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WACKER Showcases Non-Post Cure LSR for Baby Care, Food Contact & Medical Uses at Fakuma

Published on 2017-10-18. Author : SpecialChem

Non-Post Cure LSR
Non-Post Cure LSR
At this year’s Fakuma international tradeshow for plastics processing, the Munich-based chemical group WACKER is showcasing its new liquid silicone rubber line ELASTOSIL® LR 5040.
  • These grades feature excellent mechanical properties after curing even without thermal post-treatment. 
  • They contain only few volatile components making the liquid silicone rubber (LSR) compliant with regulatory specifications governing sensitive applications in baby-care, food-contact and medical sectors. 
  • In many cases, processors do not need to post-cure the silicone elastomers after vulcanization. 

Non-Post Cure LSR

Silicone parts intended for use in the baby-care sector and the food industry in Europe must contain no more than 0.5 percent volatile substances. To ensure compliance with this limit, thermal post-treatment is often necessary. That entails heating the cured parts to temperatures of 200 degrees Celsius for several hours in a ventilated oven. This process step, which specialists also refers to as “post-curing”, accomplishes two things: it eliminates volatiles from the elastomer and improves its mechanical properties.

This laborious and expensive procedure will soon be obsolete.


Christian Gimber, head of the Engineering Silicones business unit at WACKER, said:
“We designed ELASTOSIL® LR 5040 in such a way that this silicone rubber already complies with current regulatory requirements governing applications in the baby-care sector and food industry in its non-post cured state. Thus, in many cases, our customers can eliminate post-curing of silicone parts for sensitive applications.”

Key Properties

Rubber parts made of ELASTOSIL® LR 5040 are translucent with a delicate blue shimmer.
  • Their volatiles content – without thermal post-treatment – is below the required 0.5 weight percent. 
  • Even in its non-post cured state, the silicone rubber already exhibits a high level of tear resistance equivalent to that of a post-cured high-tear-strength standard LSR. 
  • As a result, it can withstand even high mechanical stresses as may occur during the usage of baby bottle nipples or pacifiers, for example. 

These properties make ELASTOSIL® LR 5040 the material of choice when manufacturers of baby-care, food-contact or medical products want to do without thermal post-treatment. Typical applications include feeding teats and pacifiers, teething rings, anti-colic valves, bottle tops and seals for food cans, but also respirator masks.


ELASTOSIL® LR 5040 can be readily processed by injection molding. Since molded parts made of this LSR only have to be post-cured in very few cases, production processes can be greatly streamlined and automated to a high degree. This facilitates very efficient and cost-effective large-scale production.

The product line will initially cover a hardness range from 30 to 70 Shore A including 45 Shore A, a universally used grade in the baby-care sector. In the cured state, the actual hardness of the non-post cured silicone rubber deviates by no more than ±3 points. The LSR is translucent and has a delicate blue shimmer, giving the silicone parts a particularly pure, high-quality appearance.

WACKER Optimizes LSR Product Portfolio

ELASTOSIL® LR 5040 made its debut at the K 2016 International Trade Fair for Plastics and Rubber in Düsseldorf, Germany, last October. At this year’s Fakuma, the product line again takes center stage, sharing the spotlight with the heat-resistant solid silicone rubber ELASTOSIL® R plus 4350/55.

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Source: WACKER
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