Tightly Sealed, Yet Easily Opened/ The best way to seal yogurt cups

Product Story No. 20

The lid of the yogurt cup pulls off cleanly and easily with an assuring rrrrip. The cup is bonded to the lid with a heat seal lacquer that keeps the contents fresh while ensuring that the lid peels off easily when required. Evonik has now made it possible to apply the lacquer to the lid in one single production step so that producers save time and costs and consumers keep their fingers clean.

Statistics show that the average European consumes almost 20 kilograms of yogurt a year, and the amount is increasing. This translates into 120 cups, every one of them opened by hand. Behind this apparently simple routine lies a vast amount of sophisticated technology. Consumers take for granted that packaged foods will be fresh; for developers of food packaging, this is nothing short of a formidable challenge. For yogurt cups, it means that the lid must adhere firmly enough to the plastic cup to protect the contents; on the other hand the lid must be easy enough to remove so that it doesn’t tear when the cup is opened.

Heat seal lacquer satisfy both of these requirements. Evonik’s specialty polymers play an important role here and are integral components of the sealing lacquers used. They ensure an ideal relationship between cup and lid, without either becoming overly attached to the other!

Close collaboration with customers
Producers of packaging coatings and sealing foils place high demands on binders. Good adhesion to a variety of lid materials such as aluminum and the plastic polyethylenterephalate foil (PET foil) is important, as is good sealability versus a very wide range of cup materials. It goes without saying that the material must also be safe for health and the environment. Yogurt cups are only one example of the applications of such binders; in the case blister packaging for tablets, the binders are responsible for sealing the aluminum foil to the plastic material.

Dairy products, particularly yogurt, are packaged and sold in polypropylene or polystyrene cups. When it comes to the shelf life of yogurt, aluminum is the preferred lid material. Lids of PET films metallized with aluminum are currently immensely popular because they reduce production costs while allowing a long shelf life.

A few numbers give an idea of the minute dimensions: The processed films are no more than 12 to 50 micrometers thick. A normal human hair, by contrast, is between 60 and 80 micrometers. A square meter of the film weighs less than 70 grams.

And that’s not all. The art lies in producing a secure, yet easily undoable bond between cup and lid. For this purpose, the lid is first coated with heat-seal lacquer and affixed to the cup. A heat sealing press then fuses the lacquer, sealing the yogurt cup securely.

Universally useable
Most packaging producers today use an additional base coat to enable the heat seal lacquer to adher to the PET lid and seal versus the plastic cup. With Evonik’s DEGALAN® VP 4174 E, they can dispense with the base coat because the product has direct-adhesion properties. The result is a more convenient production process that eliminates one production step. Testing was successful, and the product has already been supplied to the first customers.

Specialists in demand
In the give-and-take between packaging and food producers, Evonik’s specialty products offer major advantages. Thanks to lower resource consumption, overall costs and environmental pollution can be reduced.

Company information
Evonik Industries is the creative industrial group from Germany which operates in three business areas: Chemicals, Energy and Real Estate. Evonik is a global leader in specialty chemicals, an expert in power generation from hard coal and renewable energies, and one of the largest private residential real estate companies in Germany. Our strengths are creativity, specialization, continuous self-renewal, and reliability. Evonik is active in over 100 countries around the world. In its fiscal year 2008 about 41,000 employees generated sales of about €15.9 billion and an operating profit EBITDA of about €2.2 billion.

Alexandra Boy
Corporate Press
Phone +49 201 177-3167
Fax +49 201 177-3030
alexandra.boy@evonik.com

Text and images available to download at
www.evonik.com
May be reproduced free of charge, provided source is stated

Evonik Industries AG
Rellinghauser Strasse 1-11
45128 Essen
Germany
www.evonik.com

This release was published on openPR.