Durable labels involve some of the most challenging applications. Whether it be power tools or chemical drum labeling – or countless other segments – a durable label is required to withstands the harshest of environments.

Adhering to an object in the presence of extreme moisture, temperatures, UV light, chemicals, and more are hallmarks of durable labels. Plus, these labels must exhibit high peel, tack, and shear to high and low surface energy substrates.

“Durable labels should possess temperature and weather resistance, functioning effectively in both hot and cold conditions,” notes Melissa Harton, marketing manager, North America, Fedrigoni Self-Adhesives. “They must endure challenging environments, exhibiting chemical and UV resistance. Additionally, force resistance, such as resistance to abrasion or tearing, is crucial. Waterproofing is also essential, benefiting both the label’s performance and print quality.”

There is a significant safety component to durable labels, too. “The label must remain legible and adhere to the surface for the life of the product, thus protecting users from injury by providing information on safe operation, as well as protecting manufacturers from liability,” states Jason Berthiaume, product manager, Flexcon. “Many durable labels are subjected to stringent UL 969 standards.”

How critical is a durable label’s effectiveness? “A missing label – and consequential lack of information – can result in injury to the user, subjecting the manufacturer to liability,” adds Berthiaume. “Label failure can also impact the brand in terms of aesthetics, reliability, and reputation.”

“If a label indicating hazardous materials were to fall off, it could result in serious injuries or even fatalities, particularly when dealing with substances like flammable materials that may not be readily identifiable,” adds Harton. “An ineffective electrical warning label can also pose serious risks. Beyond the immediate safety implications, such failures may lead to regulatory fines or legal actions due to non-compliance.”

The label transcends the substrate, as well. The ink must play its part in these applications. “If, for example, the ink fails on a safety label in a car or on an industrial machine, certain safety hazards may not get communicated to the operator,” explains Mark Hill, senior VP and director of R&D, INX International Ink Co. “Safety, in general, plays a significant role for durable labels. In some cases, those labels need to be replaced before the equipment can be used. In other cases, if the label fails, it simply could mean the product conveys it is less ‘premium’ and the company could lose market share because a brand’s label is not visible anymore.”

Plus, don’t forget to match the appropriate adhesive with the right substrate. “One challenge involves selecting the right adhesive for durable labels and matching it with a suitable substrate,” explains Harton. “Durable label substrates include synthetic materials like polypropylene, polyester, polyethylene, and vinyl. The adhesive must be sufficiently aggressive to adhere to diverse substrates without experiencing flagging or detachment.”

According to Laurel Loy, associate product manager, Mactac and Spinnaker, durable labeling is often talked about with GHS. GHS translates to a Globally Harmonized System and refers to a worldwide United Nations-driven system of classifying and labeling chemicals.

“This system uses standard, predetermined classes, statements, and symbols called pictograms to communicate information about safety, human health, and storage – and UL approval, if required,” says Loy. “GHS information can be challenging due to balancing product identification and information and including the proper GHS information. Often, customers don’t want the label to be too busy in most situations. For inventory label purposes, consumers do not want to have to read an abundance of information, but often it might be required. The most popular market seems to be the chemical and oil drum market,” adds Loy. “Chemical labeling typically requires the label to be BS5609 approved along with a three-month sea and saltwater submersion test.”

British Maritime Standard BS5609 is a drum and barrel test designed to certify that a label will stay affixed to a drum for at least three months in seawater so that the contents are identifiable in the case of a shipwreck. Loy notes that BS5609 only tests and certifies drum labels, not other chemical containers or products.

“Underwriters Laboratory (UL) is another vital entity for durable label testing, aligning with the American National Standards Institute (ANSI),” remarks Harton. “This is particularly relevant for electrical, electronic, and related technologies, where labels must include hazards, warnings, instructions, and electrical ratings. Materials used for labels are tested in accordance with ANSI/UL 969, category PGGU2.”

While chemical drum labeling is often the first application to come to mind with durables, the segment includes a wide range of applications. “Some durable labeling includes general product identification and UL labeling for appliances and electronics, laboratory specimens, and outdoor applications for nurseries and agriculture,” remarks Loy. “Durable labels often label very sensitive materials, and you want to make sure you are learning as much information as possible from customers to make sure the most appropriate material recommendations can be made.”

The testing process is quite rigorous, as manufacturers must anticipate any number of possible chemicals that can come into contact with the label. “Label materials must be tested for all anticipated exposures,” comments Berthiaume. “This may include chemicals such as gasoline or oil splash, high-temperatures, abrasion during the manufacturing process, transport and use, and exposure to UV and inclement weather.

“All of these situations create challenges for inks, adhesives, and the label substrate,” adds Hill.

For many markets, label materials must undergo rigorous testing following protocols set by UL 969, automotive and/or other standards. Notes Berthiaume, “This includes testing of the film and adhesive for adhesion to the applicable surface, as well as testing of the topcoat for ink adhesion, print legibility and durability when subjected to the aforementioned exposures.”

The durable process

There is a labor-intensive process associated with durable label construction. According to Amy Donato, PPG’s global platform director, TESLIN substrate, there are a few key considerations. The entire labeling process and supply chain must consider the specific conditions the label will be subjected to in order to prevent such risks and ensure overall safety and effectiveness.

“First, it’s crucial to understand the surface the label will be applied and the environmental conditions the item will be subjected to during its usable life,” says Donato. “The compatibility between the surface, adhesive, facestock and environment is vital for long-term durability.

“The second area of consideration is knowing how the packaging will be disposed as this helps determine which type of sustainable label material to use – whether it be recyclable, compostable or biodegradable,” she continues. “The label material should be compatible with the disposal method to ensure that the product can be disposed of in an environmentally conscious manner.”

Another area for consideration is the print method that will be used. “Different durable facestocks may have limitations regarding compatibility with various printing technologies,” explains Donato. “Therefore, selecting a facestock that aligns with the chosen printing method is essential to ensure a successful and durable label construction. Overall, achieving harmony between surface characteristics, adhesive properties, disposal methods and printing technology is fundamental to addressing the challenges in the development of labels for the durable label space.”

After constructing the facestock, testing is crucial. “Typically, companies set label specifications, and BS5609 is regarded as the gold standard for labels to withstand harsh elements,” comments Donato. “Brands may have unique requirements, including specific chemical tests tailored to their needs. The testing process involves collaboration within the supply chain, with close coordination between brands and label converters to ensure the chosen label construction aligns with the intended application.
PPG’s strong partnerships with customers facilitate collaborative problem-solving.”

Plus, PPG actively collaborates with customers’ R&D teams to explore new solutions, emphasizing the essential role of this cooperative approach in meeting unique and stringent customer requirements.

A durable evolution

The advancement of new printing technologies has required suppliers to innovate with their latest materials. For example, the proliferation of digital printing has necessitated materials that meet durable demands while printed with water-based inkjet equipment. Historically, converters only relied on a select few materials such as vinyl and polyester.

That list has grown exponentially over the years.

“Vinyl film has always been prominent in the durable label space where long-term outdoor exposure is required,” explains Mactac’s Loy. “We all know that vinyl can be tricky to work with and convert. More durable film variety has become prominent in the industry, as you now have more polypropylenes with varying degrees of outdoor life. And the same goes for polyolefin and polyethylene on the market currently.”

Vinyl is economical, as well as being flexible for conforming to product contours. Polyester is also popular due to its resistance to high temperatures as may be experienced in automotive and aerospace applications. It is also very smooth and, therefore, enables high graphic quality.

Durable polypropylene has made inroads, as well. “Durable polypropylene is now becoming popular as a less expensive alternative to vinyl, which has been undergoing scrutiny from an environmental standpoint,” remarks Flexcon’s Berthiaume. “Polypropylene can look, act and feel very similar to vinyl, and some polypropylene films carry the same five-year outdoor durability warranty as outdoor vinyl films. Unlike vinyl, it can also be laser diecut, affording printers more versatility.”

In terms of digital printing technology, substrate suppliers have made strides here, too.

“The increasing popularity of digital print technologies has given rise to advancements in topcoat technology,” says Berthiaume. “With new inks and curing methods being developed, the topcoats used on films must advance as well. Hybrid presses have necessitated the development of topcoats that are compatible across multiple print technologies.”

The environment is a key concern with durable labels. “On the sustainability front, there is a comprehensive shift beyond just the label itself,” remarks PPG’s Donato. “The focus extends to the entire manufacturing process, embracing a cradle-to-grave approach. The number of companies in the paper and packaging industry committed to science-based targets has rapidly increased from five companies in 2019 to 164 in 2022. Efforts are being made to develop durable labels with less plastic content and are biodegradable or compostable. Biobased content is also gaining prominence as part of sustainable label technology.”

The latest in durables

Suppliers have delivered a host of new products to meet demand for the toughest labeling segments.

Fedrigoni Self-Adhesives (FSA) offers a wide variety of products designed for the durables market in North America. The company’s range includes materials that have been crafted for warning labels, particularly those applied to chemical drums with BS5609 Section 2 and 3 compliance.

“Additionally, we provide specialized materials for batteries featuring high-performing self-adhesives capable of enduring surface heat,” says Harton. “Our product line extends to polyester label materials suitable for UL-recognized items, ensuring compliance with the UL 969 standard. We also offer label materials designed for inner motor applications, characterized by their need for high-temperature resistance and optimal performance in the presence of oil or grease.”

Flexcon has also launched Flexcon Nexgen, a primary line of products ideal for durable labeling in the consumer durables, transportation and industrial spaces.

The 30 products in this Flexcon line consist of polyesters, polypropylenes and vinyls that offer versatility to meet a full range of applications, including compliance labels, brand identity labels, and warning/instructional labels.

“In addition, Flexcon DPM Aply products, consisting of durable polyesters, vinyls and polypropylenes with air egress liner, ensure bubble-free label application,” states Berthiaume. “Finally, Flexcon DPM overlaminates offer protection of label graphics from a multitude of exposures, including UV, with exterior durability ranging from 2-10 years. Certain products are available in custom widths with no up-charge through the Flexcon FlexChoice program.”

Combined, Spinnaker and Mactac offer a strong portfolio of items that help meet a wide variety of durable applications. “The adhesive variety available with our Durable faces in Precise and Trimless form is unmatched,” explains Loy. “Whether it’s the 3.3 Durable Polypropylene at Spinnaker that can last two years outdoors or the UL approved portfolio of items available through Mactac, we can help tailor very customized solutions that are typically very easy to buy.”

Meanwhile, PPG TESLIN substrate is a durable, secure, and highly printable synthetic paper that excels in applications that demand a tough, high-performance material. TESLIN substrate can be used across a broad array of applications when durability is needed. It has the ability to protect printed data while providing enhanced flexibility in print technology compatibility, as well as high-quality text, photo, and color reproduction.    

“TESLIN substrate absorbs and locks inks and toners into its structure to secure printed text and images, rendering printed data practically impervious to abrasion,” says Donato. “Many other synthetic papers, inks and toners must cure on top of their surface, making printed information vulnerable to damage or removal.”

Additionally, PPG TESLIN substrate is compatible with print technologies ranging from offset and flexo to inkjet and laser. It is digital print-ready right out of the package – no corona treatment, topcoat, or varnish is needed. It is also effective in dissipating static build-up.