Fomblin® PFPE Additives: Improving Thermal, Chemical, and Oxidative Resistance

Fomblin® perfluoropolyethers are a unique line of lubricants offering exceptional chemical  resistance, better subzero temperature properties, greater thermal and oxidative stability and lower evaporation loss than almost all other types of formulated lubricants. Though non-reactive themselves, due to their permeability to gases and vapors, Fomblin® PFPE fluids may not always provide adequate rust protection to metal surfaces. In these applications, often under extreme oxygen and humidity conditions it is desirable to enhance Fomblin® PFPE’s performance by a rust preventative additive.

Most of the commonly used lubricant additives are not soluble in perfluorinated lubricants and consequently, are impractical to use with Fomblin® PFPE. Based on proprietary technology, Solvay Specialty Polymers has developed a line of patented PFPE-soluble anti-rust additives. These new soluble additives termed “Fomblin® DA series”, are derived directly Fomblin® PFPE’s production process and contain functional groups, which can interact with the substrate and thereby improve surface protection.

Fomblin® DA305 is the optimum product for use with greases. Solutions of Fomblin® PFPE lubricants formulated with 5% (wt.) of DA305 are clear and stable in storage for over 1 year. These blends can be used in exactly the same manner as non-additivated Fomblin® lubricants for the production of greases. The physical properties of greases additivated with DA305 remain practically unchanged compared to those of the non-additivated greases; volatility may increase slightly, depending on the base fluid, and oil separation may decrease. Depending on the base fluid, these greases can be used at temperatures ranging –70 to 250°C.

Fomblin® DA306/VAC is primarily recommended for formulations with Fomblin® Y-LVAC fluids. Solutions of Fomblin® lubricants additivated with 5% (wt.) of DA306/ VAC are clear and stable in storage for over 1 year. It imparts anti-rust properties without significantly affecting the volatility and the viscosity of the original fluid, the typical physical properties remaining unchanged. The additive does not significantly affect either the ultimate pressure or the back-migration rate. Fluids additivated with DA306/VAC can be used at temperatures ranging –70 to 250°C.

Applications of additivated fluids and greases

The availability of additivated Fomblin® PFPE fluids widens the range of applications for perfluorinated fluids and greases in fields demanding high anti-rust properties.

These applications include lubrication of bearings, gears, turbine and liquid compressors that may be in contact with condensed water vapor. These additives also provide an opportunity to use Fomblin® PFPE as a hydraulic fluid, filling fluid and solvents where antirust prevention is one of the primary product specifications. Pretreatment with additivated Fomblin® Y-VAC fluids protects vacuum pumps during storage and transportation without affecting the performance of Fomblin® PFPE fluids (i.e. vapor pressure, chemical and thermal stability), thereby avoiding the need to clean the pump to remove the antirust protective agent.

Additionally, the additive protects the body of the pump in the presence of highly oxidizing agents. Additivated Galden® PFPE solvents can be easily applied to metal parts by spraying or coating. The residual film of the additive guarantees long term corrosion protection and is effective both in Fomblin® PFPE fluids and in greases. The treatment does not require long cleaning procedures to remove products not compatible with fluorinated materials. Metal parts can be treated with a thin highly protective anti-rust layer which is completely compatible with Fomblin® PFPE fluids and greases.