The Armadillo of Package Printing

Synthetic labeling materials are grabbing the attention of converters with their durability and versatility.

WITH ITS UNIQUE shell, the nine-banded armadillo is the only mammal in the animal kingdom with armor. Made from plates of bones, its armored shell is coated with a layer of horny skin, protecting the creature from most impending harm. Even with the armored shell, this seemingly awkward animal is very versatile, able to run and even swim.

Within the package-printing industry, there is a similar anomaly. Like the armadillo, synthetic labeling materials provide durability and protection for tough applications, along with added versatility.

Synthetics

Converters are increasingly looking to synthetic labeling material to meet the needs of their customers. Yet when it comes to choosing one, knowing what constitutes a "synthetic material" is a good place to begin.

"In the '90s, things changed in the synthetic industry, moving from a niche toward a commodity market. Packaging film manufacturers decided to become involved in the synthetic market and began to throw topcoatings onto products and call them all synthetics. So, synthetics are really anything but PET and vinyl," said David Hoag, national converting sales manager for Arjobex (Charlotte, N.C.). "True synthetics are mostly all polypropylenes (PP) and polyethylenes (PE). PP and PE are the two resins that categorize 95 percent of synthetic materials."

While carrying the title "durable like film, printable like paper," synthetic materials with these two base resins have varying characteristics. Brian Verkuilen, sales representative, Contract Converting LLC (Greenville, Wis.), said, "The basic differences of [PEs] and [PPs] are in the melt index, tensile strength, and cold temperature performance." Verkuilen explained that PE will begin melting at 210°F, has low tensile but high tear-resistance, and maintains its cold strength down to -65°F. PP has a melt index of 230°F, has high tensile but low tear-resistance, and becomes brittle in freezing temperatures. Depending on the end-use application requirements, both PP and PE are good choices for converters and end users.

D is for durability

Synthetic material, by nature, is water and grease-resistant. Christopher Paskey, sales and marketing manager for Valeron Strength Film (Houston, Texas), commented, "Synthetic papers are all highly resistant to water, whereas traditional papers, unless latex saturated or coated, are not. Water resistance is key to durability, as synthetic papers will typically not breakdown when exposed to water and/or harsh environmental conditions, though not all synthetics are UV-resistant."

Kari Virtanen, business development manager, films, Raflatac ( Fletcher, N.C.), expanded on this quality. "It is the nature of the polymer. It is water resistant. … Paper is not water resistant, and that is why it is not durable."

Water and grease resistance, though, is just one factor impacting the durability of synthetic material. "The second biggest factor is the technology used to process the resin," said Steve Nimz, president of Protect-All Print Media (Darien, Wis.). "There are four basic technologies being used around the world to manufacture synthetic papers. These include mono and multi-layer blown extrusion and mono and multi-layer cast extrusion. From here, there are a variety of additional processes such as bi-axial orientation, calendering, extraction, cross lamination and an assortment of post-extrusion coatings." The many processing methods are one of the reasons for such a variety of synthetic material throughout the industry.

Beyond water and grease-resistance and the processing of the resin, UV stability may also need to be added in order for synthetic material to withstand the harsh effects of the sun. Ken Machlica, product manager, Rapid Roll at Avery Dennison Fasson Roll North America (Painesville, Ohio), said, "Typically, synthetic materials are engineered with specific 'durability' characteristics, depending upon what the intended end-use application is. Durability to some material buyers may involve UV stability for long-term outdoor applications, while others may think of durability as strength or chemical resistance."

So, where does UV stability come from? "The UV durability comes from UV stabilizers added to the resin," explained Hoag. "PEs are more UV resistant in their natural state than PPs. So, PPs must have more UV stabilizers added to the resins than PEs, and these are expensive."

Printability

While UV stabilizers make the synthetic material more durable, a topcoating or additive is provided to make the material printable—like paper. "A variety of additives or topcoatings enhance the printability, opacity, durability, and resistance properties of the synthetic paper," said John Giblin, marketing director, Granwell Products (West Caldwell, N.J.). "By varying the type of plastic material used, the processing conditions, or the additives or topcoatings used, the durability characteristics of synthetic papers can be readily modified to produce a sheet to match the desired properties of the end-use application."

The ability to be modified also makes synthetic material very appealing. There are several types of these treatment options for synthetics. "A clay coating or corona treatment is generally added to the synthetic material. Think of it as a drop of water on a waxed car—it beads up. This is what happens to ink on a non-treated plastic or film. It would bead up," Hoag explained. By adding a topcoating or additive, the synthetic material becomes printable. Solvent coatings are also used for this purpose.

Presses and inks

Another reason why converters often look to synthetic material is for its versatility on press. "Synthetic material can be used on just about every type of press, except those that generate high heat," said Paul Mitcham, national marketing manager of Yupo Corpora-tion America (Chesapeake, Va.).

Nimz added that "the resin and choice of additives have a big influence on the printability. And not unlike the durability issue, the processing technology also has a strong influence as well on how well a given product or brand prints."

When manufacturers are asked what type of inks can be used with synthetic material, their answers are the same. "Oxydizing inks," says Ted Lin, marketing manager of HOP Industries (Garfield, N.J.). "Major ink suppliers usually are able to recommend their best inks to print on synthetic material."

In addition to oxydizing inks, inks specially formulated for synthetic material can provide the best results for a synthetic material printing job. Hoag explained, "These dry by a combination of absorption and evaporation. Paper inks primarily absorb." Hoag warned converters to be careful when choosing to use a paper ink with synthetic material, as they will take longer to dry. He said, "Oxydizing inks dry down harder, which make them more durable. They make things easier and printer-friendly."

Versatility

While the armadillo may have great protective armor, this would not be very beneficial unless the armadillo was able to move around in it. In a similar manner, synthetic material is only beneficial to converters and end users if it can meet their various needs. And this it does.

"Synthetic material can really be used for anything. We have a saying here, 'one name, millions of applications,' and it's true," commented Hoag. Synthetic material is very versatile, and this makes it very appealing.

It is creating headways in numerous applications, from shrink sleeves to in-mold labels. Giblin said, "The tag and label industry is a major growth segment for synthetic papers. These include cut-and-stack, wraparound, in-mold labels, and pressure-sensitive products." One key application area that is increasingly using synthetic material is shrink sleeves.

"The synthetic application that is turning the world upside down," according to Lori Davis, executive VP, Contract Converting LLC, "is shrink sleeves—primarily because bottles are getting turned upside down with the creative graphics available to shrink-sleeve applications." These labels are shrunk over containers, particularly uniquely-shaped bottles, and may "serve as the tamper-evident label as well as the primary label, all in one," said Davis. Synthetic materials are enabling converters to create labels that are multifunctional, meeting end-user needs through their durability and versatility.

Nimz said, "Concern over safety and product liability is another reason some companies opt for synthetics. In this case, marketers are looking for a tag, label, placard, or sign that is going to remain with the product for its useful life or until intentionally removed by the end user."

Rich Witmer, marketing communications manager, Valeron Strength Films, foresees RFID technology expanding with synthetic material as well. "RFID seems to be everywhere at the moment. The ability to embed or print radio antennae on substrate material is obviously of great interest to the RFID users and manufacturers. Synthetics offer greater durability than traditional paper labels and therefore greater protection of the RFID technology. Coupled with the fact that the cost per unit of RFID is still high, we believe RFID will grow on synthetic labels, before moving to paper."

Get 'in' with it

In-mold labeling, though, is one application that is greatly benefitting from the characteristics of synthetic material. "It is used extensively for the in-mold market," said Hoag. He points to bottles such as Ajax, Tide, and Minute Maid as prime examples of this application.

"Converters are moving away from paper labels, and they are using synthetic labels, which are more efficient and compatible with the bottle," Mitcham said, confirming the trend. In-mold labels are applied when the heat from forming a bottle activates an adhesive on the back of the label and seals it to the bottle. The durability of synthetic materials makes it a prime substrate for converters to offer their customers.

Phil Courtier, director of product leadership at Multi Color Corp. (Cincinnati, Ohio), said, "Typically, companies like Proctor & Gamble will come to us with a need. For instance, if a juice company is looking for a container that will withstand a particular environment during the filling and production of the product, and then withstand refrigeration or a moist environment, we will recommend synthetic materials for that need."

And synthetic labeling material has made the process of in-mold labeling much easier. "The biggest advantage in in-mold labeling is the use of synthetic materials and not a paper base. Synthetic materials are much more user friendly for blow molders," Courtier said. "The paper materials must also be removed for recycling; but as synthetic materials have a similar makeup as the plastic bottles, they can be melted together during the recycling." These benefits, along with its ability to withstand harsh environmental conditions make synthetic material increasingly popular.

Though the armadillo may not be the most well-known creature in the animal kingdom, it is known for its protection among its counterparts. Similarly, synthetic material is becoming more known throughout the packaging industry, offering converters and their customers the reliability, durability, and versatility they need.

Giblin confirmed, "Tag and label converters can now use synthetic papers to design better products, more durable and more versatile for their customers. In this respect, the versatility and strength characteristics of synthetic papers will not only increase added value, but will also increase product safety." From its versatility in applications to its durable nature, the characteristics of synthetic material make it one substrate that has endless potential.

by Joy English, Assistant Editor