By Melissa Donovan
Polyvinyl chloride (PVC)-based overlaminates are general purpose protective and enhancement materials used for a number of applications. This includes wide and narrow format digitally printed projects from floor graphics to brochures. Besides PVC, other options include polyester, polyurethane, polyethylene terephthalate (PET), and polypropylene (PP) laminates.
The existence of non-PVC options answers the demand for a lower cost alternative, as well as a more sustainable product compared to PVC. These are considered specialty laminates in some instances, although some material compositions enable the non-traditional overlaminate to offer features similar to PVC. Despite these developments, PVC-based overlaminates remain a dominant player in enhancing and protecting graphics.
Above: Drytac Protac Anti-Graffiti is a high-gloss PET film with an anti-graffiti coating on the surface.
Overlaminates have a rich history. Some of the first were thermal polyesters primarily used to protect or encapsulate paper-based products. As print capabilities evolved, so too did materials. PVC-based overlaminates were introduced as a way to protect inkjet printed graphics.
“PVC-based films are primarily used with pressure-sensitive adhesive (PSA) or cold lamination, because PVC or vinyl cannot accept the high heat required for more traditional thermal or hot lamination. PSA lamination gained acceptance with the advent of digital inkjet printing onto PVC substrates. The early print engines used aqueous inks, which boiled under the temperatures required for thermal lamination, and the vinyl substrates warped. PVC-based film, utilizing an adhesive that activates with low or no heat, grew in popularity as the inkjet market matured,” shares Mitch Noble, managing partner, Graphic Finishing Partners, LLC.
Jeffrey Stadelman, marketing manager, Mactac, explains why PVC has always been the de-facto standard for overlaminating film. “It offers a relatively low-cost option for the sign/graphic manufacturer. Additionally, it is easy to handle through a laminator or when wrapping a vehicle. It is the best option for flexibility to go through anything from simple to complex curves. Manufacturing-wise, it can be designed for short- to long-term exposures, developed in a variety of finishes, and formulated in a number of different levels of quality, thickness, and durability.”
Due to its flexibility as well as stability, cast overlaminates are ideal for long-term applications, especially with curves. “For vehicle wraps and other applications with compound curves, cast vinyl overlaminates offer the conformability and flexibility necessary during installation, while still providing excellent UV protection to the underlying graphic,” advises Bekie Berg, product manager, FLEXcon.
Conversely, calendared vinyl is manufactured though a rolling process. “This is more stressful on the vinyl and results in less dimensional stability. Calendared vinyl films are generally thicker than other laminating films, which allows the surface to be embossed, creating textures for different applications,” says Noble.
The limited dimensional stability makes calendared overlaminates ideal for shorter term applications. According to Berg, this includes graphics applied to flat surfaces or simple curves.
In general, PVC overlaminates serve two main purposes—to enhance and protect graphics. “Graphics with vivid colors become much more vibrant with the use of an overlaminate. With different finishes, graphics can be enhanced to complement the environment, reflect light, or take on a look of media. Additionally, overlaminates preserve and protect. They can protect against UV rays to preserve the longevity of a graphic in a window or in light. They can prevent scratches and scuffs to help trade show graphics last for years. Overlaminates also offer more specific protection including slip resistance,” says Edwin Ramos, national sales manager, GBC & SEAL.
Polyester, polyurethane, and PP overlaminates are considerations when looking to enhance or protect digitally printed graphics. Each offers its own advantages. For example, the chemical composition of PP makes it more eco-friendly compared to PVC. Polyurethane offers a high stretch rate, suitable for complex curves. Polyester provides a greater level of durability, further protecting a graphic.
“Various non-PVC overlaminates on the market include PP, PET, polyurethane, polyester, polycarbonate, polyolefin, and polyvinylidene fluoride. These materials may satisfy certain application requirements better than PVC. For example, some materials provide enhanced durability and UV resistance in harsh environments. Other materials provide better abrasion protection, much like paint protection film, which is made from polyurethane,” shares Adrian Cook, marketing manager for digital print films and overlaminates, 3M Commercial Solutions.
Environmental concerns are key to these product introductions. “New products such as PP and polyester overlaminates are becoming popular because they are often more environmentally friendly and adhere better to certain types of inks and/or substrates,” explains Ramos.
“Sustainability is a global trend and the demand for ‘greener,’ more environmentally friendly products continues to grow,” agrees Berg. “PP, for example, contains only two elements—carbon and hydrogen—unlike PVC, which contains chlorine and plasticizers or phthalates. PVC is more harmful to the environment than PP while it is being manufactured and after it has been disposed.”
Recyclability and regulations such as Prop 65 drive demand for these newer substrates, according to Steve Yarbrough, product support specialist, Drytac.
Polyester overlaminates are attractive for buyers looking to improve performance or reduce cost, according to Brian Biegel, marketing communications specialist, D&K Group, Inc. “They offer a durable surface that is harder than PVC. Polyester films are available with special topcoats that offer sophisticated characteristics such as graffiti resistance, dry erase properties, and velvet. Certain polyester films can also be printed or spot coated to create a unique look that grabs attention and creates a high-perceived value.”
Polyester-based products offer scratch resistancy, and many vendors are able to translate the redeeming qualities of polyester into PET versions. For example, Lintec of America recently developed a matte/satin PET material offering anti-graffiti properties as well as repels spray paint.
Polyurethane laminates offer attributes that are major improvements over traditional PVC cast overlaminate films, explains Josh Culverhouse, graphic innovations market manager, ORAFOL Americas, Inc. “They are resistant to yellowing and cracking over time, specifically on horizontal applications. Self-healing properties against light swirl marks and scratches; as well as a higher stretch rate compared to traditional PVC cast film, make it ideal for complex compound curves or recesses.”
“Many manufacturers do not offer a warranty on horizontal applications when using a traditional PVC laminate in harsh environments. Polyurethane on the other hand is a material with improved durability and horizontal warranty in harsh climates,” adds Joshua Barnard, product manager, Avery Dennison Graphics Solutions.
PP usage in particular derives from the flexographic market. Vendors in the wide format space have gone a step further and introduced linerless product lines, which offer added green and efficiency benefits.
“Flexographic houses print onto non-porous substrates like PP, and they used a low-cost, high-speed, self-wound, or linerless base film for decades,” shares Noble. Linerless PP product lines advance sustainability. With no liner, a film can run at twice the speed of a liner-based material, is half the cost, and 40 percent the shipping weight of traditional PSA films, he adds.
Also referred to as self-wound films or overlaminates without release liners, linerless laminates are also environmentally friendly because there is no liner to throw away, states Daryl Hanzal, president/CEO, Global Graphic Resources. “They are easier to handle since they are lighter weight and easier to store because the rolls are usually smaller in diameter and more fit on the shelf.”
There is a demand for linerless PP films. As Noble states, it comes from the desire for a low-cost, short-term coating solution similar to liquid coaters. “They are also growing in popularity with the advent of flatbed applicators and flatbed printers. Applicators generally do not use a rewind tool to remove the liner from traditional PVC-based films. These new linerless films make the hand application process much easier,” he continues.
PP overlaminates without release liners eliminate rewind stations. “This makes loading and webbing the laminator fast and easy. The lack of a release liner and need for a rewind station also allow the user to load a second roll of laminate on the lower material station of their laminator. This gives the user the ability to laminate the top and bottom of a graphic in one pass using pressure-sensitive material,” adds Tony Caruso, Eastern regional sales, Advanced Greig Laminators, Inc.
Dragan Nikolic, business development manager, Nobelus, says manufacturing PP can go a step further, making the PP laminate more stable, stronger, and improve its clarity. “This converting process creates a bi-axially oriented PP (BOPP) and is basically done by stretching the film on the X and Y axis. BOPP accepts electrical charges called corona treatments that increase surface tension or molecular activity, resulting in greater compatibility to embellishments, print enhancements, and modern finishing processes.”
Non-PVC overlaminates are used in many different applications, depending on the goals of the end user including whether it is a short- or long-term project and if it will be placed indoors or outdoors. Compared to PVC, which is a general use, jack-of-all trades product, non-PVC is considered a specialty option.
“In some cases, overlaminates target the same applications, such as vehicle wraps and exterior signage. In other cases, the overlaminates may have a specialty application, like providing anti-graffiti properties. Many of the applications for non-PVC overlaminates are niche, such as dry erase film,” points out Cook.
More non-PVC overlaminates pursue indoor advertising applications, according to Berg. This includes retail displays, point of purchase (POP) displays, counter graphics, and trade shows/event graphics.
PP film, specifically linerless, is suitable for short-term or indoor applications that only require up to one year durability, according to Noble., “Exposure to UV causes PP to yellow and turn brittle over time. But it provides resistance to chemicals, environmental agents, and protects against scratches to any inkjet print for indoor applications.”
Robert Rundle, marketing manager, Nekoosa, agrees that PP products are short-term options. “They are usually short term and slightly less expensive alternatives to vinyl overlaminates. Most PP laminates are for indoor use only and don’t have UV inhibitors to help the inks from fading.”
“PP is frequently used for single-sided lamination applications such as leaflets and posters or where added durability is needed against oils and minerals, while polyester film is frequently used for heat-resistant applications where scuff and scratch resistance is needed such as trade show graphics,” shares Ramos.
BOPP films offer tactile surfaces—soft touch, leather, and linen—attractive to brands in the consumer packaging industry, which makes them ideal for use in folding cartons, labels, and flexible packaging. “Brands and their designers seek ways to stand out or appeal to a certain demographic and audience. BOPP helps brands differentiate on the shelf and increase the perceived value of the product within the package,” says Nikolic.
Biegel believes newer overlaminates generally target either low-cost projects or those requiring advanced performance characteristics. Polyester for example may be used for signs or other prints exposed to the public since polyester is a strong plastic that can withstand wear and tear.
“Polyester thermal laminates provide clarity, strength, and resistance to abrasion, water, oil, acid, and alkali. They are well suited for high-production runs on bond inkjet paper, microporous-coated inkjet paper, electrostatic, and continuous toner photographic prints,” adds Kara Work, product line manager, S-One Holdings Corporation.
Polyurethane laminates are used for long-term general signage and even vehicle wrap applications. “Certain polyurethane overlaminate offers long-term graphic protection for commercial and fleet wrap applications, illuminated backlit signage, and general signage applied to aluminum. It provides maximum protection in tropical, arid, extreme cold, and industrial environments,” explains Culverhouse.
There’s a Place
While newer overlaminates disrupt the market, traditional PVC-based laminates will always be in demand. This includes a number of reasons ranging from cost and compatibility with ink to application requirements.
“Traditional overlaminates are attractive. They are cost effective for everyday jobs where basic protection is needed. Also, some overlaminates don’t adhere well to every substrate or ink,” admits Ramos.
Cook suggests that PVC is still the dominant material used in overlaminates. “It satisfies the majority of needs at a competitive price point. Compared to PVC, there is a trade off with using an alternate material overlaminate—either in cost or performance—some materials may have a lower cost but lower durability. Others have higher cost but higher durability.”
“Not all applications require the performance benefits of newer overlaminates and the cost that comes with those. If a traditional laminate will fit the needs of the application then there is no need to use a more expensive product in its place,” suggests Barnard.
Specific applications still need a PVC-based film, primarily for their thickness. “A PVC-based substrate is two or three times the thickness of linerless films, so applications like floor graphics still need a thick PVC-based substrate to hold the surface texture. Thicker films also provide body or rigidity to the print for better handling or display purposes,” advises Noble.
“There is still a place for traditional PVC overlaminates, especially for outdoor applications. Signs and similar applications may require a two to three year outdoor durability that PVC offers,” admits Biegel.
Berg agrees. “Non-PVC overlaminates do not offer the outdoor durability that PVC overlaminates provide for long-term outdoor graphic applications.”
Rundle says there is a preference to keep calendared vinyl laminates on calendared vinyl media and cast on cast. “Moving to a new film laminated to vinyl is associated with a risk and must be tested prior to production runs,” he shares. Matching a PP laminate with a PP base media isn’t impossible, but can be challenging.
That said, the drive to newer products like PP, PET, and polyester will be the green factor, shares Yarbrough. “It all depends on the market and degree of protection a graphic needs as well as customer specifications. Different applications will need different protection factors.”
“As companies become more eco-friendly and look for ways to protect graphic prints they lean toward non-PVC laminates. Also, a large percentage of the digital market is for POP and shorter term graphics, so PP films are the answer,” adds Hanzal.
Meet the Requirements
Traditional PVC overlaminates are ideal for any application that requires protection, preservation, or enhancement. This range of compatibility is PVC’s strength.
While non-PVC overlaminates like PET, PP, polyurethane, and polyester cannot compete with PVC’s application breadth and deep range, each offer advantages and are worth considering when it comes time to choose an overlaminate.
Feb2020, Industrial Print Magazine