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The Packaging Makes All the Difference

At supermarket shelves, the packaging is often what determines what goes in customers' shopping carts. WACKER has now developed VINNAPAS® EP 8010, a new dispersion for formulating sophisticated paper and packaging adhesives that also prevent unwanted substances from migrating into food.

Packaging does much more than simply protect products during shipping. Indeed, packaging is often what lends a product the individuality promised by its advertising. When supermarket customers are confronted with three dozen types of breakfast cereals, making a decision is frequently difficult – and the packaging is often what prompts the customer to make a purchase. The German Packaging Institute (Deutsches Verpackungsinstitut) estimates that consumers make two-thirds of their purchase decisions at the point of sale, i.e., not until they are standing immediately in front of supermarket shelves. Among the cheerful array of products on display, the packaging is what delivers the actual sales pitch. Knowing this makes industry players all the more eager to use the outward appearance of their products as a way of distinguishing themselves from the competition. According to a PricewaterhouseCooper study, material innovations constituted the second most important topic for packaging manufacturers after energy consumption. For 72 percent of all packaging material producers, this represents a major challenge.

At WACKER’s applications laboratory, Angelika Ellbrunner tests the setting speed of paper and packaging adhesives based on VAE copolymers.

Yet no matter how much they may crave innovative materials, one principle always applies: substances potentially posing health hazards must never migrate from packaging into food, and packaging must never cause organoleptic changes to food, i.e., it must not alter the aroma or taste. “This impacts all of the materials used in food packaging,” says Dr. Gerhard Kögler, the platform manager for Technical Services Adhesives Europe at WACKER, “and not just its primary components, such as paper, cardboard and plastic. Printing inks and adhesives are affected too, for instance.” This poses a special challenge to packaging manufacturers and food producers, who must understand the migration behavior of all of the substances used in packaging – taking interactions into consideration as well – in order to rule out any negative impact on the packaged product. Given the wide variety of potential combinations, achieving this goal requires exceptional effort.

The safer and easier solution is to use materials in which migration is minimal or non-existent. While printing inks and finishes are a particular focus here, the adhesives that hold many packaging materials together also receive special attention. Adhesives often may contain additives of low molecular weight such as plasticizers and tackifiers that make them easier to process and allow them to adhere well to the substrates to be bonded. Each of these groups of substances typically tends to migrate somewhat, raising the possibility of unwanted materials – or even potentially unhealthy materials – finding their way into packaged foods. Adhesives based on vinyl acetate-ethylene (VAE) copolymers, by contrast, leach very few substances into food. WACKER expert Gerhard Kögler explains the reason: “Due to the composition of vinyl acetate-ethylene copolymers, the polymer chains are themselves flexible enough that we can dispense with the use of plasticizers and film-forming agents when formulating adhesives. Our copolymers are easy to process, and the ethylene groups in the polymer chain ensure that a film forms without the use of plasticizers, thus generating a secure bond with the substrate.”

“The ethylene groups in the polymer chain ensure that a film forms without the use of plasticizers.”

Dr. Gerhard Kögler, Technical Service Adhesives, WACKER POLYMERS

Challenging Plastic Surfaces

In order to spark consumer interest, consumer goods are trending increasingly toward high-quality packaging. A wide variety of different materials are used in the types of packaging that consumers find particularly attractive, and these materials place special demands on the adhesives used – this is where traditional VAE dispersions quickly reach their limits. In an effort to meet the challenges posed by this development, WACKER has developed a new vinyl acetate-ethylene copolymer dispersion that reliably bonds plastic films to sophisticated paper and cardboard surfaces: VINNAPAS® EP 8010 shows excellent adhesion to a wide range of difficult-to-bond substrates such as polystyrene, polyester or lacquered surfaces.

In addition to excellent adhesion, the properties of this new product also include resistance to temperatures of well over 100 °C under normal conditions and a setting speed that is quite fast for packaging applications. This balance of outstanding adhesion combined with extremely good heat resistance makes VINNAPAS® EP 8010 well-suited to a very broad range of applications. VINNAPAS® EP 8010 works especially well for creating sophisticated packaging, where it acts essentially as an all-round adhesive. “Being able to see a product directly is often an important aspect of today’s packaging designs,” says Sung Shin Moon, global market manager at WACKER. “Consumers want to see – and should see – what they’re buying, especially when it comes to food.” VINNAPAS® EP 8010 allows manufacturers to work with packaging innovations that many find to be especially challenging, yet, at the same time, it also meets the needs of end consumers and industry alike: products are kept safe and fresh, yet protected from undesirable changes.

Uses for VINNAPAS® EP 8010 are not limited to the paper and packaging industries, however. Surfaces that are difficult to bond represent a challenge in other applications as well, such as lamination for the automotive industry. The unique properties of VINNAPAS® EP 8010 (especially its superior adhesion balanced with considerable heat resistance) open up countless new applications that adhesive manufacturers are now slowly but surely exploring.

New Method For Measuring The Setting Speed

WACKER has gone to great lengths to verify the fast setting speeds and excellent adhesion of VINNAPAS® EP 8010. To this end, the company’s application technology team has developed a precise new method for determining the setting speed:

Step 1:

Affix a paper strip to a modified PTS instrument

Step 2:

Next, use a roll doctor to apply adhesive evenly onto the strip and place a second layer of paper on top of this to form a bond.

Step 3:

A rod is then pulled through the bonded substrates and the delamination force measured as a function of time.