If you take the first part of the word “polycarbonate” and define it, you’ll find that “poly” is of Greek origin and means “many,” or “an abnormal amount.” The application of this prefix is particularly fitting for the polycarbonate used in the sign industry, considering the long list of signage applications that include the durable sheet material.
Jay Millhof, strategic account manager, image market for SABIC Polymershapes, cites examples: office park directories, mass transit signs, formed 3-D faces, backlit signs, digital advertisement screens, channel letters, menu boards, electronic messaging fascias, monument signs, pylon signs, and permanent sign boards. The list could go on, he says.
“Our customers are leaders in visual design,” Millhof says. “They look to us for the materials and value-added services that will help them bring to life a vast variety of incredible shapes and images.”
Because these materials can be cut, decorated with graphics, and custom-formed, they are a versatile option to sign makers across many fields—even when put up against similar substrates. Add in the lighting options available with polycarbonates, and its viability in both indoor and outdoor environments, and one can see the level of usefulness of these materials.
As Brenda Hogan, channel marketing specialist, Palram Americas, explains, “Polycarbonate sheets are an ideal substrate for both digital and screen printing, and it can be cold bent, fabricated or formed for a wide variety of both indoor and outdoor sign applications. With its high-impact resistance, clarity and light transmission properties, polycarbonate material is ideal for applications ranging from backlit and illuminated signage to channel letters, LED sign faces to exhibits, P.O.P. displays and merchandise racks.”
And that’s just the start of how polycarbonates can be used.
Tough and Versatile
Ken Licklider ?market development specialist at Covestro LLC (formerly Bayer MaterialScience LLC) says one of the key benefits to polycarbonates is its strength.
“Polycarbonate can be expected to last for the life of a sign,” he says. “Due to its superior impact strength, polycarbonate is a better alternative to acrylics where breakage resistance is important.”
Milllhof states that even though polycarbonate is lighter than glass, it “delivers more than 30 times the impact strength of acrylic, and 10 times that of impact-modified acrylic, so signs maintain their appearance over time, and can be used in areas of high vandalism.”
That’s an impressive quality for a substrate, ensuring users that it will withstand a number of different problematic elements. According to Hogan, because polycarbonate is rigid and “virtually unbreakable,” it offers more advantages than acrylic.
“Polycarbonate offers greater heat resistance, higher impact strength and increased resistance to breakage," Hogan says. "In fact, most polycarbonate manufacturers offer a 10-year warranty against breakage, including from hail impact. And polycarbonate is also more flame-retardant than acrylic.”
These advantages also increase the versatility of polycarbonates, known to be an outstanding material in both standard and custom sign projects.
“It’s an excellent choice for decorated outdoor signs,” Millhof continues, “including cabinet signs and channel letters. LEXAN? polycarbonate sheet comes in a variety of specialized sign grades, can be thermoformed with crisp detail, offers excellent aesthetics, and is tough enough to withstand high impact and abuse.”
Challenging Variables
But with strengths also come weaknesses, and sign makers should be aware of factors that may lead to the failure of a sign made with polycarbonates. As mentioned earlier, there are always risks with outdoor signs from vandalism, and general weathering, but Hogan warns of other potential challenges.
“There are many variables that would affect the longevity of a polycarbonate sign,” she says. “Geographic location, exposure to the elements, contact with chemicals, proper installation, the use of a UV-protective coating. Palram offers a 10-year warranty for its PALSUN UV Protected series of products, which covers light transmission, yellowing and breakage, but a polycarbonate sign can last for many, many more years.”
Added Elements
Without a little style and creativity, no sign will be set apart from others. Even with all of the fundamental qualities that polycarbonates possess, they are further benefited when combined with elements such as lighting, cutting, and printing.
Lighting—“Backlit electric signs for fast food chains, gas retailers and box stores are the most common applications,” Licklider says. “Any raised or embossed sign face is a good fit for polycarbonate. Also, polycarbonate is being increasingly chosen as a substrate for large or thermoformed channel letters and cloud signs.”
Technological improvements have actually helped push the market forward for materials like polycarbonates as they can be used in a larger variety of areas. And because polycarbonates are so durable in the first place, they’re a great option to pair with lighting elements.
“With the continued growth and ongoing development of LED lighting in the signage market, there’s been a higher demand for polycarbonate sheets due to its design flexibility, high clarity and light transmission and excellent hiding power,” says Hogan, citing Palram’s PALSUN Sign Grade (SG) polycarbonate sheets as a provider of “exceptional light diffusion while eliminating LED hot spots even in applications that require light diffusion from a much closer distance to the light source. (i.e., shallow channel letters, slimmer sign cabinets).”
Licklider sees the benefits of using polycarbonate with signs as well, pointing to some of the same examples as Hogan, expanding on backlit options.
“Polycarbonate performs well in signs with traditional lighting and is compatible with LED light sources,” he says. “Some LEDs can show pinpoint light through the plastic sign face, so special LED grades should be used to avoid this ‘hot spotting.’ Polycarbonate is often used to enclose the backside of reverse channel letters. Polycarbonate has a higher index of refraction than acrylic, so should always be considered for lighting applications.”
It seems that lighting advancements have also had an impact on the structure of the sign itself, allowing for polycarbonates to be used more frequently.
According to Hogan, these improvements have “enabled the use of a much slimmer sign cabinet resulting in a much shorter distance between the lights and the diffusor sheet. This need for greater diffusion drove the development of polycarbonate sheets with improved additives, enabling a much better hiding power in LED applications.”
Cutting/Forming—Polycarbonates lend themselves well to cutting and forming. “Polycarbonates can be formed in a wide variety of ways,” explains Licklider. “They can withstand cold-bending, and unlike acrylics, polycarbonates can be bent in a brake press, eliminating the need for strip-heating in some cases."
In addition, he says, "Polycarbonate thermoforms easily and can be drape-formed or vacuum-formed. Polycarbonate should always be pre-dried before thermoforming to eliminate moisture.”
Thermoforming—the process of heating a sheet and then forming it into a specific shape—works extremely well with polycarbonates. Polycarbonates can be, “easily thermoformed with sharp detail on any conventional forming equipment capable of quickly transferring the sheet from the heating station to the mold or forming table,” says Millhof. “Rapid transfer is necessary because the sheet cools quickly and becomes form-stable at a higher temperature than some other sign materials.”
Polycarbonate is a versatile fabricating material as well, according to Hogan. “Polycarbonate sheets can be fabricated with standard power or hand tools for wood or metal, as long as they are well sharpened and have the clearance required for machining rigid plastics.” This is great news for smaller sign shops that may already have these types of tools on hand for other household projects outside of signage. Hogan adds that “table or portable power saws are suggested, including fixed blade bench saws, radial arm saws, circular saws and band saws. Shearing or punching are also possible.”
Other options include laser cutting or using a water-jet cutter, but these cutting methods are not used nearly as often.
Licklider says that, “a circular saw blade with carbide teeth using the ‘triple chip’ tooth design is a preferred method of cutting polycarbonate sheet. Table or overhead panel saws are normally used. Circular saws should be run in the speed range of 6,000 to 8,000 RPM.” He warns that sign makers cutting polycarbonates outside those speeds could run into serious problems.
“For best results, the highest possible speed that will not melt the sheet during processing will achieve the best results,” says Hogan. “High-speed steel tools are adequate in most cases. Carbide-tipped tools are preferred for continuous production lines. Tools should be set up so just the cutting edges come into actual contact with the fabricated material, to reduce frictional heat buildup.”
Printing—Just as polycarbonate can be shaped and formed into the vision of the sign maker, it can also include graphics using printing and other graphics application techniques.
“Polycarbonates can be painted, decorated with printed graphics, and transparent, translucent or opaque vinyl can be applied,” says Millhof. “Colors, tints, textures, and grades produced with tight shrinkage tolerances are all available as well, to broaden design and decoration options.”
“Polycarbonate is suitable for all printing methods which are applicable to rigid sheets, says Hogan, "but direct-to-substrate digital printing offers both time and cost savings, with excellent results.”
Most sign shops can agree that “time and cost savings” are about the best words in the English language. It keeps shops running efficiently and at a highly functional level. Even better, printing on polycarbonate can be completed at the highest level of quality.
“Clear polycarbonate sheets match the high clarity of other thermoplastic sheets, yet offer far better adhesion properties and ease of printing with no requirement for any further surface treatment,” says Hogan.
With all types of printing methods being practiced today, it’s important to note which can be employed with printing to polycarbonates. Licklider suggests that “polycarbonate can be successfully decorated using traditional printing methods. As digital printing starts to replace traditional print methods, polycarbonate remains a versatile material, eliminating the need in most cases for print treatments and corona applications.”
Put into Practice
Palram was recently part of a project to provide Alabama Wildlife Federation Museum’s NaturePlex with an enhanced educational facility for its guests.
“(It) was designed by Method-1 Interiors, a commercial interior design firm in Birmingham, Alabama, to amplify nature and provide both an immersive and memorable experience to its visitors,” says Hogan.
According to Hogan, the NaturePlex serves as the Welcome and Education Center for the Alabama Nature Center. The 23,000 square foot facility features a 120-seat theater with state-of-the-art technology; and also includes wildlife and nature displays, classrooms, offices, and a gift shop.
“Method-1 viewed this project as an opportunity to tell a story to a vast group of people spanning all ages while connecting to each of them in a unique way,” says Hogan.
One particular exhibit, the “Bee Hive Experience” had a prominent focus within the facility. Method-1 chose polycarbonate from Palram Americas to help bring it to life.
Hogan says Palram’s product was selected “because of its adhesion properties and for durability. They were searching for a substrate that not only had these properties but was also flexible enough for the intended use. The polycarbonate is printed with a simple honeycomb pattern on one side and a solid color was laid on the other side. Both sides of the polycarbonate were laminated to provide better protection on the exposed areas. Unlike a typical print, they felt this extra step was needed in this interactive environment intended largely for children.” The material was precision-cut using a CNC router, she says, because every layer of the bee hive carried a different shape.
“The design and lighting gives this otherwise simple product a captivating end result,” says Hogan. “Methods-1 utilized also used polycarbonate in other areas in the NaturePlex including some of the wall graphics throughout the area.”
It’s easy to stand up and say things like “this material is great” or “use this because it’s the best,” but seeing a project actually take form because a specific substrate was included—like polycarbonate—provides a resounding endorsement.
Millhof summarizes by saying, “We support our customers in achieving adventurous and demanding design challenges with value-added services.”
Marketable services for the many, many applications that include polycarbonates.