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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.

ELASTOSIL® LR 5040


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.

Processing


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
2018 Polyurethanes Technical Conference
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