At Fakuma, the international trade fair for plastics processing, Wacker Chemie AG is presenting new silicone rubber grades that do not need to be post-cured after processing. ELASTOSIL® LR 5003 liquid silicone rubber is suitable for applications in the food industry and other sensitive areas and does not require post-curing to comply with regulatory limits. 

The chemical group is also presenting a novel solution for marking silicone rubber. ELASTOSIL® COLOR PASTES ensure that such silicones can be permanently and precisely labeled by laser. The spotlight is also trained on ELASTOSIL® eco. These silicone rubber grades are manufactured in a resource-efficient manner using non-fossil methanol. This year, Fakuma is taking place in Friedrichshafen, Germany, from October 17 to 21. 

Silicone rubber frequently undergoes post-curing after processing. During this post-curing procedure, the cured silicone elastomer is heated in a well-ventilated oven for several hours to temperatures of up to 200 degrees Celsius. This eliminates volatile components while enhancing the strength of the silicone rubber. However, this is an expensive step in production that not only consumes a lot of time and energy, but also interrupts the flow of a highly automated production process.

WACKER has now developed yet another line of non post-curing silicone rubber grades under the name ELASTOSIL® LR 5003, which is particularly suitable for the large-scale manufacture of products in the food industry and other sensitive areas. As far as their volatiles content is concerned, molded parts made from such silicones comply with the limits stipulated by the German Federal Institute for Risk Assessment (BfR) even without post-curing. They also meet the requirements of the U.S. Food and Drug Administration (FDA) for food contact products. This means that products such as reusable drinking straws, baking pans, dough scrapers and other items can now be produced very efficiently. ELASTOSIL® LR 5003 may be additionally post-cured in order to achieve even greater strengths and an even lower volatiles content.

ELASTOSIL® LR 5003 complements ELASTOSIL® LR 5040, which is also a non-post-curing liquid silicone rubber. Even without post-curing, the latter exhibits a high degree of tear resistance, a property required for, for example, drinking and soothing teats, teething rings, and other babycare articles that have to withstand high mechanical stresses.

New: Color Pastes for Marking Silicone Elastomers

In many application areas, for example, in the identification of cables or hoses in medical applications or for the tracking of production series and batches, the durable marking of silicones is desirable. However, marking using conventional printing methods is pushed to its limits when it comes to silicone elastomers. The labeling is often rubbed or blurred during marking.

WACKER has now solved this problem. With ELASTOSIL® COLOR PASTES Laser Marking, the group has developed a product that allows for the permanent labeling of silicone elastomers using lasers. The pastes contain laser-sensitive pigments which, when exposed to laser light at a wavelength of 1064 nanometers, very precisely either change their color or cause the elastomer to foam. This creates a permanent, non-washable mark inside or on the surface of the product. This marking is resistant to heat, sunlight, and UV light. Marking is contactless – either as a separate marking step after production or during the production process.

To enable the best possible legibility on silicone rubber of various colors, WACKER offers three easy-to-use masterbatches for laser marking on both liquid silicone and solid silicone rubber:

• ELASTOSIL® COLOR PASTE Laser Marking White – for white markings on dark substrates
• ELASTOSIL® COLOR PASTE Laser Marking Black – for black markings on light-colored substrates and
• ELASTOSIL® COLOR PASTE Laser Marking Black TRL – for black markings on transparent substrates.

ELASTOSIL® eco

In addition to ELASTOSIL® 5003 and ELASTOSIL® COLOR PASTE, ELASTOSIL® eco is also showcased at the booth. These are silicone rubber grades produced in a resource-efficient manner. They are manufactured in a certified process with the aid of methanol derived from plants rather than from fossil materials. ELASTOSIL® eco silicones are certified in accordance with the REDcert2 standard, which ensures the traceability of renewable raw materials along WACKER’s entire manufacturing process.

Visit WACKER at Fakuma 2023 in Hall A6, Booth 6212.