Coffee cup lid made of liquid silicone rubber

Reuse Beats Single Use

ELASTOSIL® LR 5040 from WACKER is a liquid silicone rubber that meets the requirements imposed on food-contact materials – without the need for thermal postcuring. It should help contain the growing mountain of disposable coffee-cup lids.

May 19, 2020 Read time: approx. MinutesMinute

Reuse Beats Single Use

A staggering 2.8 billion disposable coffee cups change hands in Germany’s cafés, bakeries and coffee shops every year, and are then tossed away when empty. On average, that is the equivalent of 34 cups per year for every German. A lot of lids are used, too – some 1.3 billion of them. In an effort to reverse this waste of resources and to minimize the environmental impact, the German Environment Agency is now actively encouraging multi-use systems for coffee cups, and is targeting a 50-percent reduction in consumption of disposable cups within the next three years. Environmental Action Germany (DUW) has calculated that a reusable coffee cup would only have to be used ten times to offset the greater outlay involved in its manufacture, relative to that for the disposable product.

“Recup” coffee-to-go cup with a WACKER LSR lid produced on a Kraus-Maffei injection-molding machine

Easy to grip and dishwafer-safe, while ensuring effective sealing: reusable coffee cup lids made of silicone.

WACKER’s new ELASTOSIL® LR 5040 series of liquid silicone rubbers could go some way toward meeting this goal. Liquid silicone rubber (LSR) has the key advantage of allowing silicone rubber articles to be mass-produced quickly, efficiently, cost-effectively and with great accuracy in a highly automated injection-molding process. As silicone articles for baby care, foodstuffs and medical technology have to meet special regulatory requirements, they have to be heated after production if they have been made from conventional LSR. This process step is commonly known as postcuring. It entails heating the material in a fast-moving stream of air in an oven at 200 degrees Celsius for a protracted period. This drives off the volatile organic components and optimizes the mechanical properties of the end product.

“With ELASTOSIL® LR 5040 series liquid silicone rubbers, this expensive, time-consuming and labor-intensive step can be eliminated in almost all cases. What’s more, quality assurance improves because the intermediate step always involves a risk of contamination. Not only that, but postcuring takes several hours and so a great deal of energy can be saved by eliminating it.”

Dagmar Rische, Marketing Manager for Healthcare Products, WACKER SILICONES

Live Demonstration

The non-postcuring liquid silicone rubbers in the ELASTOSIL® LR 5040 series were unveiled at K 2019, the world’s foremost plastics and rubber tradeshow, held in the fall of last year. A particularly impressive feature at the WACKER booth was the live injection-molding demonstration run in conjunction with partners KraussMaffei Technologies GmbH, ACH Solution GmbH and AVR Tech Innovations GmbH. Drums containing the A and B components of the liquid silicone were attached to the metering unit at one end of an injection-molding machine, while a steady stream of finished products came out the other end – silicone lids that visitors were invited to put on their reusable coffee cups straight away. “Guests came away from our booth with a hands-on product that they could use immediately,” reports Rische. “The demonstration production line was a great way for us to showcase the material’s impressive potential.” The demonstration line was a collaboration between machine-maker KraussMaffei Technologies and ACH Solution GmbH, a specialist in tool-making and automation technology. “The transition from postcuring silicone to non-postcuring liquid silicone rubber went without a hitch,” says Robert Köttner, head of sales and material development at ACH Solution. This sentiment is shared by Cordula Wieland, product and technology manager at KraussMaffei. It came as a bit of a surprise, she explains, adding:

“Behind products such as baby pacifiers and coffee cup lids, which are a particularly sensitive area because they involve contact with the mouth and saliva, there is a tightly regulated process that seeks to ensure a high level of safety.”

Cordula Wieland, product and technology manager at KraussMaffei

Coffee cup lids made of liquid silicone rubber are injection-molded on this equipment in a wholly automated process.

A further benefit, she notes, is that the products can be tracked more easily throughout the process, whereas in the postcuring process variant the flow is interrupted.

Lids for reusable cups are one of many possible applications for liquid silicone in the food sector. “ELASTOSIL® LR 5040 is WACKER SILICONES’ response to customer wishes,” says Dr. Ulrich Frenzel, a chemist who provides technical support for the Rubber Solutions team at WACKER SILICONES. “The material is ultimately designed to meet the strict regulatory requirements encountered in numerous sensitive approval areas, whether these be the pharmaceutical sector, medical technology, or applications involving contact with drinking water or food.”

Silicone rubber also easily withstands UV, heat and steam, allowing reusable lids made from this material to be cleaned in industrial dishwashers. “It is thus ideal for the recycling systems sought after by the hospitality sector,” adds Rische. And silicone rubber can be pigmented in any color. For lifestyle accessories such as cappuccino and latte macchiato cups, that is an added extra which is not to be sniffed at.

WACKER’s K 2019 tradeshow booth

Together with partners KraussMaffei Technologies GmbH, ACH Solution GmbH and AVR Tech Innovations GmbH, WACKER demonstrated the injection-molding of liquid silicone rubbers at the K 2019 plastics tradeshow in Düsseldorf.

ELASTOSIL® LR liquid silicone rubber (LSR) products are platinum-catalyzed, addition-curing, two-part silicone rubber grades which can be injection-molded on fully automated equipment, usually without the need for secondary processing. They are ideal for high-volume manufacturing, support short cycle times and so help to keep unit costs down. Injection molding supports complex part geometries and narrow dimensional tolerances.

Mrs. Dagmar Rische
Marketing Manager
+49 89 6279-1332