Screen Printing - February/March 2016 - (Page 26)

The Power of PigmenT Milan's itMA textile show brought the latest in ink technology to the fore, with fade-resistant pigmented inks on center stage. 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 26 screenprinting 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 nonpolyester fabric media among inkjet users. why Pick Pigmented inks? Printed and fixed dye-based inks can produce vibrant color and soft hand. Most dyes, however, are vulnerable to fading when exposed to the UV energy in sunlight and the chemical effects of ozone and oxygen. Screen-printed pigmented inks lack the soft hand of dye-based inks, and typically have a heavier hand than inkjet pigmented systems. Pigmented inks generally yield much greater resistance to fading when exposed to sunlight, oxygen, and ozone than dye-based inks. Also they do not require washing to remove excess dye after heat setting, as direct dye printing typically does. Of course, buyers of apparel fabrics generally prefer the soft hand and vibrancy of dye, even though such fabrics are prone to fading. On the other hand, buyers also prefer pigment printed fabrics when they are exposed to sunlight, as outdoor signage, curtains, some home furnishings, and even decorated T-shirts often are. Some manufacturers of inkjet inks have introduced pigmented inks with relatively soft hand while others have been developing UV-absorbing coatings to protect dye-based inks. Which type of ink should a printer chose? Suppliers typically dedicate each of their textile inkjet devices to a

Table of Contents for the Digital Edition of Screen Printing - February/March 2016

Screen Printing - February/March 2016
Contents
Editorial Insights
Pressing Issues
New Products
Are You Confused about CPSIA Regulations?
Clothing Becomes Electric
The Power of Pigment
Understanding the Garment: Selection, Testing, and Prep
Distributor/Dealer Directory
Classifieds
Ad Index
Who’s in Charge here?

Screen Printing - February/March 2016