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Printing on Specialty Substrates

(April 2010) posted on Tue Mar 23, 2010

Managing variables associated with the substrates you use is critical to quality. Find out how to work with some popular, but picky, materials.

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By Gail Flower, Johnny Shell

Printers can control many variables in the printing process; however, the customer often predetermines which substrate fits the purpose. Therefore, the more you know about all types of substrates and hot markets for certain types of substrates, the more prepared you will be to print on whatever comes your way. This article discusses printing on plastic, metal, wood, and glass and offers valuable insight from printers about production considerations, growing markets for certain substrates, and disasters to avoid.

You can use a wide variety of plastics for graphics and industrial applications. Thermoset and thermoplastic substrates are commonly classified by their physical properties with several minor classifications. These two plastic types perform very differently during the printing process.

Thermoset plastics undergo chemical and physical changes when manufactured. They cure, set, or harden to the final shape and, once the chemical cross-linking occurs, cannot be remolded. Ink systems for thermoset plastics rely on mechanical adhesion to the surface whereby the ink adheres to surface fissures in the plastic. Common thermoset plastics include aminos (melamines and ureas), casein, epoxies, phenolics, polyesters (alkyds), silicones, and urethanes.

Thermoplastics can be reshaped again and again. Their shape is not fixed, as is the case with thermosets; however, repeated exposure to the high temperatures associated with reforming eventually will cause material degradation. The following represents the most popular thermoplastics and applications:

ABS (acrylonitrile butadiene styrene) ABS can be injection molded, extruded, calendered, blow molded, and vacuum formed. ABS is used in outdoor point-of-sale signs, home appliances, plastic trash cans, and other rough-wear items. Because it has good high-impact strength, as well as heat and chemical resistance, it fits many rugged applications.

Acrylic General-purpose displays, point-of-sale and countertop signage, backlit signs and graphics, aircraft canopies, and windshields are made from acrylic. Care must be taken with solvents coming in contact with the edges of the acrylic material to avoid cracked or crazed edges. Acrylics can be heated and bent into various shapes for use in displays and brochure holders.

Polycarbonate This materials is useful for vandal-proof sheeting for signage, aircraft interior panels, safety helmets, visors, and backlit sign faces.

Polyethylene High- and low-density blow-molded containers—including high-density polyethylene (HDPE) packaging material, which allows safe handling of hazardous materials—and P.E.T. (polyethylene terephthalate) offer good barrier properties against oxygen and carbon dioxide. Polyethylene’s low surface energy necessitates pretreament or ink modification to facilitate ink adhesion.


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