EP1141167A1 - Elektrisch isolierende Flüssigkeit - Google Patents

Elektrisch isolierende Flüssigkeit

Info

Publication number
EP1141167A1
EP1141167A1 EP99965203A EP99965203A EP1141167A1 EP 1141167 A1 EP1141167 A1 EP 1141167A1 EP 99965203 A EP99965203 A EP 99965203A EP 99965203 A EP99965203 A EP 99965203A EP 1141167 A1 EP1141167 A1 EP 1141167A1
Authority
EP
European Patent Office
Prior art keywords
ester
electrical insulating
carbon atoms
acid
insulating fluid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99965203A
Other languages
English (en)
French (fr)
Other versions
EP1141167A4 (de
Inventor
Jonathan Simon Hill
William David Phillips
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Lanxess Switzerland GmbH
Original Assignee
Great Lakes Chemical Europe GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Great Lakes Chemical Europe GmbH filed Critical Great Lakes Chemical Europe GmbH
Publication of EP1141167A1 publication Critical patent/EP1141167A1/de
Publication of EP1141167A4 publication Critical patent/EP1141167A4/de
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M105/00—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound
    • C10M105/08—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound containing oxygen
    • C10M105/32—Esters
    • C10M105/34—Esters of monocarboxylic acids
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
    • C10M2207/28—Esters
    • C10M2207/281—Esters of (cyclo)aliphatic monocarboxylic acids
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
    • C10M2207/28—Esters
    • C10M2207/282—Esters of (cyclo)aliphatic oolycarboxylic acids
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
    • C10M2207/28—Esters
    • C10M2207/283—Esters of polyhydroxy compounds
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
    • C10M2207/28—Esters
    • C10M2207/286—Esters of polymerised unsaturated acids
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/14—Electric or magnetic purposes
    • C10N2040/16—Dielectric; Insulating oil or insulators
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/14—Electric or magnetic purposes
    • C10N2040/17—Electric or magnetic purposes for electric contacts

Definitions

  • This invention relates to electrical insulating fluids, more especially to such fluids for use in transformers (particularly railway traction transformers), and most especially to such fluids that have excellent very low temperature performance.
  • the liquid filling in a transformer serves two important functions. It acts as a coolant and also as an insulant, and must possess the characteristics necessary to provide good performance in both these aspects, across the range of operational conditions the transformer will experience. It is also critical that the fluid should have good electrical properties. Due to the possibility of leaks, the environmental behaviour of such fluids is of increasing concern, and as a result, biodegradability and low toxicity are highly desirable in such fluids. Carboxylate esters are generally superior to hydrocarbons and silicones in this regard.
  • Transformers used in railway locomotives which experience very cold weather conditions require excellent low temperature properties.
  • a kerosene-base product has been used in the past.
  • the flash point of kerosene is only 95°C, and the fire point is 105°C, and this presents a fire hazard since the windings in the transformer can reach 120°C.
  • Carboxylate esters typically have much higher flash points than mineral oils. However, commercially available esters do not have sufficiently good low temperature properties. For example, di(2-ethylhexyl) adipate has a viscosity of 4920cSt at -54"C, di(2-ethylhexyl) phthalate has a viscosity of 1300cSt even at -10°C and a pour point of -30°C and dibutyl sebacate has a pour point at -15°C. Polyol esters (such as those based on pentaerythritol) commonly used in transformers have much too high viscosities at low temperatures (e.g. 24,000cSt at -40°C).
  • FR 2282467 describes a dielectric liquid composition for condensers and transformers based on 2-ethyLhexyl 2-ethylhexanoate (all or in part).
  • a mixture of the ester with chlorobiphenyls is disclosed.
  • the ester is claimed to be particularly superior (e.g. compared to dioctyl phthalate) in terms of thermal and chemical stability.
  • pour point is measured at -70°C, low temperature viscosity is not given. Having a total of only 16 carbon atoms, this ester will have flammability characteristics that are only borderline, and would not give a sufficient safety margin in the operation of transformers (literature flash point of only 132°C).
  • the present invention relates to the use of as an electrical insulating fluid certain monobasic carboxylate esters that have excellent low temperature properties, but also have improved flammability when compared to similar viscosity mineral oil.
  • flash points of at least 135°C and a fire point of at least 145 D C For a new insulant to be considered as a significant advance on existing materials, the industry expects a flash point of at least 15°C greater than the temperature reachable by the windings.
  • the esters have a viscosity ⁇ 1200cSt at -50°C, preferably ⁇ 800cSt and most preferably ⁇ 400cSt at -50°C. Additionally, the esters have a pour point of ⁇ -30°C, preferably ⁇ -40 C and most preferably ⁇ -50°C.
  • a balance has to be achieved between improving the fire safety of a fluid by having as high a flash point and fire point as possible, whilst retaining an acceptable viscosity at very low temperatures.
  • esters are suitable to meet these requirements.
  • the range is defined by the total number of carbon atoms in the ester molecule. Esters with up to 16 carbon atoms will not have sufficient fire resistance. Esters of more than 20 carbon atoms will have too high a viscosity at very low temperatures.
  • the present invention relates to the use of as an electrical insulating fluid, esters containing a total number of carbon atoms of from 17 to 20.
  • the molecular structural design will also critically influence performance. The most important of these are described as follows. Firstly, there has to be some degree of branching within the molecule, particularly in order to achieve the desired excellent low temperature properties. Secondly, both the amount and position of the branching can affect the properties of the resultant esters. It is impossible to predict accurately the precise effect of branching on key properties, but some general guidelines can be established: -
  • Branching can be on the alcohol or acid moiety or both.
  • Empirical observations show that the amount of branching should be from 10 to 50%, wherein the percentage is calculated as number of branched carbon atoms/total number of carbon atoms x 100%.
  • Monobasic carboxylate esters are prepared from the reaction of an alcohol and an acid. To retain good oxidative stability, a further limitation is that the esters must contain no unsaturation, i.e. both the acid and alcohol starting materials must be fully saturated. In order to achieve an ester with a total carbon number of 17 to 20, a number of different combinations of acid and alcohol are theoretically possible. For optimum performance (electrical and low temperature) it is preferred to have the ester functionality near the centre of the molecule. Moreover, for a given molecular weight ester, flammability tends to decrease with increasing number of carbons in the alcohol moiety.
  • esters suitable is the choice of alcohols containing from 6 to 13 carbon atoms, preferably 8 to 10 carbon atoms, and choice of acids containing from 6 to 13 carbon atoms, preferably 8 to 10 carbon atoms, but giving a total of 17 to 20 carbon atoms in the esters.
  • alcohols include synthetic materials (e.g. derived from the OXO process). Examples include 2-ethylhexanol, isooctanol, 3,5,5-trimethylhexanol, isodecanol and tridecanol and also mixtures eg mixed Cl 1/C13 alcohol. Alternatively, linear naturally- derived alcohols can also be used such as n-octanol, n-decanol and n-dodecanol and also mixtures eg LorolTM C8-C 10 Special (from Henkel).
  • acids may be synthetic in origin, for example C7, 8, 9, 10, 11, 12, 13 CekanoicTM acids (from Exxon) and mixtures thereof, and also n-heptanoic acid and 2-ethylhexanoic acid, Linear naturally derived acids are also suitable, for example capiylic acid, pelargonic acid, capric acid and lauric acid; in addition, mixtures eg EdenorTM V85 (C8/C10 fatty acid) (from Henkel).
  • the flash and fire points of a carboxylate ester may be dramatically affected by volatile impurities, such as residual alcohol raw material left over from manufacture (especially for lower molecular weight alcohols). It is important that such impurities are minimised to limit adverse impact on the flash and fire points.
  • an important aspect of the present invention is that the ester can have no more than 500ppm alcohol impurities, preferably no more than 200ppm and most preferably no more than lOOppm.
  • the resulting fluid may be made up of predominantly a single ester, mixtures of esters, or a mixed product made up by using isomeric raw materials (acids and/or alcohols).
  • an electrical fluid should have sufficiently high electric strength, low dielectric dissipation factor, high specific heat and thermal conductivity, low coefficient of thermal expansion, excellent chemical stability, low density; good lubricity, low solvent power; good arc-quenching properties and also be non- toxic and preferably also biodegradable.
  • electric strength should be at lest 40kV, preferably at least 50kV and most preferably at least 60k V.
  • Dissipation factor (tan ⁇ at 20°C) should be less than 0.1 and preferably less than 0.05.
  • the acid value of the ester should be less than 0.05mg gKOH and preferably less than 0.03mg gKOH.
  • ester be stabilised against oxidation.
  • a suitable additive package that can be optimised by those skilled in the art.
  • this might include an antioxidant (eg a hindered phenol such as bisphenol F (Ethyl 702). 2,6-di-t-butyl-p-cresol (DBC) and Benzenepropanoic acid, 3,5-bis (1,1- dimethylethyl)-4-hydroxy-,l,6-hexanediyl ester (Irganox 259)) and a metal passivator (eg a benzotriazole or a derivative thereof).
  • an antioxidant eg a hindered phenol such as bisphenol F (Ethyl 702). 2,6-di-t-butyl-p-cresol (DBC) and Benzenepropanoic acid, 3,5-bis (1,1- dimethylethyl)-4-hydroxy-,l,6-hexanediyl ester (Irganox 259)
  • the resulting fluid can also be used in related applications, for example, in traction transformers and especially in distribution transformers e.g. pole- mounted transformers.
  • esters of the invention may be made any of the standard methods that are well-known in the chemical industry, most easily by the direct reaction of the acid with the alcohol (though an acid chloride may be used as a more reactive alternative to the acid) with an appropriate catalyst.
  • an acid chloride may be used as a more reactive alternative to the acid
  • an appropriate catalyst for more detailed information refer to: Kirk-Othmer's Encyclopaedia of Chemical Technology 4th Edition, Volume 9, pp 755-780 or in Advanced Organic Chemistry by J March, pp 348-351 and references contained therein.
  • Catalysts for the direct reaction can be inorganic acids, for example sulphuric acid, hydrochloric acid, phosphoric acid, phosphorous acid, hypophosphorous acid, phosphotungstic acid, boron trichloride etc; or organic acids eg p-tolue ⁇ ) e sulphonic acid, methane sulphonic acid, trifltc acid; or organometallic compounds, eg dibutyl tin oxide or tetrabutyl titanate; or heterogeneous acid catalysts such as cationic ion exchange resins, NafionTM resin, or supported heteropolyacids.
  • inorganic acids for example sulphuric acid, hydrochloric acid, phosphoric acid, phosphorous acid, hypophosphorous acid, phosphotungstic acid, boron trichloride etc; or organic acids eg p-tolue ⁇ ) e sulphonic acid, methane sulphonic acid, trifl
  • Examples 1 to 9 (with no stabiliser) were prepared by a standard method (analysis given in Table 1) and evaluated for extreme low temperature performance and flammability. The results are described in Table 2.
  • Example 3 shows good electrical properties.
  • Example 5 is less good and demonstrates the importance of removing residual alcohol impurities.
  • n-octyl n-decyl 2-ethyl hexanoate also gave good results.
  • Example 8 The ester of Example 8 containing 0.5% by wt. of the stabiliser 2,6,2' _6'-tetra-t-butyl bisphenol F and 0.01% by wt. of the metal passivator benzotriazole was tested for electrical performance under IEC 247 conditions at 90°C and exhibited a Permittivity of 3 and Volume Resistivity of 14 which shows that the V.R. of the ester is not adversely affected by the inclusion of the stabilisers.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Emergency Medicine (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Chemistry (AREA)
  • Organic Insulating Materials (AREA)
  • Lubricants (AREA)
EP99965203A 1998-12-11 1999-12-10 Elektrisch isolierende Flüssigkeit Withdrawn EP1141167A4 (de)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GBGB9827207.3A GB9827207D0 (en) 1998-12-11 1998-12-11 Electrical insulating fluid
GB9827207 1998-12-11
PCT/US1999/029265 WO2000034409A1 (en) 1998-12-11 1999-12-10 Electrical insulating fluid

Publications (2)

Publication Number Publication Date
EP1141167A1 true EP1141167A1 (de) 2001-10-10
EP1141167A4 EP1141167A4 (de) 2002-06-26

Family

ID=10843991

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99965203A Withdrawn EP1141167A4 (de) 1998-12-11 1999-12-10 Elektrisch isolierende Flüssigkeit

Country Status (6)

Country Link
EP (1) EP1141167A4 (de)
AU (1) AU3117100A (de)
CA (1) CA2354700A1 (de)
GB (1) GB9827207D0 (de)
RU (1) RU2001119267A (de)
WO (1) WO2000034409A1 (de)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10208269B2 (en) * 2013-12-23 2019-02-19 Exxonmobil Research And Engineering Company Low viscosity ester lubricant and method for using
EP3429046A1 (de) * 2017-07-14 2019-01-16 Siemens Aktiengesellschaft Elektronischer schalter mit überspannungsbegrenzer
JP7176493B2 (ja) * 2019-08-26 2022-11-22 トヨタ自動車株式会社 冷却液組成物及び冷却システム

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3740625A (en) * 1971-11-04 1973-06-19 Sprague Electric Co Electrical capacitors with ester impregnants
DE2326225A1 (de) * 1972-06-28 1974-01-10 Exxon Research Engineering Co Verfahren zur reinigung organischer ester von chemisch wirksamen und elektrisch leitenden verunreinigungen und die verwendung der gereinigten ester als elektrische isoliermaterialien
FR2282467A1 (fr) * 1974-08-22 1976-03-19 Rhone Poulenc Ind Nouveaux liquides dielectriques
GB2110234A (en) * 1981-09-16 1983-06-15 Ciba Geigy Ag Dielectric fluid containing electrical devices
US4519932A (en) * 1982-09-20 1985-05-28 National Distillers And Chemical Corporation Low temperature hydraulic fluids based on two centistoke synthetic hydrocarbons
GB9210578D0 (en) * 1992-05-18 1992-07-01 Exxon Chemical Patents Inc Functional fluid
US5322633A (en) * 1992-11-16 1994-06-21 Albemarle Corporation Preparation of branched chain carboxylic esters
US5766517A (en) * 1995-12-21 1998-06-16 Cooper Industries, Inc. Dielectric fluid for use in power distribution equipment
US5949017A (en) * 1996-06-18 1999-09-07 Abb Power T&D Company Inc. Electrical transformers containing electrical insulation fluids comprising high oleic acid oil compositions

Also Published As

Publication number Publication date
GB9827207D0 (en) 1999-02-03
EP1141167A4 (de) 2002-06-26
CA2354700A1 (en) 2000-06-15
WO2000034409A1 (en) 2000-06-15
RU2001119267A (ru) 2003-06-27
AU3117100A (en) 2000-06-26

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