Lin Lin  
Validation Engineer
Smith Corona Corporation
5 years with the company
(800) 875-7000

Todd Hunt 
Director of Business & Technical Development, PSAs
Franklin Adhesives & Polymers
24 years with the company
(614) 443-0241

Q: What’s new when it comes to your company and adhesives? Have you introduced anything recently? Are you planning any releases that you can discuss?

Lin: In 2014, beginning with our first general purpose formulation, Smith Corona started producing its own adhesives in house. In February 2017, Smith Corona introduced a new freezer adhesive specifically formulated to withstand frozen and deep-freeze applications. This adhesive adheres to a variety of packaging materials and is designed to endure the harshest conditions present in the cold-chain supply line. Our freezer adhesive is a rubber-based hot melt that has a high initial tack and quick adhesion to a variety of substrates. We have other developmental formulations in the works, but nothing is slated for an immediate launch.

Hunt: Franklin Adhesives & Polymers has been focused on the development and commercialization of new, high-performance green PSAs. We recognize that global regulations continue to tighten and our chemistry options for design and development are diminishing. Therefore, we have recently developed four new APE-free, formaldehyde-free and pH neutral PSAs for the tape, label, graphics and packaging markets.

Covinax 599-01 is a REACH-compliant, high-performance general purpose permanent for tape, label and packaging. Covinax 289-01 and Covinax 289-02 are REACH-compliant, all-acrylic, all-temperature PSAs for tape, label and cold packaging applications. All three of these products have been designed for adhesion and anchorage to difficult low surface energy facestocks. They are extremely mechanically stable and can be high-speed coated, even curtain-coated, which improves production efficiencies and lowers the coater’s costs to produce. The third product is a unique, high-performance ultra-removable PSA for the label, graphics and surface protection markets. Covinax 320-01 is also REACH-complaint, containing no substances of very high concern (SVHC). Its intrinsic proprietary cross-linking system provides for a final film that is moisture- and chemical-resistant and optically clear, with aging properties that even rival higher cost solvent-based PSA performance. Covinax 320-01 provides for smooth and completely clean removability with no adhesive transfer or ghosting, even after extended heat aging on glass or metal.

Q: Solvent-free or solvent-based: Explain the pros and cons to each type and the potential future of product considerations moving forward.

Hunt: As regulations and health and safety concerns come to the forefront of the development and design of adhesive products, we see solvent-based products being phased out and replaced with solvent-free or water-borne adhesives. Volatile organic solvents also receive quite a bit of scrutiny by government agencies and are increasingly regulated. Though solvent-based PSAs have been considered the Cadillac for performance in the industry for decades, water-based and solvent-free chemistries are quickly catching up and sometimes even surpassing traditional solvent-borne products.

In addition to being more environmentally and employee-friendly than solvent-based products, water-based technologies are much cheaper both in upfront and processing costs. Additionally, water-based products are generally extremely mechanically stable, which allows for ultra-high-speed coating, further lowering operational expenses versus solvent-borne offerings.

Lin: Solvent-free adhesives, such as hot-melt adhesives, have become the preferred type of adhesive industry-wide. With our newest adhesive, we chose a solvent-free hot-melt formulation that has the capacity to withstand changes in environmental conditions. We see the use of high recycled content corrugate as a positive for all, but the more recycled content, the more difficult it is to adhere. The high tack and affinity of the hot melt for the fibers of the corrugate make it the appropriate choice for this application. A negative aspect of these types of hot-melt adhesives is that they are not repositionable and will be permanent once applied. Hot-melt adhesive is the most appropriate choice for consumable labels used in case identification and shipping labels.

Solvent-based adhesives are becoming less prevalent, but are still used for some specialized applications. Solvent-based adhesives have the best adhesion to a wide variety of substrates, and are suitable for drum, medical and durable applications, where increased resistance to chemical interactions is required or where long lasting labels are necessary. The downside of solvent-based adhesives is that they are not environmentally friendly, require solvent removal and there is a possibility of residual solvents that pose a health risk throughout the label’s life cycle. As a result, health and safety concerns must be addressed in order to remain in regulatory compliance.

Smith Corona is dedicated to sustainable and environmentally friendly practices. Our hot-melt adhesives are composed of roughly 50 percent plant-based materials, making them a more sustainable adhesive than acrylics or solvent-based products. Solvent-based adhesives are in decline industry-wide and we have no plans to use them. The future is in solvent-free adhesives, and that is where we will continue to focus our efforts.

Q: Regulatory compliance is a complex issue that many companies need to consider. How does this play into adhesive development, and how well is your company suited to meet global regulatory demands?

Hunt: Regulatory compliance is one of, if not the most important consideration, when designing and developing new adhesive products. Although it remains to be seen what recently enacted reforms to the Toxic Substance Control Act (TSCA) will actually mean in practice, regulations continue to increase around the world. Today, a developmental chemist has fewer and fewer tools to work with for polymer and adhesive design. Even though a specific chemistry may not be officially banned, the chemist is forced to move away from those substances that may be under scrutiny or on a watch list for fear of further regulation later. REACH has placed a severe limitation on the chemistries that can be used for polymerization and subsequent product formulation for the European market. Even though REACH is solely a European regulation, REACH guidelines are now surfacing in other countries, such as Canada and China, and the policing of the regulations seems to have amplified. Even though an adhesive company may only sell domestically in the U.S. or another non-EU country, concerns for the end product finding its way into the European market loom for downstream customers. Thus, REACH becomes a de facto global regulation requiring very close monitoring of the amount of certain chemicals entering the EU and ensuring that all SVHCs contained are fully registered.

In water-based PSA development, the largest concern is the regulation of alkyl phenol ethoxylate (APE or APEO), a common and widely used surfactant in water-based PSAs. This material is now considered a SVHC since it – even though harmless to humans – is considered a reproductive toxin to aquatic animals. Franklin Adhesives & Polymers is now using alternative surfactants for the development of water-based PSAs. Though these alternatives are not a simple drop in replacement to legacy surfactants and require an entirely new polymerization process, we have had very good success in the development of new APE-free PSAs. As a company, we are gradually replacing our APE-containing legacy products with APE-free offerings without sacrificing and sometimes even improving performance properties.

Q: Is there anything else you’d like to share about your company or adhesives as it pertains to flexible packaging?

Lin: Because Smith Corona is backward integrated, we have developed an intimate knowledge of how our papers and adhesives perform best together. We use this knowledge to make sure our customers buy the products best suited for their particular needs across a wide range of packaging and warehouse applications. Combining our product knowledge with our customers’ needs has allowed us to develop a wide range of standardized products that can ship the same day. Furthermore, because we control all aspects of production within one facility, we can respond to the specialized needs of our customers at a moment’s notice. We typically save our customers 30 percent on their labels because we manage all stages of production and quality in house.