Milan’s ITMA textile show brought the latest in ink technology to the fore, with fade-resistant pigmented inks on center stage.
By Vince Cahill
ITMA is the major international exhibition of the textile industry’s equipment, tools, and materials, and while it’s held just once every four years, its technologies are rapidly easing into both screen and digital printing markets. Held last November in Milan – the urban powerhouse of fashion and fabric – ITMA featured a global span of manufacturers and suppliers displaying the full range of textile machinery, innovations, and software. The show’s breadth spanned designing, resource planning, spinning, weaving, knitting, embroidery, felting, recycling, printing, washing, steaming, dyeing, drying, cutting, finishing, workflow, and even transportation: In other words, an eyeful of textile technology. A range of single-pass technologies wowed the digital market, while cutting-edge advances in pigmented inks will impact both screen and digital printing segments in the months and years to come.
Inkjet Inks Versus Analog
Inkjet technology can print many of the same types of ink and fluid as conventional analog processes, but typically at significantly lower fluid viscosities and requiring much finer particulates for its pigmented inks. Both analog and digital fiber-reactive dyes decorate cellulosic fiber fabrics such as cotton, linen, and viscose rayon. They can also color protein fibers, including silk and wool.
How does this process work? First, remember that reactive dyes form very strong covalent chemical bonds with fibers. On the other hand, printers will often use acid dye inks to decorate protein fiber fabrics including silk, wool, and nylon. Protein fibers are more receptive to acids, and acid dyes offer the type of superior sheen on lustrous, silky fabrics that demanding customers require.
If you’re printing on synthetic media, direct-print disperse dyes and their sister sublimation transfer dyes offer an effective way to decorate polyester and some other man-made fibers. Polyester fibers, in particular, are receptive to disperse and sublimation dye penetration with the addition of heat and, for sublimation dye, pressure. Dyers and decorators of acrylic fabrics will use either disperse or cationic dyes. The strength of dye bonding methods varies according to the strength of these bonds between various inks and fabrics. Sublimation transfers and direct inkjet printing of polyester fabrics yield prints that pop and wash well, which is one reason for the slow adoption of non-polyester fabric media among inkjet users.
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