JP2009283445A - Composition for insulating oil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for insulating oil having high biodegradability, stability and low-temperature fluidity at the same time. <P>SOLUTION: The composition for insulating oils contains a fatty acid ester, wherein the total of an ester of a 18C monoene unsaturated fatty acid (hereinafter referred to as 'fatty acid A'), an ester of a 18C diene unsaturated fatty acid (hereinafter referred to as 'fatty acid B') and an ester of a resin acid is not less than 75 wt.% in 100 wt.% of the fatty acid ester. When the total of the fatty acid ester is taken as 100 wt.%, the content ratios of the ester of the fatty acid A, the ester of the fatty acid B and the ester of the resin acid are respectively, 25-70 wt.%, 20-60 wt.% and 0.1-15 wt.%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an insulating oil composition containing an ester of fatty acid.

  Insulating oil is an insulating material that serves to insulate electrical equipment such as transformers, circuit breakers, and capacitors and to cool generated heat. Since the insulating oil is used for a long time, conventionally, PCB (polychlorinated biphenyl) having excellent nonflammability has been widely used. Nonflammability is a necessary physical property in order to reduce the risk of fire and explosion damage when an electrical failure occurs in the equipment. However, from the viewpoint of environmental protection, PCB has been found to be harmful to the environment, and mineral oil or the like has been used in place of PCB. In recent years, from the viewpoints of biodegradability and stability, the use of polyol fatty acid esters, vegetable oils and the like useful as lubricating oil components has also been studied (see, for example, Patent Document 1 and Patent Document 2).

  On the other hand, fatty acid esters containing fatty acids typified by tall oil fatty acids are conventionally used as resin components, as fuel additives (see, for example, Patent Document 3), and as lubricating oil oil agents (additives) ( For example, see Patent Document 4). These fatty acid esters are only used in small amounts as additives as described above, and have not been used under harsh conditions, for example, conditions required for lubricating oil main ingredients. Note that tall oil fatty acid esters have also been reported to be used as hydraulic oils (see, for example, Patent Document 5).

JP 2005-276714 A Japanese National Patent Publication No. 12-502493 JP-T 2005-53464 JP 2003-252829 A Special Table 2000-506214

  However, the tall oil fatty acid ester as a hydraulic oil disclosed in Patent Document 3 is produced from an ester of a tall oil containing a fatty acid, a resin acid and an unsaponifiable component and a dihydric or polyhydric alcohol. And the typical composition of this tall oil fatty acid ester contains 20-40% resin acid ester, 50-75% fatty acid ester, and 3-15% unsaponifiable component, and the resin acid ester content is compared High and not fully purified. Therefore, it is considered that such tall oil fatty acid ester does not have physical properties enough to withstand use under severe conditions.

  In addition, the insulating oil is required to have low-temperature fluidity because it functions not only in biodegradability and stability but also in a device at low temperatures. However, the above-mentioned polyol fatty acid esters and vegetable oils have a problem that the low-temperature fluidity is insufficient for insulating oils. Further, the tall oil fatty acid ester has been considered to lack physical properties necessary for use under severe conditions.

  The problem to be solved by the present invention is a composition for insulating oil that can constitute an insulating oil having high biodegradability, stability, and low temperature fluidity, a fatty acid composition used for the production of the composition for insulating oil, and insulation. Is to provide oil.

In order to achieve the above object, the present inventor has focused on tall oil fatty acid esters. The present inventor is the first to show that tall oil fatty acid containing a specific fatty acid and a resin acid in a specific ratio is converted into an ester, has excellent biodegradability, high stability, and excellent low-temperature fluidity. I found it.
Based on this knowledge, the present inventors are able to solve the above-mentioned problems by using, as an insulating oil composition, a fatty acid ester containing a specific fatty acid and a resin acid as constituent components in a specific ratio. The headline and the present invention were completed.

  That is, the present invention is a composition for insulating oil containing an ester of a fatty acid, wherein the ester of a monoene unsaturated fatty acid having 18 carbon atoms (hereinafter referred to as fatty acid A), When the total amount of esters of diene unsaturated fatty acid (hereinafter referred to as fatty acid B) and ester of resin acid is 75% by weight or more, and the total amount of esters of fatty acid is 100% by weight, the ester of fatty acid A, the fatty acid The content ratios of the ester of B and the ester of the resin acid are 25 to 70% by weight, 20 to 60% by weight, and 0.1 to 15% by weight, respectively.

  The present invention also relates to an insulating oil containing an ester of fatty acid (hereinafter also referred to as a fatty acid ester composition for insulating oil), which is a monoene unsaturated fatty acid having 18 carbon atoms (fatty acid A) in 100% by weight of the fatty acid ester. ), The total amount of esters of diene unsaturated fatty acid having 18 carbon atoms (fatty acid B), and ester of resin acid is 75% by weight or more, and the total of the esters of fatty acid is 100% by weight, The contents of the fatty acid A ester, the fatty acid B ester, and the resin acid ester are 25 to 70% by weight, 20 to 60% by weight, and 0.1 to 15% by weight, respectively.

  Moreover, this invention is a fatty acid composition used for manufacture for the fatty-acid-ester composition for insulating oils, Comprising: In 100 weight% of the said fatty acid, C18 monoene unsaturated fatty acid (fatty acid A), C18 When the total amount of the diene unsaturated fatty acid (fatty acid B) and the resin acid is 75% by weight or more and the total amount of the fatty acid is 100% by weight, the content ratio of the fatty acid A, the fatty acid B, and the resin acid Are 25-70 wt%, 20-60 wt% and 0.1-15 wt%, respectively.

  ADVANTAGE OF THE INVENTION According to this invention, the composition for insulating oils which can comprise the insulating oil excellent in low-temperature fluidity | liquidity, stability, and biodegradability, the fatty acid composition used for manufacture of the said composition for insulating oils, and insulating oil are provided. The

  Physical properties of insulating oil composition of the present invention and insulating oil of the present invention, esters of fatty acids contained therein, specific embodiments and preferred embodiments other than the esters of fatty acids, blended forms thereof, fatty acid composition of the present invention Products, fatty acids contained therein, specific embodiments and preferred embodiments other than the fatty acids, and blending forms thereof are common. Therefore, unless otherwise specified, the description relating to the insulating oil composition of the present invention will be valid even if the insulating oil composition of the present invention is replaced with the insulating oil of the present invention. The description regarding the fatty acid used for the production of the composition also holds true for the fatty acid composition of the present invention.

  The composition for insulating oil and the insulating oil of the present invention contain an ester of fatty acid as described above. In the composition for insulating oil and the insulating oil of the present invention, when the composition for insulating oil and the insulating oil are 100% by weight, the fatty acid ester is preferably 70% by weight or more, more preferably 80% by weight or more, and still more preferably. Contains 85% by weight or more, more preferably 90% by weight or more. In 100% by weight of the ester of fatty acid, the total amount of ester of monoene unsaturated fatty acid having 18 carbon atoms (fatty acid A), ester of diene unsaturated fatty acid having 18 carbon atoms (fatty acid B), and ester of resin acid is Thus, it is 75% by weight or more, preferably 80% by weight or more, and more preferably 83% by weight or more. By having such a composition, specifically, the amount of unsaturated fatty acid ester and the amount of saturated fatty acid ester are low, so that the pour point of the composition for insulating oil and the insulating oil of the present invention is lowered, that is, at a low temperature. Fluidity is improved. Further, the composition for insulating oil and the insulating oil of the present invention have a low acid value, that is, extremely low corrosiveness to metals and excellent stability. Furthermore, the composition for insulating oil and the insulating oil of the present invention are superior in biodegradability as compared with conventional mineral oils.

[fatty acid]
In the present invention, examples of the fatty acid A constituting the monoene unsaturated fatty acid having 18 carbon atoms (fatty acid A) and the ester of the fatty acid A include cis-6-octadecenoic acid (petroceric acid), trans-6-octadecene. Acid (petrocelaidic acid), cis-9-octadecenoic acid (oleic acid), trans-9-octadecenoic acid (elaidic acid), cis-11-octadecenoic acid (cis-vaccenoic acid), trans-11-octadecenoic acid ( Cis-9-octadecenoic acid (oleic acid) is preferred.

  In the present invention, the fatty acid ester includes, in addition to the fatty acid A ester, the fatty acid B ester, and the resin acid ester, a monoene unsaturated fatty acid (hereinafter, fatty acid a) having 16, 20, or 22 carbon atoms. The ester may also be included. In that case, the ester of the fatty acid a is, for example, 25 parts by weight or less, preferably 20 parts by weight or less, with respect to 100 parts by weight of the total amount of the fatty acid A ester, the fatty acid B ester, and the resin acid ester. More preferably, it is 15 parts by weight or less. In the present invention, the fatty acid may further include a monoene unsaturated fatty acid (fatty acid a) having 16, 20, or 22 carbon atoms in addition to the fatty acid A, the fatty acid B, and the resin acid. In that case, the fatty acid a is, for example, 25 parts by weight or less, preferably 20 parts by weight or less, more preferably 15 parts by weight or less with respect to 100 parts by weight of the total amount of the fatty acid A, the fatty acid B and the resin acid. is there.

  Examples of the monoene unsaturated fatty acid (fatty acid a) having 16, 20 or 22 carbon atoms and the fatty acid a constituting the ester of the fatty acid a include 2-hexadecenoic acid (2-palmitoleic acid) and 7-hexadecene. Acid (7-palmitoleic acid), cis-9-hexadecenoic acid (palmitoleic acid), trans-9-hexadecenoic acid (trans-9-palmitoleic acid), cis-9-icosenoic acid (gadelic acid), cis-11-icosene Acid (gondoic acid), trans-11-icosenoic acid (trans-gondoic acid), cis-11-docosenoic acid (cetoleic acid), cis-13-docosenoic acid (erucic acid), trans-13-docosenoic acid (brassic acid) ) And the like.

  In the present invention, examples of the fatty acid B constituting the diene unsaturated fatty acid having 18 carbon atoms (fatty acid B) and the ester of the fatty acid B include, for example, cis-9, cis-12-octadecadienoic acid (linoleic acid). , Trans-9, trans-12-octadecadienoic acid (linoelaidic acid), cis-9, trans-11-octadecadienoic acid, trans-10, cis-12-octadecadienoic acid, cis-9, cis -11-octadecadienoic acid, cis-10, cis-12-octadecadienoic acid, trans-10, trans-12-octadecadienoic acid, trans-9, trans-11-octadecadienoic acid, trans-8 , Trans-10 octadecadienoic acid, and the like, and cis-9, cis-12-octadecadienoic acid (linoleic acid) is preferred.

  In the present invention, in addition to the fatty acid A ester, the fatty acid B ester, and the resin acid ester, the fatty acid ester further includes a diene unsaturated fatty acid having 16, 20, or 22 carbon atoms (hereinafter, fatty acid b). The ester may also be included. In that case, the ester of the fatty acid b is, for example, 25 parts by weight or less, preferably 20 parts by weight or less, with respect to 100 parts by weight of the total amount of the fatty acid A ester, the fatty acid B ester and the resin acid ester. More preferably, it is 15 parts by weight or less. In the present invention, the fatty acid may further include a diene unsaturated fatty acid (fatty acid b) having 16, 20, or 22 carbon atoms in addition to the fatty acid A, the fatty acid B, and the resin acid. In that case, the fatty acid b is, for example, 25 parts by weight or less, preferably 20 parts by weight or less, more preferably 15 parts by weight or less with respect to 100 parts by weight of the total amount of the fatty acid A, the fatty acid B, and the resin acid. is there.

  The diene unsaturated fatty acid (fatty acid b) having 16, 20 or 22 carbon atoms and the fatty acid b constituting the ester of the fatty acid b include, for example, cis-9, cis-12-hexadecadienoic acid, trans -9, trans-12-hexadecadienoic acid, cis-9, trans-12-hexadecadienoic acid, trans-9, cis-12-hexadecadienoic acid, cis-8, cis-11-icosadienoic acid, trans -8, trans-11-icosadienoic acid, cis-8, trans-11-icosadienoic acid, trans-8, cis-11-icosadienoic acid, cis-5, cis-13-docosadienoic acid, trans-5, trans-13 -Docosadienoic acid, cis-5, trans-13-docosadienoic acid, trans-5, cis-13-docosadienoic acid and the like.

  In the present invention, the fatty acid ester may include, in addition to the fatty acid A ester, the fatty acid B ester, and the resin acid ester, an ester of a triene unsaturated fatty acid having 18 carbon atoms (hereinafter, fatty acid C). Good. In that case, from the viewpoint of maintaining stability in the presence of air and low-temperature fluidity, the ester of the fatty acid C is in a total amount of 100 parts by weight of the ester of the fatty acid A, the ester of the fatty acid B, and the ester of the resin acid. On the other hand, it is 0.01-10 weight part, for example, Preferably it is 0.01-8 weight part, More preferably, it is 0.01-5 weight part. Further, in the present invention, the fatty acid may further contain a triene unsaturated fatty acid having 18 carbon atoms (fatty acid C) in addition to the fatty acid A, the fatty acid B, and the resin acid. In that case, from the viewpoint of maintaining stability in the presence of air and low temperature fluidity, the fatty acid C is, for example, 0.01 to 100 parts by weight with respect to 100 parts by weight of the total amount of the fatty acid A, the fatty acid B, and the resin acid. 10 parts by weight, preferably 0.01 to 8 parts by weight, more preferably 0.01 to 5 parts by weight.

  Examples of the fatty acid C constituting the C18 triene unsaturated fatty acid (fatty acid C) and the ester of the fatty acid C include, for example, cis-9, cis-12, cis-15-octadecatrienoic acid (α- Linolenic acid), cis-6, cis-9, cis-12-octadecatrienoic acid (γ-linolenic acid), trans-9, trans-12, trans-15-octadecatrienoic acid (linolenic elaidic acid), cis -9, trans-11, trans-13-octadecatrienoic acid (α-eleostearic acid), trans-9, trans-11, trans-13-octadecatrienoic acid (β-eleostearic acid), cis -9, trans-11, cis-13-octadecatrienoic acid (punicic acid), trans-10, trans-12, trans-14-octadecatrienoic acid and the like, and cis-9, cis-12, cis -15-octadecatrienoic acid α- linolenic acid), cis-6, cis-9, cis-12- octadecatrienoic acid (.gamma.-linolenic acid) and the like are preferable.

  In the present invention, the fatty acid ester includes, in addition to the fatty acid A ester, the fatty acid B ester, and the resin acid ester, a triene unsaturated fatty acid having 16, 20, or 22 carbon atoms (hereinafter, fatty acid c). The ester may also be included. In that case, the ester of the fatty acid c is, for example, 10 parts by weight or less, preferably 7 parts by weight or less, with respect to 100 parts by weight of the total amount of the fatty acid A ester, the fatty acid B ester, and the resin acid ester. More preferably, it is 5 parts by weight or less. In the present invention, the fatty acid may further contain a triene unsaturated fatty acid (fatty acid c) having 16, 20, or 22 carbon atoms. In that case, the fatty acid c is, for example, 10 parts by weight or less, preferably 7 parts by weight or less, more preferably 5 parts by weight or less with respect to 100 parts by weight of the total amount of the fatty acid A, the fatty acid B and the resin acid. is there.

  Examples of the fatty acid c constituting the triene unsaturated fatty acid (fatty acid c) having the carbon number 16, 20, or 22 and the ester of the fatty acid c include, for example, cis-9, cis-12, cis-15-hexadeca Trienoic acid, trans-9, trans-12, trans-15-hexadecatrienoic acid, cis-5, cis-8, cis-11-icosatrienoic acid, trans-5, trans-8, trans-11-icosatrienoic acid, Examples thereof include cis-13, cis-16, cis-19-docosatrienoic acid, trans-13, trans-16, trans-19-docosatrienoic acid, and the like.

  In the present invention, the resin acid contained in the resin acid and the ester of the resin acid is monocarboxylic diterpenic acid, for example, abietic acid, dihydroabietic acid, tetrahydroabietic acid, dehydroabietic acid, neoabietic acid, pimaru Acid, levopimaric acid, pulse phosphoric acid, isopimaric acid and the like.

  In the present invention, the content ratio of the fatty acid A ester, the fatty acid B ester, and the resin acid ester is 25 to 70% by weight when the total fatty acid ester is 100% by weight as described above. %, 20 to 60% by weight and 0.1 to 15% by weight, preferably 25 to 65% by weight, 20 to 60% by weight and 0.2 to 15% by weight, more preferably 25 to 65% by weight. 65 wt%, 25-55 wt% and 0.2-15 wt%, more preferably 30-60 wt%, 25-55 wt% and 0.2-15 wt%, even more preferred Is 35-60 wt%, 30-50 wt% and 0.3-15 wt%, even more preferably 35-60 wt%, 30-50 wt% and 0.3-10 wt%, Better Properly from 35 to 60 wt%, 30 to 50 wt% and 0.3 to 5 wt%, even more preferably 35 to 60 wt%, 30 to 50 wt% and 0.3 to 2% by weight.

  In the present invention, when the total fatty acid ester is 100% by weight, the total of the fatty acid A ester and the fatty acid B ester, and the resin acid ester content, 95 wt% and 0.1 to 15 wt%, more preferably 65 to 90 wt% and 0.2 to 15 wt%, still more preferably 70 to 90 wt% and 0.3 to 15 wt% More preferably 70 to 90% by weight and 0.3 to 10% by weight, even more preferably 70 to 90% by weight and 0.3 to 5% by weight, even more preferably 70 to 90% by weight. % And 0.3-2% by weight.

  In the present invention, the fatty acid is preferably derived from tall oil fatty acid. This is because the tall oil fatty acid is obtained from the waste liquid during pulp production, so that the waste can be used effectively. The tall oil fatty acid can be obtained, for example, from pine grown in a specific habitat. The specific habitat is preferably a cold region such as Northern Europe or North America. This is because a product containing a specific fatty acid and a resin acid in a specific ratio in the present invention can be obtained. The tall oil fatty acid can be obtained by distilling and fractionating crude tall oil. Examples of the distillation include steam distillation. By the steam distillation, the crude tall oil can be fractionated into tall oil fatty acid, resin acid, pitch and the like. Further, when tall oil fatty acid is used in the present invention, the fatty acid A, the fatty acid B, and the resin acid are purified from the viewpoint of thermal stability and oxidative stability, so that the composition for insulating oil of the present invention, insulation is obtained. It is preferable to use a mode suitable for the oil or fatty acid composition. Such purification can be performed by, for example, fractionation by distillation, steam distillation or the like. Examples of commercially available tall oil fatty acids include Hartle Chemicals Co., Ltd. Hartle FA-1 (trade name), Hartle FA-1P (trade name), and Arizona Chemical Co., Ltd. SYLFAT 2LT (trade name).

  In the present invention, the difference between the acid value and saponification value of the fatty acid constituting the ester correlates with the amount of impurities, and is preferably 5 mgKOH / g or less. The saponification value (SV) in the present invention is a saponification value measured based on JIS-K0070 (1992). The acid value (AV) of the present invention is an acid value measured based on JIS-K2501 “Petroleum products and lubricants—neutralization test method” (2003).

  In the present invention, the iodine value of the fatty acid constituting the ester is preferably 100 to 160 from the viewpoint of lowering the pour point and enhancing the stability. The iodine value of the present invention is an iodine value measured based on JIS-K0070 (1992).

  Furthermore, the cloud point of the fatty acid constituting the ester in the present invention is preferably 10 ° C. or less, more preferably 6 ° C. or less, from the viewpoint of lowering the pour point of the insulating oil composition. The cloud point of the present invention is a value measured based on JIS-K2269 (1987).

[Fatty acid ester]
In the present invention, the fatty acid ester is an ester obtained from the fatty acid and an alcohol, and the alcohol is preferably an aliphatic alcohol having 1 to 6 hydroxy groups. Examples of the aliphatic alcohol having 1 to 6 hydroxy groups include C 1-12 aliphatic hydrocarbons having 1 to 6 hydroxy groups. Examples of the C1-C12 aliphatic hydrocarbon having 1 to 6 hydroxy groups include methanol, ethanol, butanol, propanol; ethylene glycol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol) 1,3-butanediol; glycerin, trimethylolethane, trimethylolpropane, trimethylolbutane; pentaerythritol, erythritol; arabitol; sorbitol, mannitol, etc. are preferred, and trimethylolpropane, pentaerythritol, trimethylolethane, trimethylolbutane , Neopentyl glycol, and glycerin are more preferable, and glycerin is more preferable. In the present invention, the ester preferably includes the fatty acid A and alcohol ester, the fatty acid B and alcohol ester, and the resin acid and alcohol ester. In the present invention, the alcohol in the fatty acid A and alcohol ester, the alcohol in the fatty acid B and alcohol ester, and the alcohol in the resin acid and alcohol ester are the same or different. Also good.

  In the present invention, the ester may be produced by reacting the fatty acid and the alcohol without using a catalyst or optionally mixing them in a solvent in the presence of a catalyst. Examples of the catalyst include acid catalysts such as sulfuric acid and paratoluenesulfonic acid, and metal catalysts such as tin chloride and titanium chloride. The reaction ratio between the fatty acid and the alcohol is preferably such that the fatty acid is excessive with respect to the alcohol. Specifically, reacting an alcohol and a fatty acid at an equivalent ratio of fatty acid / alcohol = 1.0 to 1.4, and further 1.05 to 1.3 from the viewpoint of improving the reaction rate of esterification. preferable.

  The conditions for the esterification reaction between the fatty acid and the alcohol include, for example, when the alcohol and the fatty acid are reacted at an equivalent ratio of fatty acid / alcohol = 1.0 to 1.4, the reaction temperature is 180 to 260 ° C., the reaction time. Is 5 to 15 hours, and the reaction pressure is 13 to 101 kPa. The end point of the esterification reaction may be based on the hydroxyl value in the reaction product. Preferably, the end point may be the time point when the hydroxyl value of the reaction product is 5 mgKOH / g or less. For example, when the alcohol is glycerin, the esterification reaction between the fatty acid and the alcohol is performed under a nitrogen stream at 230 to 250 ° C. under normal pressure for 5 to 12 hours, until the hydroxyl value becomes 5 mgKOH / g or less. I do.

  The ester is preferably purified by performing necessary treatments such as deoxidation, water washing, dehydration, decolorization, and filtration. When the fatty acid is used in excess relative to the alcohol, it is preferable to remove unreacted fatty acid from the reaction product of the fatty acid and the alcohol (hereinafter referred to as “deoxidation”). Specifically, the reaction product is treated under reduced pressure to remove fatty acids from the reaction product. The fatty acid removed by the reduced pressure treatment can be recovered and used as a reaction raw material for another ester. Alternatively, an adsorbent capable of adsorbing fatty acid may be added to the reaction product, the fatty acid may be adsorbed by the adsorbent, and the adsorbent may be removed to remove the fatty acid. As the method for removing the fatty acid, the reduced pressure treatment is more preferable than the method using an adsorbent from the viewpoint of removal efficiency and reuse of the fatty acid.

  The removal of the unreacted fatty acid remaining in the reaction product can be performed based on the acid value in the reaction product. Specifically, the reaction product is reduced in pressure until the acid value of the reaction product is preferably 0.5 mgKOH / g or less, more preferably 0.3 mgKOH / g or less, and still more preferably 0.2 mgKOH / g or less. What is necessary is just to process.

  The reaction product previously deoxidized may be decolorized. The decolorization is preferably performed by bringing an adsorbent having an ability to adsorb a dye (hereinafter referred to as “decolorizing adsorbent”) into contact with a reaction product. Examples of the decolorizing adsorbent include activated carbon and activated clay. These decolorizing adsorbents are preferably used in an amount of 0.1 to 1.5% by weight based on the reaction product, depending on the degree of coloration of the reaction product.

  When it is necessary to further reduce the acid value of the ester, the fatty acid can be removed by contacting an adsorbent capable of adsorbing a fatty acid (hereinafter referred to as “acid adsorbent”) with a reaction product deoxidized in advance. It is preferable to carry out. Examples of the acid adsorbent include activated alumina, activated clay, aluminum hydroxide, synthetic zeolite having anion exchange adsorption ability, ion exchange resin or hydrotalcite. The acid adsorbent is preferably used at a ratio of 0.1 to 2.0% by weight with respect to the reaction product. The acid adsorbent and the decolorizing adsorbent may be added and used simultaneously, or the acid adsorbent may be used after decolorization.

  In addition, although the composition for insulating oil of the present invention and the insulating oil of the present invention may contain only the ester of the fatty acid, the range does not impair the effects of the present invention that are excellent in low-temperature fluidity, stability and biodegradability. In addition, you may further contain components other than the ester of the said fatty acid. However, it is preferable not to include conductive compounds such as metals and metal salts from the viewpoint of reducing electrical insulation.

[Additive]
In order to further improve the performance of the insulating oil composition of the present invention and the insulating oil of the present invention, the insulating oil composition and the insulating oil of the present invention may further contain an additive. Examples of the additive include phenolic antioxidants such as di-tert-butyl-p-cresol and bisphenol A, phenyl-α-naphthylamine, N, N-di (2-naphthyl) -p-phenylenediamine. Amine-based antioxidants such as benzotriazole, antimicrobial agents such as vitamin E, pour point depressants such as polyvinyl acetate oligomers, polyvinyl acetate polymers, acrylic acid oligomers and acrylic acid polymers, carbodiimides And a diluent such as alkyl glycidyl ether having 5 to 18 carbon atoms and alkyl glycidyl ester. The content of these additives is not particularly limited, but is, for example, 2.0% by weight or less, preferably 1.5% by weight or less, more preferably 1.0% by weight, based on the composition for insulating oil and the whole insulating oil. % Or less.

  Moreover, as described above, the present invention is a fatty acid composition for an insulating oil composition containing an ester of fatty acid, wherein the total amount of fatty acid A, fatty acid B and resin acid is 100% by weight of the fatty acid. It is 75% by weight or more, preferably 80% by weight or more, and more preferably 83% by weight or more. Moreover, the content rate of the said fatty acid A, the said fatty acid B, and the said resin acid is 25 to 70 weight%, 20 to 60 weight%, and 0.1 to 15 weight%, when the whole fatty acid is 100 weight%, respectively. Preferably 25-65 wt%, 20-60 wt% and 0.2-15 wt%, more preferably 25-65 wt%, 25-55 wt% and 0.2-15 wt% More preferably 30-60% by weight, 25-55% by weight and 0.2-15% by weight, even more preferably 35-60% by weight, 30-50% by weight and 0.3-15% by weight. %, Even more preferably 35-60%, 30-50% and 0.3-10%, even more preferably 35-60%, 30-50% and 0.3- 5% by weight , Even more preferably 35 to 60 wt%, 30 to 50 wt% and 0.3 to 2% by weight.

  The fatty acid A, the fatty acid B, and the resin acid are as described above. As this fatty acid composition, tall oil fatty acids are preferred. Moreover, it is the kit for fatty acid compositions for the composition for insulating oil containing the fatty acid A, the fatty acid B, and the resin acid, and containing an ester of fatty acid, and the kit makes the entire kit 100% by weight. In this case, the content ratios of the fatty acid A, the fatty acid B, and the resin acid are 25 to 70 wt%, 20 to 60 wt%, and 0.1 to 15 wt%, respectively, preferably 25 to 65 wt%, 20 to 60% by weight and 0.2 to 15% by weight, more preferably 25 to 65% by weight, 25 to 55% by weight and 0.2 to 15% by weight, and further preferably 30 to 60% by weight. 25 to 55 wt% and 0.2 to 15 wt%, even more preferably 35 to 60 wt%, 30 to 50 wt% and 0.3 to 15 wt%, even more preferably 35 to 60 wt%. weight 30 to 50 wt% and 0.3 to 10 wt%, even more preferably 35 to 60 wt%, 30 to 50 wt% and 0.3 to 5 wt%, and even more preferably 35 to 60 wt%. %, 30-50% and 0.3-2% by weight.

[Physical properties]
Kinematic viscosity at 40 ° C. of the insulating oil composition and an insulating oil of the invention is preferably from the viewpoint of enhancing the cooling effect is 130 mm ² / s or less, more preferably 100 mm ² / s, more preferably less 65 mm ² / s 60 mm ² / s or less is even more preferable. From the viewpoint of not lowering the flash point, the kinematic viscosity at 40 ° C. of the composition for insulating oil and the insulating oil of the present invention is preferably 10 mm ² / s or more, more preferably 13 mm ² / s or more, and 15 mm ² / s. The above is even more preferable. That is, the kinematic viscosity at 40 ° C. of the composition for insulating oil and the insulating oil of the present invention is, for example, 10 to 130 mm ² / s, preferably 10 to 100 mm ² / s, more preferably 13 to 65 mm ² / s, and still more preferably. Is 15 to 60 mm ² / s.

Further, the kinematic viscosity at 100 ° C., preferably in view of enhancing the cooling effect is 20 mm ² / s or less, more preferably 17 mm ² / s, more preferably not more than 15 mm ² / s. Moreover, 2 mm < ² > / s or more is preferable from a viewpoint which does not lower a flash point, 4 mm < ² > / s or more is more preferable, 6 mm < ² > / s or more is still more preferable. That is, the kinematic viscosity at 100 ° C. is, for example, ^{2 to 20} mm ² / s, preferably 4 to 17 mm ² / s, and more preferably 6 to 15 mm ² / s. In addition, in this invention, kinematic viscosity means the kinematic viscosity measured based on JIS-K2283 (2000). Further, the kinematic viscosity at 40 ° C. of the composition for insulating oil and the insulating oil of the present invention is controlled within the range of 10 to 130 mm ² / s, for example, the ester of the fatty acid A, the ester of the fatty acid B, and the resin When the ester of the acid is an ester obtained from tall oil fatty acid and glycerin, it can be achieved by performing the reaction in a nitrogen atmosphere during the esterification reaction to avoid oxidation due to air mixing and polymerization due to high temperature. Similarly, the kinematic viscosity at 100 ° C. of the composition for insulating oil and the insulating oil of the present invention is controlled within the range of ² to 20 mm ² / s, for example, the ester of fatty acid A and the ester of fatty acid B. When the ester of the resin acid is an ester obtained from tall oil fatty acid and glycerin, the reaction can be achieved by performing the reaction in a nitrogen atmosphere during the esterification reaction to avoid oxidation due to air mixing and polymerization due to high temperature. .

  The pour point of the composition for insulating oil and the insulating oil of the present invention is, for example, −70 ° C. to −5 ° C., preferably −70 ° C. to −10 ° C., more preferably −70 ° C. to −20 ° C., and still more preferably − 70 ° C to -30 ° C. If the pour point is in the range of -70 ° C to -5 ° C, it is suitable for use in cold regions. In addition, in this invention, a pour point means the pour point measured based on JIS-K2269 (1987).

  Moreover, the saturated fatty acid contained in the said composition for insulating oil and insulating oil controls the pour point of the composition for insulating oil and insulating oil of this invention to the range of the said -70 to -5 degreeC, for example. The saturated fatty acid in the raw material is preferably 5% by weight or less, more preferably 3% by weight or less, and is contained in the insulating oil composition and the insulating oil. This can be achieved by selecting an ester of a fatty acid having the highest possible iodine value (for example, an iodine value of 70 to 160) and an alcohol having 1 to 6 hydroxyl groups.

  The flash point of the composition for insulating oil and the insulating oil of the present invention is, for example, 250 ° C to 350 ° C, preferably 275 ° C to 350 ° C, more preferably 300 ° C to 350 ° C. If the flash point is 250 ° C. to 350 ° C., it is flame retardant and suitable for use as an insulating oil. In addition, in this invention, flash point means the flash point measured based on JIS-K2265 (1996). Moreover, the molecular weight of the fatty acid ester contained in the composition for insulating oil and the insulating oil, for example, is to control the flash point of the composition for insulating oil and the insulating oil in the range of 250 ° C to 350 ° C. Can be achieved by reducing the vapor pressure to an ester of 470 or more.

  The moisture content of the composition for insulating oil and the insulating oil of the present invention is, for example, 200 ppm or less, preferably 100 ppm or less, more preferably 50 ppm or less. It is because generation | occurrence | production of rust and hydrolysis of ester can be suppressed if water content is 200 ppm or less. In addition, in this invention, water content means the water content measured based on JIS-K2275 (1996). Moreover, the composition for insulating oil of the present invention and the moisture content of the insulating oil are controlled within the range of 200 ppm or less, for example, the composition for insulating oil while introducing nitrogen under reduced pressure at a temperature of 80 ° C. or higher. And by dehydrating the insulating oil.

  The hydroxyl value (OHV) of the composition for insulating oil and the insulating oil of the present invention is, for example, 0.01 to 7.0 (mgKOH / g), preferably 0.01 to 5.0 (mgKOH / g), more preferably. Is 0.01 to 4.0 (mgKOH / g), more preferably 0.01 to 2.0 (mgKOH / g). This is because if the hydroxyl value is 0.01 to 7.0 (mg KOH / g), the thermal stability is high and the hygroscopicity can be suppressed. In addition, in this invention, a hydroxyl value means the hydroxyl value measured based on JIS-K0070 (1992). Moreover, controlling the hydroxyl value of the composition for insulating oil and the insulating oil of the present invention within the range of 0.01 to 7.0 (mg KOH / g) is, for example, the ester of the fatty acid A, the fatty acid B When the ester and the ester of the resin acid are obtained from the fatty acid A, the fatty acid B, and the resin acid and an alcohol, the amount of the fatty acid A, the fatty acid B, and the resin acid is used in an amount equal to or more than the alcohol. This can be achieved by esterification.

  The acid value (AV) of the composition for insulating oil and the insulating oil of the present invention is, for example, 0.001 to 0.1 (mgKOH / g) from the viewpoint of stability and prevention of metal corrosion, and 0.001 to 0. 0.07 (mgKOH / g) is preferable, and 0.001 to 0.04 (mgKOH / g) is more preferable. In order to control the acid value within the above range, for example, the deoxidation step can be carried out by carrying out the reaction until the acid value becomes 0.1 (mgKOH / g).

  The iodine value of the composition for insulating oil and the insulating oil of the present invention is, for example, 70 to 160, preferably 80 to 155, more preferably 90 to 150. This is because if the iodine value is 70 to 160, the pour point is lowered and the oxidation stability can be increased. The iodine value can be controlled by the method for obtaining the fatty acid as a raw material of the fatty acid ester contained in the composition for insulating oil and the insulating oil of the present invention. Specifically, the fatty acid A ester, the fatty acid B ester, and the resin acid ester are obtained from the fatty acid A, the fatty acid B, the resin acid and an alcohol, and the fatty acid A, the fatty acid B, and the resin. When the acid is derived from tall oil fatty acid, impurities are reduced by controlling the conditions of steam distillation from the crude tall oil, and pine derived from a specific habitat as a pine as a further raw material (for example, pine in a cold region, preferably Northern Europe) Or by selecting North American pine). In the present invention, the iodine value means an iodine value measured based on JIS K0070 (1992).

  The composition for insulating oil and insulating oil of the present invention preferably have a saponification value of 220 mgKOH / g or less from the viewpoint of maintaining high volumetric efficiency (insulating properties), and 180 mgKOH / from the viewpoint of preventing the molecular weight from increasing and increasing the viscosity. g or more is preferable. The saponification value (SV) of the present invention is a saponification value measured based on JIS-K0070 (1992).

The composition for insulating oil and insulating oil of the present invention has a volume resistivity of, for example, 1 × 10 ¹³ to 1 × 10 ¹⁸ Ω · cm, preferably 3 × 10 ¹³ to 1 × 10 ¹⁸ Ω · cm, more preferably 5 × 10 ¹³ to 1 × 10 ¹⁸ Ω · cm. This is because if the volume resistivity is 1 × 10 ¹³ to 1 × 10 ¹⁸ Ω · cm, the electric insulation is satisfied. In addition, in this invention, volume resistivity means the value in 25 degreeC measured based on JIS-C2101 "electrical insulation oil test method" (2006). The volume resistivity of the composition for insulating oil and the insulating oil of the present invention is controlled within the range of 1 × 10 ¹³ to 1 × 10 ¹⁸ Ω · cm, for example, the composition for insulating oil and insulating oil This can be achieved by not containing ionic substances therein.

In the fatty acid ester composition for insulating oil of the present invention, the biodegradability test by OECD 301B increases the biodegradability by 60% in 28 days.

  The composition for insulating oil and insulating oil of the present invention has a hue of, for example, 2.5 or less, preferably 1.5 or less, more preferably 1.0 or less, and still more preferably 0.5 or less. This is because when the hue is 2.5 or less, deterioration due to oxidation or the like hardly occurs. In addition, in this invention, a hue means the value measured based on JIS-K2580 (2003). In addition, the color of the composition for insulating oil and the insulating oil of the present invention is controlled to 2.5 or less, for example, avoiding air mixing when synthesizing the ester, and further, the synthesized ester is activated carbon or activated. This can be achieved by refining with clay.

  Moreover, the composition for insulating oils of this invention is acid value (AV) from a viewpoint which suppresses corrosion of the remaining metal rather than a conventional thing like the composition for insulating oils of Example 1 mentioned later, for example. ) Is preferably low. Moreover, it is preferable that the composition for insulating oils of this invention has a low moisture content from a viewpoint of suppressing generation | occurrence | production of rust. In addition, the insulating oil composition of the present invention preferably has a low hydroxyl value (OHV) from the viewpoint of high thermal stability and suppression of hygroscopicity. Moreover, it is preferable that the composition for insulating oils of this invention has a moderately large saponification value (SV) from an electrical insulating viewpoint. Moreover, as for the composition for insulating oils of this invention, the iodine number of 70-160 is preferable from a viewpoint of reducing a pour point and improving oxidation stability.

  The ester of Example 1 can be obtained according to the production method. For example, the fatty acid ester of Example 1 was specifically produced under the following conditions.

(Production Example 1)
An ester was produced from a fatty acid composition (“Hartol FA-1”, manufactured by Harima Chemicals Co., Ltd.) and glycerin. Specifically, glycerin (330 g, 3.6 mol) and a fatty acid composition (“Hartol” were added to a 5-liter four-necked flask equipped with a stir bar, a nitrogen gas blowing tube, a thermometer and a water separator with a condenser. FA-1 ”, acid value 194, average molecular weight 289: 3574 g (12.4 mol)) (the carboxyl group of the fatty acid composition corresponds to 1.15 equivalents per 1 equivalent of the hydroxyl group of glycerin) at 25 ° C. Prepared.

  Next, heating was performed while blowing nitrogen gas (1 L / min) into the stirred flask, and the temperature of the reaction mixture in the flask was raised to 240 ° C. While maintaining at this temperature, water produced in the flask was removed using the moisture separator, and the reaction was allowed to proceed. The hydroxyl value of the reaction mixture in the flask was measured while the reaction proceeded, and the reaction was terminated when the hydroxyl value reached 1.9 mg KOH / g (after being maintained at 240 ° C. for 10 hours). Next, the remaining fatty acid composition was removed from the reaction mixture under reduced pressure (pressure was 0.001 kPa) while maintaining the temperature of the reaction mixture in the flask at 240 ° C. Thereafter, steam was introduced into the flask, and the fatty acid composition remaining from the reaction mixture was distilled off to obtain a crude ester. The acid value of this crude ester was 0.18 mg KOH / g. The crude ester was purified by activated carbon treatment and then acid adsorbent treatment to obtain a fatty acid ester (2984 g, yield 92%). Table 1 shows the composition of the fatty acid composition used as a raw material.

(Production Example 2)
Manufactured except that 3538 g (12.4 mol) of fatty acid composition (“SYLFAT 2LT”, Arizona Chemical Co., acid value 196) was used instead of fatty acid composition (“Hartol FA-1”, manufactured by Harima Chemical Co., Ltd.) In the same manner as in Example 1, 2923 g (yield 91%) of an ester of fatty acid was obtained. Table 1 shows the composition of the fatty acid composition used as a raw material.

(Production Example 3)
Instead of the fatty acid composition (“Hartol FA-1”, manufactured by Harima Kasei Co., Ltd.), 3630 g (12.4 mol) of the fatty acid composition (“Hartol FA-1P”, manufactured by Harima Chemical Co., Ltd., acid value 191) was used. Except for the above, in the same manner as in Production Example 1, 2898 g of fatty acid ester (yield 88%) was obtained. Table 1 shows the composition of the fatty acid composition used as a raw material.

(Production Example 4)
Instead of the fatty acid composition (“Hartol FA-1”, manufactured by Harima Chemical Co., Ltd.), 1685 g (5.8 mol) of “Hartol FA-1” (acid value 194 manufactured by Harima Chemical Co., Ltd.) was used. Except for the above, 2880 g of fatty acid ester (yield 90%) was obtained in the same manner as in Production Example 1. Table 1 shows the composition of the fatty acid composition used as a raw material.

[Examples 1 to 4]
The composition containing the fatty acid ester produced in Production Examples 1 to 4 was used as an insulating oil composition, and various physical properties were measured. The measuring method of the physical property is as follows. Table 2 shows the composition of the composition for insulating oil and the physical properties thereof.

[Measurement method of physical properties]
The kinematic viscosity at 40 ° C. and 100 ° C. is a kinematic viscosity measured based on JIS-K2283 (2000).

  The viscosity index is a viscosity index measured based on JIS-K 2283 (2000).

  The pour point is a pour point measured based on JIS-K2269 (1987).

  The flash point is a flash point measured based on JIS-K2265 (1996).

  The acid value (AV) is an acid value measured based on JIS-K2501 “Petroleum products and lubricants—neutralization test method” (2003).

  The water content is a content measured based on JIS-K2275 (1996).

  The hydroxyl value (OHV) is a hydroxyl value measured based on JIS-K0070 (1992).

  The saponification value (SV) is a saponification value measured based on JIS-K0070 (1992).

  The iodine value is an iodine value measured based on JIS-K0070 (1992).

  The volume resistivity is a value at 25 ° C. measured based on JIS-C2101 “Electrical insulating oil test method” (2006).

  The density at 25 ° C. or 15 ° C. is a value measured at 25 ° C. or 15 ° C. based on JIS-K2249 (1995).

  The hue is a value measured based on JIS-K2580 (2003).

  The cloud point is a value measured based on JIS-K2269 (1987).

(Comparative Example 1)
A fatty acid composition in which saturated fatty acids were further removed from fatty acids obtained from soybean oil was prepared. This fatty acid composition and glycerin can be reacted according to the method described in Example 1 to obtain an ester composition. This ester composition is used as an insulating oil composition, and Table 2 shows the composition of the insulating oil composition and its physical properties.

(Comparative Example 2)
Table 2 shows the composition of rapeseed oil (rapeseed white squeezed oil) and its physical properties.

(Comparative Example 3)
Table 2 shows the composition of mineral oil and its physical properties. These data are based on “Abstracts of 25th Insulating Oil Subcommittee Meeting” (The Japan Petroleum Institute, Kyoto City Kyogyokan, pages 41-45).

  In the fatty acid used in Example 1, when the total fatty acid is 100% by weight, the contents of fatty acid A, fatty acid B, and resin acid are 46.0% by weight, 39.3% by weight, and 1% by weight, respectively. is there. The total of fatty acid A and fatty acid B and the resin acid content are 85.3% by weight and 1% by weight, respectively, when the total fatty acid is 100% by weight. Moreover, when making the whole fatty acid into 100 weight%, the total amount of the fatty acid A, the fatty acid B, and the resin acid is 86.3% by weight.

  In the fatty acid used in Example 2, when the total fatty acid is 100% by weight, the contents of fatty acid A, fatty acid B, and resin acid are 31.3% by weight, 45.2% by weight, and 1.9% by weight, respectively. %. The total of fatty acid A and fatty acid B and the resin acid content are 76.5% by weight and 1.9% by weight, respectively, when the total fatty acid is 100% by weight. Moreover, when making the whole fatty acid into 100 weight%, the total amount of the fatty acid A, the fatty acid B, and the resin acid is 78.4 weight%.

  In the fatty acid used in Example 3, when the total fatty acid is 100% by weight, the contents of fatty acid A, fatty acid B, and resin acid are 38.7% by weight, 33.3% by weight, and 4.3% by weight, respectively. %. The total of fatty acid A and fatty acid B and the resin acid content are 72% by weight and 4.3% by weight, respectively, when the total fatty acid is 100% by weight. When the total fatty acid is 100% by weight, the total amount of fatty acid A, fatty acid B and resin acid is 76.3% by weight.

  In the fatty acid used in Example 4, when the total fatty acid is 100% by weight, the contents of fatty acid A, fatty acid B, and resin acid are 59.2% by weight, 22.0% by weight, and 0.5% by weight, respectively. %. Further, the total of fatty acid A and fatty acid B and the content of the resin acid are 81.2 wt% and 0.5 wt%, respectively, when the total fatty acid is 100 wt%. Moreover, when making the whole fatty acid into 100 weight%, the total amount of the fatty acid A, the fatty acid B, and the resin acid is 81.7 weight%.

  In the insulating oil composition of Example 1, when the total fatty acid ester is 100% by weight, the contents of fatty acid A ester, fatty acid B ester, and resin acid ester are 45% by weight and 39% by weight, respectively. And 1% by weight. Further, the total of the fatty acid A ester and the fatty acid B ester and the resin acid ester content are 84 wt% and 1 wt%, respectively, when the total fatty acid ester is 100 wt%. When the total fatty acid ester is 100% by weight, the total amount of the fatty acid A ester, the fatty acid B ester, and the resin acid ester is 85% by weight.

  In the insulating oil composition of Example 2, when the total fatty acid ester is 100% by weight, the contents of the fatty acid A ester, the fatty acid B ester, and the resin acid ester are 31.3% by weight and 45%, respectively. .2% by weight and 1.9% by weight. Further, the total of the fatty acid A ester and the fatty acid B ester and the resin acid ester content are 76.5 wt% and 1.9 wt%, respectively, when the total fatty acid ester is 100 wt%. When the total fatty acid ester is 100% by weight, the total amount of the fatty acid A ester, the fatty acid B ester, and the resin acid ester is 78.4% by weight.

  In the insulating oil composition of Example 3, when the total fatty acid ester is 100% by weight, the contents of fatty acid A ester, fatty acid B ester, and resin acid ester are 40.9% by weight and 35%, respectively. 0.5 wt% and 4.3 wt%. The total of fatty acid ester A and fatty acid B ester and resin acid ester content are 76.4% by weight and 4.3% by weight, respectively, when the total fatty acid ester is 100% by weight. When the total fatty acid ester is 100% by weight, the total amount of the fatty acid A ester, the fatty acid B ester, and the resin acid ester is 80.7% by weight.

  In the composition for insulating oil of Example 4, when the total fatty acid ester is 100% by weight, the contents of fatty acid A ester, fatty acid B ester, and resin acid ester are 59.8% by weight and 22%, respectively. .2 wt% and 0.5 wt%. The total of fatty acid A ester and fatty acid B ester and resin acid ester content are 82% by weight and 0.5% by weight, respectively, when the total fatty acid ester is 100% by weight. When the total fatty acid ester is 100% by weight, the total amount of the fatty acid A ester, the fatty acid B ester, and the resin acid ester is 82.5% by weight.

  As shown in Tables 1 and 2, from the results of Examples 1 to 4 and Comparative Examples 1 to 3, it was confirmed that the composition for insulating oil of the present invention had a lower pour point than the conventional one. . Therefore, the composition for insulating oil of the present invention is also suitable for use in cold regions. Moreover, it has confirmed that the composition for insulating oils of this invention was a flash point equivalent to a conventional one. Therefore, the composition for insulating oil of the present invention is flame retardant and suitable for use as insulating oil.

  Moreover, the composition for insulating oils of this invention has confirmed that an acid value (AV) was lower than the conventional one. Therefore, the composition for insulating oil of the present invention is stable and can suppress the decay of the remaining metal.

  The composition for an insulating oil and the fatty acid composition of the present invention are useful, for example, as an insulating oil or for producing a composition for an insulating oil or an insulating oil.

Claims (7)

An insulating oil composition comprising an ester of fatty acid,
In 100% by weight of the fatty acid ester,
Ester of monoene unsaturated fatty acid having 18 carbon atoms (hereinafter referred to as fatty acid A),
An ester of a diene unsaturated fatty acid having 18 carbon atoms (hereinafter referred to as fatty acid B), and
The total amount of esters of resin acid is 75% by weight or more, and
When the total fatty acid ester is 100% by weight, the fatty acid A ester, the fatty acid B ester, and the resin acid ester content are 25 to 70% by weight, 20 to 60% by weight, and The composition for insulating oils which is 0.1 to 15 weight%. When the total amount of the fatty acid ester is 100% by weight, the total of the fatty acid A ester and the fatty acid B ester and the resin acid ester content are 65 to 95% by weight and 0.1%, respectively. The composition for insulating oil according to claim 1, which is ˜15 wt%.   The composition for insulating oil according to claim 1, wherein the fatty acid A, the fatty acid B, and the resin acid are derived from tall oil fatty acid. The ester of the fatty acid A, the ester of the fatty acid B, and the ester of the resin acid are esters obtained from the fatty acid A, the fatty acid B, and the resin acid and alcohol, respectively.
The composition for insulating oil according to claim 1, wherein the alcohol is an aliphatic alcohol having 1 to 6 hydroxy groups.   The composition for insulating oil according to claim 4, wherein the aliphatic alcohol is one or more selected from the group consisting of trimethylolpropane, pentaerythritol, trimethylolethane, trimethylolbutane, neopentylglycol and glycerin. An insulating oil containing an ester of fatty acid,
In 100% by weight of the fatty acid ester,
Ester of monoene unsaturated fatty acid having 18 carbon atoms (hereinafter referred to as fatty acid A),
An ester of a diene unsaturated fatty acid having 18 carbon atoms (hereinafter referred to as fatty acid B), and
The total amount of esters of resin acid is 75% by weight or more, and
When the total fatty acid ester is 100% by weight, the fatty acid A ester, the fatty acid B ester, and the resin acid ester content are 25 to 70% by weight, 20 to 60% by weight, and Insulating oil which is 0.1 to 15% by weight. A fatty acid composition used for production of an insulating oil composition containing an ester of fatty acid,
In 100% by weight of the fatty acid in the fatty acid composition,
C18 monoene unsaturated fatty acid (hereinafter referred to as fatty acid A),
The total amount of diene unsaturated fatty acid having 18 carbon atoms (hereinafter referred to as fatty acid B) and resin acid is 75% by weight or more, and
When the total amount of the fatty acid is 100% by weight, the content ratios of the fatty acid A, the fatty acid B, and the resin acid are 25 to 70% by weight, 20 to 60% by weight, and 0.1 to 15% by weight, respectively. A fatty acid composition.