Behind the Scenes
Adhesives have a thankless job. Unlike specialty inks or innovative packaging, adhesives tend to go unnoticed by consumers. But, they discreetly carry an enormous amount of responsibility to reliably bond a wide range of substrates.
Because adhesives have to work with such a diverse spectrum of materials, many times they are tailored to specific applications. For instance, adhesive trends have been influenced by the use of package decoration materials that originate from sustainable resources, says Philip Emery, director, applied surface technologies, FLEXcon.
“PLA film, which is created from corn rather than petrochemicals, as a packaging-grade plastic, is a notable example,” he says. “Adhesives are now being defined that will allow these materials to flow smoothly into labeling applications. Benefits unique to individual end-use applications derive from the use of lower surface energy materials, but this also represents one of the more difficult substrates on which to achieve an adhesive bond.”
Environmental and cost-saving issues have dictated what type of adhesives to consider. “Gas prices are at an all-time high and there is a shortage of refinery capacity. Solvent-based adhesives waste valuable natural resources and are becoming cost prohibitive,” says Steve Bergerson, technical director, ADMTronics. Instead, water-based, environmentally friendly adhesives are gaining popularity in the industry.
Besides looking out for Mother Nature, adhesives can help your bottom line, if you know which are most cost-effective for your packaging job. “Here you have to look at the per-square-foot cost and not just the price as supplied,” says Bergerson. “Another consideration is process cost. Water-based adhesives can be wet-laminated to porous substrates with no energy usage to dry off the solvent or to hot-laminate the construction.”
But, even if the price is right, the adhesive could be wrong. “Converters should always consider their substrate and what kind of adhesive is needed to work well with that substrate,” says Shirley Monte, business development manager, performance products business team for FLEXcon. “Then they should consider the environment the package is going to live in. Answer these before considering whether it is best to use a water-based acrylic adhesive or solvent-based adhesive.”
Working with film suppliers can help hone in on these answers, says Rick Harris, product manager, product branding business team, FLEXcon. “Printers should rely heavily on the expertise of the pressure-sensitive film supplier. They should share all the requirements for the adhesive performance with their PS film supplier. The PS film supplier will also need to know the film type, printing process, diecutting process, handling and dispensing methods, and environmental requirements,” says Harris. “All of these factors combined will give the PS film supplier a road map for recommending the best choice of adhesive that will perform to the needed requirements without problems.”
The following are adhesives that put in a lot of time behind the scenes.
Cold foil lamination adhesive
UVitec’s 21303-87 cold foil lamination adhesive is designed to cure through opaque lamination film. The lamination occurs after a base substrate and lamination film are passed through a nip point and then cured; a rewind roller removes take-off foil. This product aims to provide a sharp image area suitable for small point type as well as a strong bond for large area applications. It is also available with optical brightener for applications in which a clear lamination film is being applied.—UVitec, www.uvitec.com
Poly-aqueous adhesive
POLY 6LXW72874 is a water-based adhesive formulated to provide adhesion characteristics and product resistance on polyethylene-coated board containers. It is designed for ease of application, resolubility, and controlled release in the production of milk, juice, and food cartons.—Color Resolutions, www.colorresolutions.com
Craigbond 3991 series
Craig Adhesives & Coatings’ Craigbond 3991 series is a water-based repositionable product line that allows a label or glue flap to be removed or opened and later reattached or closed while producing no fiber tear. The adhesive material in the series is a high-tech water-based formula designed for easy application with flexographic, screen, or extrusion devices, and yields a non-destructive bond on a variety of substrates. The system most commonly employed uses Craigstick 3991PLV and Craigcoat 6960CLR water-based release overprint varnish. Both formulations are designed with mileage, adhesion/release, wide operating windows, cleanup, and value-added performance in mind.—Craig Adhesives & Coatings,
www.craigadhesives.com
UV cold foil adhesive
Water Ink Technologies’ new GlossSeal CFA is a UV-curable cold foil adhesive for cold foil decoration and holographic transfer products, featuring through-cure, which helps to achieve a clean release for crisp, sharp edges. The GlossSeal CFA adhesive is part of the company’s complete line of safer UV inks and coatings that includes UV inks for high definition printing, UV shrink sleeve inks, and silicon-free UV rotary screen inks.
—Water Ink Technologies, www.waterinktech.com
FLEXcon’s no-label-look
The new A-208 permanent pressure-sensitive acrylic adhesive provides “water-clear” wet-out on glass and polyester containers and resists hazing during pasteurization and ice chest. It is designed for price-sensitive beverage labeling applications, used in combination with FLEXcon’s optiFLEX line for “no-label-look” graphics.—FLEXcon, www.flexcon.com
Water-based primer
ADMTronics’ Aquaforte 108W is a general-purpose primer with properties for extrusion coating, including Low Density Polyethylene (LDPE) to Polyester (PET) or aluminum foil. The product’s high grease and oil resistance makes it suitable for snack packaging and labeling applications. Aquaforte 108W also possesses excellent moisture resistance, making it applicable for many food packaging needs.—ADMTronics, www.admtronics.com
Flexible packaging adhesives
Ashland Inc.’s PURETHANETM and PURELAM adhesives for flexible packaging can be used for dry- or wet-bond applications, packaging films, frozen or refrigerated packaging, film-to-film and film-to-paper laminations, heat-seal coatings and vacuum laminations. The PURETHANE adhesives are also used in industrial laminating, reflective insulation packaging, and electrostatic discharge packaging applications.—Ashland, www.ashland.com
Freezer-grade hot-melt adhesive
EASY-PAC C is a low-temperature freezer-grade case and carton sealing hot-melt adhesive. It has an operating temperature range of 212°-225° F and adheres at temperatures of -20° F and potentially lower, depending on the substrate. The adhesive is intended for use in consumer ice cream, dairy, and poultry packaging. EASY-PAC C is sold with the EASY-PAC Package Sealing Solution, a complete system that National Adhesives developed for case and carton sealing applications in food processing, beverage, personal care, household, industrial goods, and consumer electronics industries. The system comes with a hot-melt dispensing unit that includes an integrated autofill vacuum feeder, hoses, nozzles, modules, and a hot melt storage bin.—National Starch and Chemical Company, www.nationalstarch.com
