is compatible with all common materials, e.g. metal, plastic and rubber. It can thus be used safely for cleaning ink feeding systems, print heads and machine parts and is very effective with water-based inks, like DyStar's
Jettex R, A and D ranges of reactive, acid and disperse inks. Jettex Soft Cleaner is a mild solution designed for maintenance and conditioning of digital printing machines used with water-based inks and is ideal for use as a storage medium if there are likely to be prolonged machine downtimes.
Conventional pigment printing using binders is now established as the major printing system because it can be applied to all types of fabrics and fiber blends. Some pigment preparations are, however, more susceptible to the atmospheric pollutants commonly experienced in Asia, especially in densely populated cities with heavy traffic loads in China and India, for instance. In this connection, DyStar has recently introduced two new blue pigment preparations, namely, Imperon Blue HF-5R and Imperon Blue HF-T. They have been chemically engineered to provide superior color fastness to oxidising gases like ozone compared with comparable pigments based upon the CI Pigment Blue 15.x types.
Inks commercialized for new digital printers
From earlier this year, DuPont Digital Printing started selling digital textile inks to OEMs, enhancing the company's position in the rapidly growing digital textile printing market.
New inks were developed to fit with new-generation digital printer (Pictured: a DuPont Artistri machine) |
DuPont digital textile ink offering includes the aqueous-based Artistri 700 series (disperse dye ink, acid dye ink, reactive dye ink and pigment ink), and Solar Brite ink sets, for medium viscosity print heads. For lower viscosity print heads the Artistri 500 series acid dye and reactive dye inks are offered.
The 700 and 500 series acid dye ink is used primarily for printing on nylon, wool, silk and nylon/Lycra blends in activewear, swimwear, intimate apparel, flags, banners and accessories including ties and scarves.
Michael Moore, DuPont Digital Printing's global business manager, industrial inks, said over 250 Artistri systems were installed globally and "we believe the digital textile market will have significant value for these ink sets." The Digital Printing business unit is part of the Imaging Technologies division of DuPont and focuses on providing digital printing solutions for various applications.
Another chemical supplier, Clariant offers products for most fields of textile printing applications on rotary and flatbed printing machines.
The Printofix pigment printing products are suitable for a variety of fibers. These water-based pigments offer good dispersion. Together with Printofix auxiliaries, the products help deliver stable printing process and good performance for end users.
Clariant provides differing products for various fibers. It suggests using monochlorotriazine dyes, such as Drimaren P dyes, to print on cellulosic fibers as the dyes gives a reproducable process and good wash fastness.
On polyamide, acid and metal-complex dyes can be good choices, including Nylosan and Lanasyn dyes, the company says. Disperse dyes can be adopted to print on polyester.
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| Copyright © Adsale Publishing Limited. Any party needs to reprint any part of the content should get the written approval from Adsale Publishing Ltd and quote the source "ATA Journal for Asia on Textile & Apparel", Adsale Textile English Website - www.AdsaleATA.com. We reserve the right to take legal action against any party who reprints any part of this article without acknowledgement. For enquiry, please contact Editorial Department. |
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| Copyright © Adsale Publishing Limited. Any party needs to reprint any part of the content should get the written approval from Adsale Publishing Ltd and quote the source "ATA Journal for Asia on Textile & Apparel", Adsale Textile English Website - www.AdsaleATA.com. We reserve the right to take legal action against any party who reprints any part of this article without acknowledgement. For enquiry, please contact Editorial Department. |
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