Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/20—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances liquids, e.g. oils
  • H01B3/22—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances liquids, e.g. oils hydrocarbons

Definitions

• This invention relates to synthetic oils useful for the insulation of electrical apparatus and more particularly it relates to the preparation and use in electrical power transformers of novel mono and dialkylates of an aromatic compound in which the alkylate portion is an oligomer of a four to 12 carbon alpha-olefin containing predominantly at least about 30 carbon atoms up to about 60 carbon atoms.
• a typical light mineral oil transformer fluid suitable for general transformer use has a fire point of about 160° to 165° C. (ASTM D92) and a flash point of about 145° to 150° C. (ASTM D92).
• Dimethyl silicone meets many of the requirements and is in current use, but it is nonbiodegradable and is considered to be much too expensive to capture a substantial portion of the requirements.
• U. S. Patent No. 4,082,866 several saturated. hydrocarbon oils are described which have a number of desirable properties for power transformer use. However, they are also significantly deficient in other properties.
• the paraffinic oil disclosed in this patent desirably possesses a high fire point but undesirably it also possesses a high viscosity and high pour point while the naphthenic oil described in this patent possesses a suitable viscosity but has a low fire point and a high pour point.
• the fire point as determined by ASTM D92 is a critical property of a fire-resistant transformer fluid.
• the fire point represents that temperature of the fluid at which sustained combustion occurs when exposed to the atmosphere. It is preferred that the fire point of a transformer fluid intended for general use be at least about 275° C. (527° F.) for reasonable safety against the various hazards inherent with low flammable fluids and more preferably should be at least about
• Viscosity is a measure of the resistance of a fluid to flow. At the lower viscosities a transformer fluid possesses better internal fluid circulation and better heat removal. But reducing the overall carbon number of an oil to reduce its viscosity also tends to significantly reduce its fire point. Conversely, in attempting to increase the fire point by using higher carbon number oils generally results in the use of significantly more viscous oils.
• the superior insulating fluid possesses a low viscosity at all temperatures over a useful range while maintaining adequate protection against flammability.
• the superior insulating fluid also possesses a high viscosity index. In particular, it exhibits a low viscosity at elevated temperatures, such as at 100° C. and higher in order to protect the transformer against the development of hot spots.
• An acceptable transformer fluid can possess a 98.9° C. (210° F.) viscosity as high as 20 cs. but it is preferred that a transformer fluid have a maximum 98.9° C. (210° F.) viscosity of about 15 cs. and that it have a viscosity index of at least about 110. It is most preferred that the transformer fluid have a maximum 98.9° C. (210° F.) viscosity of about 12 cs.
• Pour point is also significant in the overall usefulness of the transformer fluid, particularly with regard to starting equipment in cold climates.
• a maximum pour point of -25° F. (-31.7° C.) is considered to be essential while a maximum of about -40° C. (-40° F.) is preferred for the transformer fluid.
• Pour point depressants are well known but their use in transformer fluids is not favored because of the possibility that these materials may decompose in service with time. Also even with the use of a pour point depressant, it may not be possible to achieve the desired pour point. Therefore, it is desired that the unmodified transformer fluid have an acceptable pour point.
• the tendency of a transformer fluid to form gas as determined by ASTM D2300B is another characteristic which is important in some specifications.
• ASTM D2300B The tendency of a transformer fluid to form gas as determined by ASTM D2300B is another characteristic which is important in some specifications.
• a 10,000 volt a.c. current is applied to two closely spaced electrodes, one being immersed in the transformer fluid under a hydrogen atmosphere.
• the amount of pressure elevation is an index of the amount of decomposition resulting from the electrical stress that is applied to the liquid.
• a pressure decrease, indicated by a negative pressure reading is indicative of a liquid which is stable under the corona forces and which is a net absorber of hydrogen.
• a novel, synthetic transformer fluid can be prepared which meets the electrical and physical requirements in an exemplary manner and which possesses substantially lower flammability than conventional mineral oil transformer fluids and is environmentally safe.
• thisnovel transformer fluid can-be prepared, by reacting an aromatic compound with an oligomer fraction obtained by the oligomerization of an alpha-olefin or a mixture of two or more oligomer fractions.
• the alpha-olefin oligomer which is useful in preparing the novel transformer insulating fluid will have at least about 30 carbon atoms per molecule up to about 60 carbon atoms per molecule and preferably will have between about 40 and about 50 carbon atoms per molecule.
• the alpha-olefin oligomer reactant can be prepared from 1-butene, 1-hexene, 1-octene, 1-decene and 1-dodecene or a mixture of two or more of these 1-olefins, with 1-decene preferably being the predominant or only alpha-olefin reactant.
• the oligomer reactant can be an oligomer mixture prepared from oligomer fractions prepared from different 1-olefins or mixtures of 1-olefins.
• the oligomerization reaction can be suitably effected with a boron trifluoride-containing catalyst in a manner well known in the art. Unreacted monomer and dimer are separated from the oligomer product mixture. In the case of 1-decene, the remainder is the trimer, tetramer, pentamer and generally a small amount of higher oligomers, primarily the hexamer, usually comprising no more than a few percent of this mixture.
• This oligomer mixture can be reacted with the aromatic compound without further separation or the trimer can be separated out by vacuum distillation and used separately. Due to difficulty in separation, the tetramer and pentamer of 1-decene are generally utilized as a mixture without separation.
• the alpha-olefin oligomer fraction or a mixture of these oligomer fractions is reacted with an aromatic compound, preferably an aromatic hydrocarbon.
• aromatic compounds include an aromatic hydrocarbon having from six to eight carbon atoms such as benzene, toluene, xylene and ethylbenzene and also include naphthalene, diphenyl ether, chlorobenzene, bromobenzene, and the like.
• the reaction is preferably carried out under conditions and proportions of reactants directed to the monoaIky1ation of the aromatic compound, although the dialkylated product can be prepared by using a substantial excess of the oligomer and this material is also useful as a transformer fluid hereunder.
• reaction product is a mixture of the mono and dialkylate.
• Anhydrous aluminum trichloride is a suitable catalyst for preparing the novel insulating fluid.
• a reaction temperature of between about 15° and about 80° C , preferably between about 20° and about 40° C. is suitable for the alkylation reaction.
• a small amount of water or hydrogen chloride gas must be added to the reactor. The water naturally present in non-dried reactants may be sufficient for this purpose.
• the 1-olefin oligomer compositions used in the following examples were prepared from 1-decene by the method described in U. S. Patent No. 4,045,507.
• the kinematic viscosities were determined by ASTM D445, the viscosity index by ASTM D2270, the pour point by ASTM D97, flash point and fire point by ASTM D92, the oxidation stability by ASTM D2440, the gassing tendency by ASTM D2300B, the power factor and dielectric constants by ASTM D924 and the dielectric strength by ASTM D877.
• Example 1 A reaction between dried benzene and a dried
• 1-decene oligomer was carried out in a 30 gallon, glass-lined, stirred tank reactor under a nitrogen atmosphere.
• the composition of the 1-decene oligomer was 6.5 weight percent trimer, 53.0 percent tetramer and 40.5 percent pentamer.
• a total of 29.83 kg. of benzene, 557. g. of anhydrous aluminum trichloride, 36.5 g. of hydrogen chloride gas and 20.13 kg. of the 1-decene oligomer were charged to the reactor.
• the temperature was maintained within the range of 21-23° C. over a nine and one-half hour period.
• the catalyst which had settled out as a red, insoluble liquid, was deactivated and separated from the product.
• the product liquid was analyzed by NMR and it was determined that there was no unreacted olefin in the reactor and that the product was all mono-alkylate.
• the product was distilled to remove excess benzene and lower boiling components. The bottoms portion weighed 18.43 kg. which was 89.9 percent of the total product giving a yield of 99.3 percent based on the 1-decene tetramer and higher portion of the feed.
• This oligomer-benzene product was analyzed and compared in Table I with a commercially available heavy paraffinic mineral oil and a silicone fluid used as a transformer fluid, technically polydimethylsiloxane but commonly called dimethyl silicone.
• Example 2 The following reaction was carried out in a two-liter, three-necked round-bottom flask equipped with a stirrer and heating mantle. A 780 g. quantity of benzene was charged into the reactor. After purging with nitrogen 13.3 g. of aluminum trichloride catalyst were added with stirring. A 590 g. portion of the tetramer fraction of a 1-decene oligomer was added dropwise over a one-hour period to maintain the temperature between 30° and 40° C. The tetramer fraction had a 98.9° C. (210° F. ) viscosity of
• Example 3 Example 2 was repeated at room temperature. The properties of the product are set out in Table II.
• Example 4 Example 4
• Example 2 was repeated except that 920 g. of toluene were used in place of the benzene.
• the product was acid washed and neutralized with base.
• a 639 g. product was obtained after stripping off light ends to a final pot temperature of 300° C. at 4.0 mm. Hg.
• the results of the various tests are set out in Table II.
• Example 5 A monoalkylate of benzene was made by reacting it with a trimer fraction of 1-decene. This trimer fraction analyzed 100 percent trimer by gas chromato graph. One grammol of this trimer fraction was reacted with 10 grammols of benzene using 0.1 grammol of aluminum trichloride at a maximum temperature of 40°C. over a period of 24 hours.
• Example 7 One grammol of the 100 percent trimer fraction was reacted with five grammols of diphenyl using 0.2 grammol of aluminum trichloride at a maximum temperature of 49° C. for 24 hours. A 44 percent yield of the 1:1 reaction product was obtained having a 298.9° C. (570° F.) flash point and a 316° C. (600° F.) fire point.
• Example 8 In a second reaction 0.2 grammol of the 100 percent trimer fraction was reacted with one grammol of diphenyl using 0.04 grammol of aluminum trichloride at a maximum temperature of 34° C. for 72 hours. There was a 59 percent yield of the monoalkylate of diphenyl.
• This product demonstrated a flash point of 298.9° C. (570° F.), a fire point of 323.9° C. (615° F.), a 98.9° C. (210° F.) viscosity of 15.6 cs. and a pour point of -34.4° C. (-30° F.).
• Example 9 Diphenyl was also reacted with the tetramer fraction described in Example 2. Two-thirds of a grammol of the tetramer fraction were reacted with two-thirds of a grammol of diphenyl using 0.13 grammol of aluminum trichloride at a maximum temperature of 25° C. and a reaction time of 144 hours. There was a 70 percent yield of the diphenyl monoalkylate. It showed a flash point of 310° C. (590° F.), and a fire point of 329.4° C. (625° F.), and possessed a 98.9° C. (210° F.) viscosity of 19.72 cs. and a pour point of -34.4° C. (-30° F.).
• Example 10 One grammol of naphthalene was reacted with 0.2 grammol of the 100 percent trimer fraction using 0.02 grammol of aluminum trichloride at a maximum reaction temperature of 44° C. and a reaction time of 24 hours. There was a 68 percent yield of the desired reaction product which exhibited a flash point of 282.2° C. (540° F.) and a fire point of 310° C. (590° F.).
• Example 11 A 0.7 grammol of naphthalene was reacted with 0.7 grammol of the tetramer fraction described in Example 2 using 0.14 grammol of aluminum trichloride at a maximum temperature of 24° C. and a reaction time of 24 hours.
• the monoalkylated reaction product was obtained in 76 percent yield. It possessed a 98.9° C. (210° F.) viscosity of 18.34 and a pour point of -37.2° C. (-35° F.) and exhibited a flash point of 298.9° C. (570° F.) and a fire point of 323.9° C. (615° F.).
• Example 12 A 0.7 grammol of naphthalene was reacted with 0.7 grammol of the tetramer fraction described in Example 2 using 0.14 grammol of aluminum trichloride at a maximum temperature of 24° C. and a reaction time of 24 hours.
• the monoalkylated reaction product was obtained in
• a 0.34 grammol portion of the 100 percent trimer fraction was reacted with 0.34 grammol of diphenyl ether using 0.06 grammol of aluminum trichloride at a maximum reaction temperature of 28° C. and a reaction time of 48 hours.
• the monoalkylate had a 98.9° C.
• Example 13 In another reaction 0.66 grammol of diphenyl ether was reacted with the tetramer fraction described in Example 2 using 0.13 grammol of aluminum trichloride at a maximum temperature of 26° C. and a reaction time of 24 hours. The product exhibited a flash point of 310° C. (590° P.), a fire point of 340.5° C. (645° F.), a 98.9° C. (210° F.) viscosity of 21.8 cs. and a pour point of -31.7° C. (-25° F.).
• Example 2 using 0.2 grammol of aluminum trichloride at a maximum reaction temperature of 80° C. for 24 hours.
• the yield of the monoalkylate was 42 percent. It exhibited a flash point of 293.2° C. (560° F.) and a fire point of 321.1° C. (610° F.).
• Example 15 Example 14 was repeated using 0.02 grammol of aluminum trichloride, a maximum temperature of 40° C. and a 20 hour reaction period. The yield increased to 68 percent while the flash point and fire point remained the same.
• Example 16 Example 15 was repeated except that bromobenzene replaced the chlorobenzene. The yield was 57 percent, the flash point was 290.5° C. (555° F.) and the fire point was 315.5° C. (600° F.).
• Example 17 A 2.34 kg. quantity of benzene was placed in a twelve-liter, three-necked round-bottom flask equipped with a magnetic stirrer. The system was purged with nitrogen and 40 g. of anhydrous aluminum trichloride were added. A 1.77 kg. quantity of the tetramer fraction as described in Example 2 was added dropwise over a 35 minute period. The temperature rose from 23° C. to 45° C. After 24 hours the contents of the reactor were poured into three liters of water, were washed with dilute sodium hydroxide and dried over anhydrous sodium sulfate. Benzene and the light ends were removed to a maximum pot temperature of 328° C. at 1.7 mm. Hg. The product was 1.86 kg. of a mono-alkylate having a flash point of 285° C. (545° F.) and a fire point of 312.8° C. (595° F.).
• Example 18 Example 17 was repeated. When the product was stripped of light ends at a maximum pot temperature of 324° C. and 1.5 mm. Hg., 1.745 kg. of alkylate were obtained having a flash point of 285° C. (545° F.) and a fire point of 310° C. (590° F ).
• the products of Examples 17 and 18 were mixed and the resulting product exhibited a 98.9° C. (210° F.) viscosity of 10.6 cs., a viscosity index of 115, a pour point of -45.6° C. (-50° F.), a flash point of 296.1° C. (565° F.), a fire point of 312.8° C. (595° F.), a dielectric strength of 46 kV. a power factor at 25° C. of 0.003 and at 100° C. of 0.70 and a gassing tendency of -4.0 mm 3 /min.
• the product yield for these two reactions was 100 percent based on the 1-decene oligomer fed to the reaction.
• Examples 19-25 A series of experiments were carried out using benzene and the tetramer fraction described in Example 2 to evaluate the effect of variations in the reactants and catalyst and in the reaction time.
• 390 g. of benzene and 13.3 g. of aluminum trichloride were added to a two-liter, nitrogen purged flask equipped with a magnetic stirrer.
• a 590 g. quantity of the 1-decene oligomer was charged to the reactor as rapidly as possible while maintaining the temperature at 40-50° C. Neither the benzene nor the oligomer was dried to permit trace water to catalyze the reaction. After about four hours the temperature dropped slowly and after 24 hours it was at room temperature (20-25° C.).
• the product was treated with a series of dilute hydrochloric acid, dilute sodium hydroxide and distilled water washings until it was neutral. It was dried and the excess benzene was removed and then stripped of the light ends, including any alkylate of the trimer present, at a pot temperature of 325° C. and a pressure of 1.4 mm. Hg.
• Example 19 which involved a benzene to oligomer ratio of 5:1 while in Example 21 which used a benzene to oligomer ratio of 10:1, no oligomer was detected after one hour.
• a comparison of Examples 19 and 20 or 22 and 23 suggests that reactions are taking place after four hours of reaction time and that this additional reaction time is necessary to increase the fire point of the product.
• a comparison of Examples 19 with 22 and 20 with 23 indicates that insufficient aluminum trichloride catalyst also decreases the fire point of the product while a comparison of Examples 22 and 25 indicates that excess aluminum trichloride can produce the same fire point in a much shorter reaction time.
• Example 26 The 1-decene oligomer described in Example 1 was reacted with toluene in a two liter reactor. Although the feed was undried, 1.8 g. of hydrogen chloride was used to insure reaction. The other components comprised 731.4 g. of toluene, 675 g. of the 1-decene oligomer and 13.3 g. of aluminum trichloride. The reactor was maintained at a temperature between 24° and 35° C. for a period of 24 hours. The excess toluene and lower boiling components were distilled off. The product yield was determined to be 102 percent based on the 1-decene tetramer and higher portion of the feed.
• This product was found to have a 98.9° C. (210° F.) viscosity of 13.6 cs., a 37.8° C. (100° F.) viscosity of 129.5 cs., a viscosity index of 110, a pour point of -40° C., a flash point of 296.1° C. (565° F.) and a fire point of 323.9° C. (615° F.). It was found to have a gassing tendency of -7.4 mm 3 /min. The power factor at 25° C. (77° F.) was determined to be 0.005 and 0.100 at 100° C. and the dielectric strength was found to be 0.30 kV.

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• Oil, Petroleum & Natural Gas (AREA)
• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Lubricants (AREA)
• Organic Insulating Materials (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Transformer Cooling (AREA)

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• 1979
  • 1979-09-12 WO PCT/US1979/000733 patent/WO1980000894A1/fr not_active Ceased
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