Dielectric fluid compositions for enhanced thermal management

Patent metadata

Field	Value
Publication number	US-9793027-B2
Application number	US-201615156795-A
Country	US
Kind code	B2
Filing date	May 17, 2016
Priority date	Sep 30, 2011
Publication date	Oct 17, 2017
Grant date	Oct 17, 2017

Abstract

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.

First claim

What is claimed is:

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.

2. The dielectric fluid composition of claim 1 , wherein the functionalized 12-hydroxy stearic acid is present in an amount ranging from 1 weight percent to 100 weight percent.

3. The dielectric fluid composition of claim 1 , wherein the functionalized 12-hydroxy stearic acid is present in an amount ranging from 30 weight percent to 90 weight percent.

4. The dielectric fluid composition of claim 1 , further comprising a natural triglyceride; a genetically modified natural oil; a synthetic ester; a mineral oil; a poly alpha olefin; or a combination thereof.

5. The dielectric fluid composition of claim 1 , wherein the number average molecular weight is from 400 Daltons to 5,000 Daltons.

Assignees

• Dow Global Technologies Llc

Inventors

• Han Suh Joon
• Zinkweg Dirk B
• Lysenko Zenon

Classifications

• H01B3/20 Primary

  liquids, e.g. oils (silicone oils H01B3/46) · CPC title

• C07C51/367

  by introduction of functional groups containing oxygen only in singly bound form · CPC title

• C07C59/01

  Saturated compounds having only one carboxyl group and containing hydroxy or O-metal groups · CPC title

• H01B3/30

  plastics; resins; waxes · CPC title

• H01B3/24

  containing halogen in the molecules, e.g. halogenated oils · CPC title