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Sustainability and environmental concerns combine with regulatory requirements and technical performance to shape the formulation of adhesives for today’s packaging and converting markets

Environmental and sustainability concerns are now a major consideration for adhesives manufacturers such as BASF, which recently gained a further TÜV certificate (DIN Certco) for its Epotal ECO compostable adhesive. The water-based biodegradable adhesive first gained the DIN Certco for compostable additives in 2010. It now offers higher adhesion levels by combining the dispersion with a special curing agent. Tests show that within 70 days Epotal ECO is 90% decomposed, leaving no toxic residues or negative effects on the environment. In addition, says BASF, it retains all the advantages of water-based adhesives – high green strength and absence of any toxic substances.

The first bio-based compostable adhesive in Dow Europe’s portfolio, Adcote BL 1001-BCR1001 is said to be “both efficient and sustainable” for a range of flexible packaging applications, including dry foods and snacks. Enabling converters to deliver compostable structures and brand owners to respond to increased demand from consumers for more environmentally-friendly packaging, this new adhesive also offers an improved biodegradability compared with cellulose.

Market concerns

Dow has also expanded its range of solventless adhesives with two new Mor-Free coreactant products. L716-FB+CR121 offers users higher line speeds, easy handling and a faster time to market for a wide range of packaging applications requiring general to medium performance, such as dry goods, snacks or confectionery.

Mor-Free ELM L425+CR78-550 can combine extreme low monomer technology with fast curing for many applications with medium to high performance lamination requirements. Dow says it helps reduce the environmental impact of the lamination, generating 87% less CO2 emissions and 85% less energy consumption than solvent-based solutions.

A particular area of market concern is the use of solvent-based vinyl lacquers, particularly on aluminium foils. Use of vinyl chloride monomer is limited to a 1mg/kg SML (specific migration limit) in all direct food contact applications on a pan-European basis. The presence of residual solvents from these lacquers can also have a detrimental effect on both organoleptic properties and food safety. In response, Paramelt has introduced new products in its Aquaseal range of water-based heatseal and barrier coatings, produced using the new Bluewave technology developed in partnership with Dow Chemical.

For aluminium lidding foils, a fully water-based combi-lacquer dispersion, based on chlorine-free, high molecular weight thermoplastics, offers excellent sealability to both PE and PS. Targeted at the dairy sector, its seal and peelability performance is combined with the necessary resistance to water, fat and lactic acid. For thinner heatseal foils, for applications such as soup cubes, processed cheese and chocolate wraps, Paramelt has developed a range of aqueous, ethylene copolymer emulsions said to provide excellent adhesion to aluminium combined with good lay-down, film formation, flexibility and crease resistance. “Superb barrier characteristics” and tailored minimum sealing temperatures are promised from a range of alternatives to the use of plasticised vinyl systems.

New from Wacker is a dispersion for formulating adhesives used in high performance paper and packaging applications, such as food bags and folding boxes for exclusive consumer goods. Vinyl acetate-ethylene (VAE)-based Vinnapas EP 8010 is said to bond challenging paper and board surfaces and film “reliably and permanently”. Also claimed is outstanding heat resistance, a very high setting speed and ease of machine processing. The new product is also manufactured without the use of alkylphenol ethoxylates, and its VAE basis makes supplementary plasticisers unnecessary, keeping the migration potential extremely low.

When Bobst recently ran trials with different suppliers of water-based products to find the best precision adhesive for folding carton conversion, HB Fuller came out top and is now working with the machinery group on a longer term basis.

The trials used both wheel and nozzle-based adhesive applicators. For the wheel-based method, HB Fuller’s Swifttak 5490 effectively supported machine speeds of 700m/min, with the absolute minimum of splashing and no skin build-up in the pot. Operational machine time was increased, and downtime and associated cleaning and waste reduced.

Smooth performance

Swifttak 5580, used for the nozzle applications, demonstrated high levels of flexibility through its “optimal compromise between long open time and fast setting”. It provided a secure adhesion and, as a clean running adhesive with a minimum of tailing, the trials highlighted the absence of glue build-up around the nozzle head and no spraying. Pierre Malherbe, Bobst service support director, folder-gluer line, comments: “Getting adhesives to perform at 700m/min is certainly a challenge. During the trial period, Swifttak 5490 worked smoothly with the absolute minimum of splashing, and our team was really impressed with how well 5580 performed.”

A focus for Collano is the development of ecologically beneficial solvent-free adhesives for label, tape and packaging applications. New waterborne systems have been developed for applications such as ultra-removable paper labels, alkali-washable paper labels for beer and wine bottles, high performance labels and tapes with well balanced adhesion and cohesion properties, suitable for different carriers, including PVC and foams. An even higher ecological benefit is provided by rubber-based and UV-curable acrylic hot melts with 100% solid content. Collano has also developed new adhesives for hot melt coating and printing applications.

Technology manager hot melt, Wolfgang Aufmuth, says: “UV curable pressure-sensitive hot melt adhesives have been used for label, tape and self-adhesive insulation materials for several years. Although there is only a limited range of cross-linkable raw materials available, formulation of these has opened a wide range of new adhesives. Adhesive formulation is needed to tailor a product to specific application or requirement. Besides conventional formulation with non-reactive tackyfier resins, we discovered additional routes. Compounding with UV-reactive additives enhances viscosity and adhesion properties. The additives also reduce the melt viscosity significantly and make the products suitable for direct coating of temperature-sensitive materials like PE. This adds another dimension to satisfy market needs with UV-curable pressure-sensitive adhesives.”

Beardow Adams has a hot melt adhesive said to combine “unrivalled versatility with outstanding performance”. Nick Beardow, sales and marketing director, explains: “BAMFutura 51 is unlike any other packaging adhesive. It’s been developed to bond strongly to a wide range of packaging materials, from PP, PET and varnish coated board to metallised polyester. Where manufacturers may have previously used several different adhesives, they can now replace these with BAMFutura 51, freeing up storage space while saving time and money. Also easy-to-handle, low odour and fume-free, it improves the working environment and provides a strong and reliable adhesive that will not taint foodstuffs and other perishable products.”

BAMFutura 51 has been formulated to offer exceptional thermal stability. It can be used “with confidence” from -40°C to +90°C and its viscosity changed by less than 1% when subjected to 7-day 160°C trials.

DuPont, supplier of “the world’s broadest range” of specialised co-extrudable adhesive resins, offers the Tie Resin Selector as the first step in selecting the best resin. The online predictive modelling tool promises to simplify a critical step in multilayer packaging design. Users start by identifying two materials to be joined together and the selector recommends grades of DuPont tie resins grouped by type of extrusion process.

Testing the setting speed of Wacker’s Vinnapas EP 8010 Wacker

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