New Lube 0il for Stationary Air Conditioner

Replacing R-22 by HFC refrigerants in stationary air conditioners is forcing oil producers to develop a new lubricant which has good miscibility with HFC, lubricity and electric resistivity. Mitsui has selected a carbonate compound for a new lubricant candidate with HFC and developed it forcusing on its thermal stability, which is one of the most important factors to get good lubricity. By suppressing the hydrogen bond between 8-position H and a carbonate group, Mitsui has successfully synthesized the new carbonate type lubricant. This new carbonate type lubricant has good thermal stability, lubricity which is almost the same level as SUNISO 4GS, miscibility with SUVA AC-9000 and high electric resistivity and forms no acids by its decomposition. INTRODUCTION R-22 refrigerant which is used in stationary air conditioners is to be abolished completely by the year 2020. Replacement HFC refrigerants are not compatible with mineral oils and a new lubricant is required. This new lubricant must have a viscosity grade of about VG68, good miscibility with the new refrigerant, high electric resistivity, thermal stability and lubricity. Ester, ether and carbonate compounds have been evaluated. Ester type products have corrosion problems due to their tendency to form acids while ether type products demonstrate poor miscibility and electric resistivity. Carbonate types have good miscibility, electric resistivity and corrosion properties (don't form acids), but poor thermal stability and lubricity1) 2). This paper introduces a new carbonate oil for stationary air conditioners which shows singnificant improvements in thermal stability and lubricity. EXPERIMENTALS 1. Synthesis of Carbonate Various carbonates were synthesized by reacting dimetyl carbonate with alcohols under catalyst ( eq. 1). CHaOC02CHa + 2ROH ~ ROC02R + 2CH3 0H (eq.l) If necessary, carbonates obtained were modified.