JP2009076288A - Electric insulating oil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide electric insulating oil reducing environmental loads, having solid state properties of lower viscosity and current point than those of vegetable oil, and electric properties equivalent to vegetable oil. <P>SOLUTION: A polyglycerine fatty acid ester made from a 8-20C fatty acid and polyglycerine having a mean polymerization grade of 2 to 10 has a characteristic as an electric insulating oil excelling in solid state properties such as viscosity, current point, flash point, etc. By being produced from plant-derived materials, the electric insulating oil has solid state properties of lower viscosity and current point than those of vegetable oil, and electric properties equivalent to vegetable oil, and is capable of reducing more environmental load than petroleum or synthetic insulating oil. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrical insulating oil, and more particularly to an insulating oil with reduced environmental load and improved physical properties such as kinematic viscosity and pour point.

Insulating oils used for insulation and cooling of transformers, cables, circuit breakers, condensers, etc. have been used in the past for natural vegetable oils such as soybean oil, rapeseed oil and castor oil. Oil-based insulating oils fractionated and refined from crude oil, hydrocarbon-based oils such as alkylbenzene, chlorinated hydrocarbon-based oils such as diphenyl chloride, synthetic insulating oils such as ester-based oils, silicone oils, etc. became.
However, when considering petroleum-related insulating oils for disaster prevention such as low flash point and environmental issues in recent years, from the viewpoint of reducing carbon dioxide emissions in global warming prevention measures, in terms of carbon neutral, It is not preferable for the global environment.
Synthetic insulating oils have problems in safety and environmental pollution, such as suspicion of endocrine disrupting action in phthalates and toxicity of PCBs.
From these circumstances, if vegetable oils with excellent safety can be reused as electrical insulating oils, the above problems of petroleum-based and synthetic insulating oils can be solved. However, vegetable oils have high viscosity and pour points. It has the problem of being expensive.
In order to solve the above problems of vegetable oils, proposals have been made to use lower alcohol esterified natural vegetable oils as electrical insulating oils (see, for example, Patent Documents 1, 2, 3, and 4).
However, these insulating oils can achieve a low viscosity, but they are not satisfactory in terms of physical properties because of their low flash point and high pour point.
Examples of the compound having a chemical structure similar to that of vegetable oil include polyglycerol fatty acid esters. Polyglycerin fatty acid ester can prepare various properties of compounds from solid to liquid at room temperature by selecting fatty acid and polyglycerin constituting the molecule, and it can be used as electrical insulating oil, No proposal has been made to use polyglycerol fatty acid esters as electrical insulating oils.
Japanese Patent Laid-Open No. 9-259638 Japanese Patent Laid-Open No. 11-306864 JP 2000-90740 A WO2005 / 022558

  The problem to be solved by the present invention is to provide an electrical insulating oil that has reduced environmental impact, has lower viscosity and lower pour point properties than vegetable oil, and has electrical properties equivalent to vegetable oil.

As a result of intensive studies to solve the above problems, the present inventors have found that an esterified product of a fatty acid having 8 to 20 carbon atoms and a polyglycerin having an average polymerization degree of 2 to 10 has viscosity, pour point, flash point, etc. It is excellent in the physical properties of the present invention and has reached the above object of the present invention.
That is, the present invention has the following configuration.
1. An electrical insulating oil comprising a polyglycerol fatty acid ester composed of a fatty acid having 8 to 20 carbon atoms and a polyglycerol having an average polymerization degree of 2 to 10.
2. 2. The electrical insulating oil as described in 1 above, wherein the fatty acid is caprylic acid and / or capric acid.
3. 3. The electrical insulating oil according to 1 or 2, wherein the polyglycerin has an average degree of polymerization of 2.
4). An electrically insulating oil comprising 50 to 100% by mass of the polyglycerin fatty acid ester according to 1, 2 or 3, and 0 to 50% by mass of vegetable oil and / or medium chain fatty acid triglyceride.

  According to the present invention, it has lower viscosity and lower pour point properties than vegetable oils, has electrical properties equivalent to vegetable oils, and is composed of plant-derived raw materials, thereby reducing environmental burden compared to petroleum-based and synthetic insulating oils. Electric insulating oil that can be reduced can be provided.

Hereinafter, the present invention will be described in detail according to the best mode for carrying out the invention.
The fatty acid constituting the polyglycerol fatty acid ester used in the present invention has 8 to 22 carbon atoms, for example, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, erucic acid , Palmitoleic acid, oleic acid, linoleic acid, linolenic acid, isostearic acid, and the like. One of these or a mixture of these in any ratio can be used. Moreover, it is preferable that the raw material origin of these fatty acids is animal and vegetable oils.

  The polyglycerin constituting the polyglycerin fatty acid ester used in the present invention is known to have an average polymerization degree of 2 to 100 as a polymer of glycerin. From the viewpoint of safety to human body and environment, the average polymerization degree The thing of 2-10 is preferable. More preferably, the starting material is animal or vegetable oil.

  The polyglycerol fatty acid ester used in the present invention can be produced by using various known esterification methods using the above fatty acid and polyglycerol as raw materials. For example, polyglycerin and fatty acid are charged in a ratio of (number of moles of carboxyl group of fatty acid) / (number of moles of hydroxyl group of polyglycerin) = 1.05 to 1.3, using no catalyst, alkali catalyst or acid catalyst. In an inert gas atmosphere, a normal pressure or reduced pressure reaction is performed at 200 ° C. to 250 ° C. for 5 to 20 hours, and excess fatty acid is distilled off under reduced pressure or steam distillation. At this time, the quality of the produced polyglycerin fatty acid ester has an acid value of 1 or less, preferably 0.1 or less, and a hydroxyl value of 10 or less, preferably 5 or less. If the acid value is greater than 1 or the hydroxyl value is greater than 10, the electrical properties of the polyglycerol fatty acid ester are deteriorated.

  In addition, the polyglycerin fatty acid ester of the present invention contains a small amount of free fatty acid and impurities contained in the ester using an inorganic synthetic adsorbent such as activated clay and activated alumina and an adsorbent such as activated carbon after the esterification reaction. It is preferable to remove by adsorption. Furthermore, it is preferable to perform a deaeration process under vacuum to remove air and moisture.

  Moreover, the electrical insulation oil of this invention can mix and use the said polyglyceryl fatty acid ester, vegetable oil, and / or medium chain fatty acid triglyceride. The mixing ratio of the vegetable oil and / or medium chain fatty acid triglyceride to the total amount of the electrical insulating oil is 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less. Mixing vegetable oils is effective in increasing the flash point, but if the mixing ratio with respect to the total amount of the electrical insulating oil exceeds 50% by mass, the pour point becomes too high, which is not preferable. Mixing of medium-chain fatty acid triglycerides is effective in reducing the viscosity, but if the mixing ratio with respect to the total amount of the electric insulating oil exceeds 50% by mass, the flash point is undesirably reduced.

  Examples of the vegetable oil include soybean oil, rapeseed oil, castor oil, corn oil, safflower oil, sunflower oil, and the like. ) Glycerides can be mentioned.

  The electrical insulating oil of the present invention can be used alone, but an additive such as an antioxidant, a pour point depressant, a fluid antistatic agent and the like is blended in the range without impairing the effects of the invention. Can be used.

  There is no restriction | limiting in particular in the application object of the electrical insulation oil of this invention, It can apply to the electric equipment conventionally used for electrical insulation oil, for example, a transformer, a cable, a circuit breaker, a capacitor | condenser etc.

  Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Examples 1-3, Comparative Examples 1-2
Electrical insulating oils A to C were prepared by the following synthesis method, and physical properties and electrical characteristics were evaluated. Moreover, the same evaluation was performed about rapeseed white squeezed oil and tricaprylic acid glyceride as a comparative example. Table 1 shows the physical properties and electrical characteristics.
In addition, the analysis of the sample used for the test, the physical property, and the evaluation method of an electrical property were performed based on the following test methods.
Total acid value: JIS C 2101
Hydroxyl value: The Oil Chemical Society of Japan (2.3.6-1996)
Moisture: JIS C 2101 (Karl Fischer type volumetric titration method)
Kinematic viscosity: ASTM D7042
Pour point: ASTM D6749
Flash point: JIS K 2265 (Cleveland open type)
Dielectric breakdown voltage: JIS C 2101
Volume resistivity: JIS C 2101
Dielectric loss tangent: JIS C 2101

<Creation of electrical insulating oil A>
325 g of diglycerin (Diglycerin S: Sakamoto Yakuhin Kogyo Co., Ltd.) and 1276 g of caprylic acid (NAA-82: Nippon Oil & Fats Co., Ltd., hereinafter the same) are charged into a four-necked flask and stirred under nitrogen gas. The reaction was carried out at 230 ° C. for 8 hours while blowing. Next, under reduced pressure of 1.5 kPa, unreacted fatty acid was distilled off while blowing water vapor to obtain diglycerin caprylate.
2 parts by mass of an inorganic adsorbent (KYOWARD 500SH: manufactured by Kyowa Chemical Industry Co., Ltd.) is added to 100 parts by mass of the diglycerin caprylate, and after an adsorption treatment at 120 ° C. for 1 hour, the inorganic adsorbent is filtered. Was removed. Furthermore, the deaeration process was performed at 120 degreeC under pressure reduction of 1.5 kPa for 1 hour, and the electrically insulating oil A was obtained.
The resulting electrical insulating oil A had a total acid value of 0.07, a hydroxyl value of 0.4, and a moisture content of 92 ppm.
<Creation of electrical insulating oil B>
Decaglycerin (polyglycerin # 750: manufactured by Sakamoto Pharmaceutical Co., Ltd.) 558 g and caprylic acid (NAA-82: manufactured by Nippon Oil & Fats Co., Ltd., the same shall apply hereinafter) 1328 g were charged into a four-necked flask and stirred under nitrogen. The reaction was carried out at 230 ° C. for 8 hours while blowing gas. Next, unreacted fatty acid was distilled off under reduced pressure of 1.5 kPa while blowing water vapor to obtain decaglycerin caprylate.
2 parts by mass of an inorganic adsorbent (KYOWARD 500SH: manufactured by Kyowa Chemical Industry Co., Ltd.) is added to 100 parts by mass of this decaglycerin caprylate, and after an adsorption treatment at 120 ° C. for 1 hour, the inorganic adsorbent is filtered. Was removed. Furthermore, deaeration treatment was performed at 120 ° C. for 1 hour under a reduced pressure of 1.5 kPa to obtain an electric insulating oil B.
The obtained electrical insulating oil B had a total acid value of 0.09, a hydroxyl value of 2.2, and a moisture content of 123 ppm.
<Creation of electrical insulating oil C>
960 g of the above electric insulating oil A and 640 g of tri (caprylic acid / capric acid) glyceride (Actor M-1: manufactured by Riken Vitamin Co., Ltd.) are charged into a four-necked flask and stirred at 80 ° C. for 30 minutes while blowing nitrogen gas. As a result, an electric insulating oil C was obtained.
The obtained electrical insulating oil C had a total acid value of 0.07, a hydroxyl value of 0.4, and a water content of 88 ppm.

表１の結果から明らかな通り、本発明の電気絶縁油、特に電気絶縁油A及びCは菜種油や中鎖脂肪酸トリグリセライドとほぼ同等の電気特性を有し且つ、菜種油より低粘度、低流動点を実現している。また、引火点が２５０℃以上であり防災上の安全性も向上している。

As is apparent from the results in Table 1, the electrical insulating oils of the present invention, especially the electrical insulating oils A and C, have almost the same electrical characteristics as rapeseed oil and medium-chain fatty acid triglycerides, and have a lower viscosity and lower pour point than rapeseed oil. Realized. In addition, the flash point is 250 ° C. or higher, and safety for disaster prevention is also improved.

  The present invention has an electrical property equivalent to that of vegetable oil while having a lower viscosity and a lower pour point than vegetable oil, and has an environmental impact reduced compared to petroleum-based or synthetic insulating oil by being manufactured from plant-derived raw materials. Insulating oil can be provided, and the present invention can be applied to electrical devices that are conventionally known to use electrical insulating oil, such as transformers, cables, circuit breakers, and capacitors.

Claims (4)

  An electrical insulating oil comprising a polyglycerol fatty acid ester composed of a fatty acid having 8 to 20 carbon atoms and a polyglycerol having an average polymerization degree of 2 to 10.   2. The electrical insulating oil according to claim 1, wherein the fatty acid is caprylic acid and / or capric acid.   The electrical insulating oil according to claim 1 or 2, wherein the average degree of polymerization of the polyglycerin is 2.   An electrically insulating oil comprising 50 to 100% by mass of the polyglycerol fatty acid ester according to claim 1, 2 or 3, and 0 to 50% by mass of vegetable oil and / or medium chain fatty acid triglyceride.