Momentive Announces A New Product Family Of Fully Fluorinated Silicone Liquid Elastomers (FFSL)

Germany - Momentive Performance Materials, a leading manufacturer of custom heat-cured elastomers (HCEs), liquid silicone rubber (LSR) and RTV specialty adhesives, introduces a new product family of Fully Fluorinated Silicone Liquid elastomers (FFSLs).

The new FFSLs combine the physical and chemical properties of standard fluorosilicone HCEs (including low and high temperature resistance, constant behavior over a broad temperature range) with the unique processing and productivity advantages of an addition-cured, platinum-catalyzed LSR (high cure speed, flash-less, trim-free, fully automated injection molding).

The Momentive FFSLs offer fuel resistance capabilities comparable to conventional fluorosilicone HCE. Besides suitability for Diesel/RME and hot oils as previous generation of fluorinated LSR (FSL), this new product family brings a full set of chemical resistance that is comparable to peroxide curable Fluorosilicone Heat Cured rubbers (FVMQ).

Fluorosilicones are broadly used in automotive applications where excellent low temperature flexibility in combination with exposure to fuels, oils, blow-by-gas, or hot air is required.

Additionally, Momentive has also developed the first oil-bleeding fluorosilicone within the new FFSL family. Typical applications are for wire harnesses and electrical connectors in potential contact with above critical media. This oil, bleeding out of the molded parts reduces forces for assembly and disassembly of cables and metal clamps, and helps to protect the seals from potential damage.

The family of FFSLs is being launched with products ranging in hardness from 40 to 70 Shore A. "We are targeting the automotive mass production applications in contact with fuels, oils or blow-by-gas," says Oliver Franssen, Industry Manager, Automotive Elastomers, Momentive Performance Materials. "Therefore, we need a family of products, such as 40 Shore A oil bleeding FFSL for connectors, a 70 Shore A product for O-Rings and 50 to 60 Shore products for Membranes, Seals and Gaskets. Within those application area's, the FFSLs should demonstrate cost efficiency through their productivity gain and at the same time will help increase the engineers' design freedom for multi-component parts. It is one of the biggest innovations in the high-performance elastomer arena in the last few decades."

At the 172nd Technical Meeting of the American Chemical Society's Rubber Division on October 16, 2007, Momentive presented a technical paper describing the advanced new FFSLs and comparing the new family of FFSLs with silicone heat-cured elastomers (HCEs) that contain fluorosilicone. "Over the last several years, the industry trend has been away from HCEs, in favor of the increased use of liquid silicone rubber (LSR) for molded rubber parts, due to easier processability, design versatility, quality and productivity gains offered by LSR." said ACS presenter Gail Riley, regional marketing manager, Momentive. "However, combining fuel and solvent resistance with high fluorine content for the most demanding applications has been a challenge. Our new generation of FFSLs represents a significant breakthrough, combining fuel and solvent resistance with higher fluorine content for use in very harsh environments."

A global team of up to 14 Momentive experts spent the last two years developing the FFSLs. "While we discussed the possibility of such a fully fluorinated LSR material over the last 10 years, it was the combination of three new ideas which brought us together in this team", says Dr. Stephan Bosshammer, Technology Leader for LSRs, Momentive Performance Materials. "We started this development with a white piece of paper. The big fluoro-containing side groups of the polymer chain made it very complex to design a low viscosity material. We benefited from our technology leading position in LSRs globally and our full backward integration as a supplier of Fluorosilicone Heat Cured rubbers. Our biggest and most critical achievements are: a viscosity comparable to our LSR standard grades and the availability of high hardness up to 70 Shore A."

Momentive worked with validation-customers, who gave input on physical properties and helped in the processing validation. "It is especially important in the automotive segment to work hand in hand with OEMs and Tier One companies to identify new product needs and to include our direct customers in highly confidential product developments," explains Franssen. "Production trials have been carried out on different machines with different mass-production molds and cold runners with up to 64 cavities in a fully automated process. Processing of the new FFSL material is comparable to standard LSR grades. In parallel, we spent months of lab-testing to prove the chemical resistance of FFSL in relation to existing commercial fluorosilicones."

The new Momentive FFSLs will be available as of November 2007. Momentive will offer support through a focused automotive development and marketing organization, which also will handle the relevant industry network of equipment suppliers, mold manufacturers as well as to the automotive system suppliers and OEMs. Joint validation trials can be carried out in the local Momentive ADCs (Application Development Centers).

SOURCE: Momentive Performance Materials