Dielectric Fluid Compositions for Enhanced Thermal Management

摘要

A dielectric fluid composition for electrical apparatus comprises a functionalized 12-hydroxy stearic acid having desirable properties including a pour point less than −30° C. and a fire point greater than 250° C. It may be prepared by a process wherein 12-hydroxy methyl stearate is transesterified by reaction with a C3-C20 alcohol to form an alkyl-12-hydroxy stearate, followed by esterification thereof with a linear or branched C4-C20 carboxylic acid. This acid may be a free acid chloride, a fatty acid, a carboxylic acid anhydride, or combination thereof. The resulting functionalized 12-hydroxy stearic acid exhibits improved thermoxidative capability, low temperature flowability, and increased fire point.

主权项

1. A dielectric fluid composition for electrical apparatus
prepared by a process comprising (a) reacting 12-hydroxy methyl stearate and a linear or branched C3 to C20 alcohol under conditions suitable to form an alkyl-12-hydroxy stearate; and (b) reacting the alkyl-12-hydroxy stearate and a carboxylic acid selected from the group consisting of linear and branched C4-C20 free acid chlorides, fatty acids, carboxylic acid anhydrides, and combinations thereof; under conditions suitable to form a functionalized 12-hydroxy stearic acid having at least one property selected from the group consisting of: (a) a number average molecular weight from 400 Daltons to 10,000 Daltons; (b) a dielectric breakdown greater than 20 kilovolts/1 mm gap; (c) a dissipation factor less than 0.2 percent at 25° C.; (d) a fire point greater than 250° C.; (e) a kinematic viscosity less than 35 centistokes at 40° C.; (f) a pour point lower than −30° C.; (g) an acidity less than 0.03 mg KOH/g; and (h) a combination thereof.