JPS606044B2 - Electrical insulation oil composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an oxidatively stable and thermally stable electrically insulating base oil obtained by adding an essentially amorphous ethylene-propylene copolymer to an electrically insulating base oil derived from a paraffinic base crude oil or a mixed base crude oil. , relates to an electrical insulating oil composition with excellent corona resistance, corrosion resistance, and low-temperature performance.

More specifically, (1) paraffin base crude oil or mixed base crude oil is distilled at atmospheric pressure, or residual oil from atmospheric distillation is distilled under reduced pressure to obtain a boiling point (converted to normal pressure) in the temperature range of 230 to 430 qo. Raffinate obtained by solvent refining distillate oil containing crab content of 8 K% or more is further hydrorefined, subjected to solvent dewaxing treatment, and if necessary, further solid adsorbent treatment. Refined oil with a sulfur content of 0.25 wt% or less 5 to 9 t% (0) Refined oil obtained by treating the lubricating oil fraction of mineral oil with a solid adsorbent 1 to 2 t% (m) 9 books are mixed at a ratio of t%, and the total Io content is 0.3
Electrical insulating base oil with a weight average molecular weight of 10,000 to 200,000 and a propylene content of 1 to 5 wt% or less (W)
0 to 70 mol% of an essentially amorphous ethylene-propylene copolymer to the electrical insulating oil base oil.
~1. The present invention relates to an electrical insulating oil composition with excellent oxidation stability, thermal stability, corona resistance, corrosion resistance, and low temperature performance, which is obtained by adding 5% by weight.

Today, various types of insulating oils are on the market, but the majority of them in terms of quantity are key oil-based insulating oils.

The reason for this is that compared to insulating oils obtained by synthetic methods, chick oil-based insulating oils use petroleum fractions as the main raw material and can therefore be supplied in large quantities at relatively low costs. However, this key oil-based insulating oil is by no means a product that can be produced from any crude oil without much difference, such as gasoline or kerosene.

In fact, the selection of crude oil is most important in producing key oil-based insulating oil. That is, there is a practical need for a naphthenic crude oil whose specific gravity, flash point, and viscosity are within certain ranges, and which usually has a low freezing point and low sulfur content. Many methods for producing tin oil-based electrical insulating oils are known, but conventional electrical insulating oils actually use naphthene-based crude oil as the raw material, and electrical insulating oils are produced from paraffin-based crude oil or mixed base crude oil. When producing electrical insulating oil using conventional methods for producing electrical insulating oil from naphthenic crude oil, it is not possible to obtain electrical insulating oil with satisfactory properties.

The following methods are known as conventional methods for producing electrical insulating oil from naphthenic crude oil. There is a method of producing insulating oil by carrying out sulfuric acid treatment using a specific and limited method (for example, Japanese Patent Publication No. 10133/1983). However, the method of sulfuric acid treatment is not only inconvenient because disposal of the by-product waste sulfuric acid pollutes the environment, but also has a low product yield and is not industrially practical. It is also known to use key oil that has been hydrodesulfurized to 65 to 96%, or to mix this with mineral oil having a lower aromatic content. However, in this case, it is stated that if the mineral oil is treated with a solvent before hydrodesulfurization, the oxidation stability etc. will be extremely poor (Samurai Kosho 36-118584). In addition, similar to this method, 9 lubricating oil fractions without solvent refining are used.
There is also a method of hydrorefining to desulfurize 5% or more and adding mineral oil treated with sulfuric acid to this (Japanese Patent Laid-Open No. 49-46199).
.

It is also known that a lubricating oil raffinate with an aromatic content of 23 wt% or less is hydrogenated, and a lubricating oil with a higher aromatic content of 15 wt% or less is added thereto (
Special Publication No. 41-3589).

As such, the method using these naphthenic crude oils discloses a method for producing an insulating oil. However, since the recent so-called oil crisis, it has become extremely difficult to obtain this naphthenic crude oil, and it is expected to obtain insulating oil from mixed base crude oil or paraffin base crude oil, which are relatively inexpensive and available in large quantities. However, when obtaining insulating oil from these mixed base crude oils or paraffin base crude oils, the oxidation stability, hydrogen gas absorption, corona resistance, pour point, etc. can be satisfied even if the production method from naphthenic base crude oils is applied as is. If you cannot obtain something, you will need to use a special and limited method. On the other hand, in recent years, as a method for producing insulating oil from paraffin-based crude oil, a method has been disclosed in which insulating oil with a low pour point is obtained by distillation after dewaxing treatment (
Special Publication No. 49-46123). However, in this method, refined oil having an aromatic content of about 14% at most is used, and a product insulating oil is obtained by adding an antioxidant. On the other hand, recently, small and medium-sized transformers are becoming more compact and lighter in weight, and therefore 65qorise transformers are being designed, which are 10 times higher than conventional operating temperatures, and can withstand such temperatures. Insulating materials are now required.

Conventional high quality paper and naphthenic key oil alone do not have a sufficient lifespan under these conditions. In addition, in recent years, capacitors, not only cables but also transformers and circuit breakers, are sufficiently degassed when filling with oil, and even after filling, measures such as diaphragm type or nitrogen filling are taken, so the presence of oxygen is extremely rare. Therefore, in addition to oxidation stability, which has traditionally been emphasized, the quality of oil can be evaluated based on changes in electrical properties during thermal deterioration.In other words, insulating oil with excellent thermal stability is widely desired. In order to satisfy all of the main properties of insulating oils, such as oxidation stability, thermal stability, corona resistance, and corrosion resistance, the present inventors have developed a paraffin-based crude oil or a mixture that is available in relatively large quantities. As a result of intensive research into the refining conditions for base crude oil, we discovered a method that could stably produce superior electrical insulating oil, which was different from conventional methods, and filed a patent application
4y).

The present invention is characterized by adding a small amount of an essentially amorphous ethylene-propylene copolymer to the electrical insulating oil base oil obtained from paraffin base crude oil or mixed base crude oil by the above-mentioned specific method, thereby eliminating any loss in other properties. This invention relates to an electrical insulating oil composition that has significantly improved low-temperature performance without any problems.

The present invention will be explained in more detail below.

First, the first component forming the basis of the insulating oil of the present invention will be described.

The paraffin-based crude oil referred to in the present invention is usually crude oil containing a large amount of paraffinic hydrocarbons, and is referred to in "Petroleum Handbook" 19.
As stated on page 19 of the 72 King Edition (published by Sekiyu Shunjusha), the API gravity of the first key fraction of crude oil (kerosene fraction) is 4.
0o or higher, and the API specific gravity of the second key fraction (275-300℃/4-day lubricating oil fraction) is 300 or higher. Typical examples include Pennsylvania crude oil, Minas crude oil, etc. It is.

Mixed base crude oil is usually intermediate between paraffin base crude oil and naphthene base crude oil, and the API gravity of the first key fraction is 33 to 40o, and the API gravity of the second key fraction is 20 to 3.
00 and is often found in Middle Eastern crude oils such as Midcontinent crude oil, Arabian crude oil, and Khafji crude oil. In the present invention, Arabian crude oils such as Arabian medium and Arabian light are preferably used. The electrical insulating oil base oil used in the present invention consists of a mixed oil of refined oil (1) as the first component, refined oil (0) as the second component, and aryl alkane (m) as the third component. .

First, refined oil (m) is obtained as follows.

Boiling point (converted to normal pressure) of paraffin base crude oil or mixed base crude oil obtained by distilling residual Gulf oil under atmospheric pressure from 230 to 430°C
A distillate oil containing about 8 skin t % or more, preferably 9 skin t % or more of a fraction falling within a temperature range of 250 to 400 qo is treated with a solvent that selectively dissolves aromatic compounds. The solvent used here that selectively dissolves aromatic compounds is commonly used, and specifically, furfural, liquid sulfur dioxide, phenol, etc. are used.

In the present invention, furfural is particularly suitable, and when furfural is used, the extraction temperature is usually 50 to 100o.
o Preferably 60-9000, the ratio (volume ratio) of furfural to key oil is 0.3-2. Government is preferably 0.5
~1.5. Next, the raffinate obtained by solvent refining is hydrorefined and subjected to solvent dewaxing treatment in order to lower the pour point. Further, if necessary, a solid adsorbent treatment is subsequently performed to obtain refined oil (1), which is the first component. Among these processing steps, the conditions for solvent refining and hydrorefining are such that the sulfur content of refined oil (1) is reduced to 0.25w.
t% or less. Here, refined oil (1
) is set to 0.25 wt% or less in order not to have an adverse effect on the copper blackening phenomenon inside transformers, which has recently become a problem. The catalyst used for hydrorefining in the present invention is a carrier of bauxite, activated carbon, Fuller's carbon, diatomaceous earth, zeolite, alumina, silica, silica alumina, etc. A metal oxide that is usually pre-sulfurized before use.
Specific examples of these oxides include cobalt oxide, molybdenum oxide, tungsten oxide, and nickel oxide. In the present invention, a presulfurized catalyst consisting of nickel oxide and molybdenum oxide supported on an aminium oxide-containing carrier is particularly preferably used. The reaction temperature in the hydrorefining treatment of the present invention is usually 230 to about 100°C, preferably 260 to 320°C. At low temperatures, the reaction rate is low, and at high temperatures, the paraffin content increases due to decomposition, slightly raising the pour point, and the color of the product is also unfavorable. The reaction pressure is 25k9'G or more,
Preferably from 25 to 75 kg'G, most preferably from 35 to 75 kg'
45 kg/○. In addition, hydrogen is 100 to 1000, preferably 200 to
Make contact within the range of 100 side. In the hydrorefining in the present invention, a method that further suppresses hydrocracking is adopted. Solvent dewaxing in the present invention involves solidifying and removing the wax content in the oil by a known method, and the commonly used method is the BK method.

The solvent used is a mixed solvent such as benzene-toluene-acetone or benzene-toluene-methyl ethyl ketone. As for the composition of the solvent (ratio of ketone content and aromatic content), a suitable mixing ratio is 30 to 35% in the case of acetone, and 45 to 50% in the case of methyl ethyl ketone. The solvent ratio can be determined by adding solvent so that the viscosity of the solution fed to the dewaxing filter is approximately constant. The solvent dewaxing treatment in the present invention may be carried out at any stage, but it is particularly preferably carried out after hydrorefining. Continue to perform solid adsorbent treatment if necessary.
The solid adsorbent treatment mentioned here refers to acid clay, activated clay,
A process in which a solid adsorbent such as Fuller's earth, alumina, or silica alumina is brought into contact with key oil. Usually about 50-80qo
Let it touch the bush for about 30 minutes to several hours. The contact method may be a percolation method or a contact method. On the other hand, the refined oil used as the refined oil (0), which is the second component of the present invention, is obtained by distilling various crude oils and usually has a boiling point of about 230~230.
Approximately 8 crabs are included in the temperature range of 460℃ (converted to normal pressure).
A lubricating oil fraction containing t% or more of the skin is treated with a solid adsorbent.

In the solid adsorbent treatment referred to herein, the same conditions as those employed in the case of the first component described above are employed. In the present invention, if the key oil as the second component is not treated with a solid adsorbent, the properties of the insulating oil, such as electrical properties, hue, and thermal stability, will be inferior. The second component of the present invention can be carried out singly or in combination with a solvent purification treatment, a dewaxing treatment, a sulfuric acid purification treatment, etc. before the solid adsorbent treatment.

The solvent refining treatment and the solvent dewaxing treatment mentioned here are treatments similar to those that can be employed for the first component described above.

In addition, for sulfuric acid refining treatment, the same conditions as those for sulfuric acid treatment of mineral oil are usually adopted, but since waste sulfuric acid is discharged, preferably other refining means described above are adopted.The sulfur content of the second component is preferably about 1.0 to approximately 1.0%, more preferably 0.0%.
It is 2 to lwt%. In this application, as mentioned above,
If the solid adsorbent treatment is also performed when obtaining the first component, the solid adsorbent treatment may be performed at the same time after mixing the hydrorefined dewaxed oil for the first component and the lubricating oil fraction for the second component. can.

When the amount of the second component is less than 1 part by weight, corrosion resistance, corona resistance, and thermal stability are good, but oxidation stability is insufficient.

Furthermore, if the amount of the second component is more than 20 parts by weight, corrosion resistance and thermal stability will be poor. Further, the aryl alkane (m) which is the third component of the present invention is as follows. That is,
It is an alkylbenzene represented by the following general formula: ``In the formula, R,, R2 is hydrogen or a hydrocarbon residue having 1 to 20 carbon atoms, and the total number of carbon atoms of R, and R2 is 9 or more, preferably 1.
2 to 28. If the total number of carbon atoms is less than 9,
It is inconvenient because the flash point and evaporation test properties deteriorate.
The hydrocarbon residue of R, 9 R2 may be either linear or branched. These alkylbenzenes may also contain up to about 5% by weight of tetralin, indene, or their hydrocarbon derivatives. It is obtained by condensing (alkylating) these compounds in the presence of an acid catalyst such as a Friedel-Krach type catalyst.

Industrially, monoalkylbenzenes having about 9 to 16 carbon atoms obtained when synthesizing linear or branched alkylbenzenes for detergents, heavy alkylbenzenes produced by-product when synthesizing these, and pot residue (for detergents) are used industrially. Residue oil from which alkylbenzene has been removed by distillation) is preferably used. These aryl alkanes are preferably treated with a solid adsorbent. In this case, the third component, which has not been treated with a solid adsorbent, is mixed with either the hydrotreated dewaxed oil for the first component, the lubricating oil fraction for the second component, or both, and then the solid adsorbent treatment is performed at the same time. can be done. Also~
These aryl alkanes are generally preferably used after hydrogenation treatment in terms of electrical properties and the like. In this case, the catalyst used in the hydrogenation treatment includes one or more metals, metal oxides, and metal sulfides from groups, skin groups, and blood groups of the periodic table, and solids such as silica, alumina, diatomaceous material, and activated carbon. Those pressed onto a carrier are preferably used. Specifically, catalysts such as palladium, platinum, nickel, copper-chromium, cobalt-molybdenum, nickel-molybdenum, and nickel-tungsten supported or not supported on the above-mentioned carriers can be preferably applied. The hydrogenation reaction conditions are:
Pressure: Normally 2-50k9'G, temperature 50-400k9'
, liquid space velocity 1-15 yol. 'Vol. It will be held in When using linear alkylbenzene with a boiling point of approximately 300°C or higher as the aryl alkane, hydrogenation is performed under conditions that selectively hydrogenate only the alkyl polycyclic aromatics contained as impurities, and the wavelength in the visible region is The absorbance at 400m is 0.

4×10-3 times.

It is particularly preferable to use it as below. In the present invention, these three components described above are used as the first component 5 to
9 skin t% and preferably 30 to 8% of the second component 1 to 2
Mix in a range of skin t%~preferably 2~1% and 5~9% of the third component~total amount of 0.

The content shall be 35 wt% or less.

If the amount of the third component aryl alkane added is less than 5 wt%, properties such as thermal stability and corona resistance will not be sufficient, and if the amount added is more than 90%, these properties will be further improved. Not only is it rare, but it is also expensive and uneconomical. It is usually used in a range of 10 to 5%. Furthermore, ``The present invention requires that the total sulfur content after mixing the three components be 0.35 M% or less.

When the sulfur content is more than 0.35 wt%, corrosion resistance (
The steel's blackening resistance deteriorates, and it cannot be put to practical use effectively. In the present invention, the total sulfur content is preferably about 0.05
~0.3 Wt%. The present invention further improves low-temperature properties by adding an essentially amorphous ethylene-propylene copolymer to an electrically insulating oil base oil obtained from a paraffin base crude oil or a mixed base crude oil by a specific method as described above. It is an object of the present invention to provide an even better electrical insulating oil composition.

The electrical insulating base oil in the present invention can have its pour point lowered by solvent dewaxing treatment as described above, but the pour point is J
Pass the IS standard (JIS-2320) -27.5q
This is almost the limit for ordinary dewaxing equipment to lower the pour point to 125° C., and in consideration of economic efficiency, dewaxing treatment with a pour point of about 125° C. or higher is desirable.

The present invention improves the above drawbacks and lowers the pour point easily and more economically without carrying out solvent dewaxing treatment under severe conditions. In other words, the present invention allows electrical insulating oil base oil that has been subjected to solvent dewaxing treatment under mild conditions to be easily and economically dewaxed by adding a small amount of an essentially intangible ethylene-propylene copolymer. 27
．． It is characterized in that it produces a final product with a very low pour point of 5 qo or less, or -40 qo or less, which cannot be reached by ordinary melt dewaxing treatment. Most of the pour point depressants conventionally widely used in lubricating oils are polymethacrylates.

However, although this additive exhibits an excellent pour point lowering effect, it has drawbacks such as side effects such as a decrease in water separation and properties, an increase in emulsification, and a decrease in electrical properties, which often causes problems in practical use. Particularly in the case of electrical insulating oil, the vapor emulsification value becomes extremely poor and it cannot be used. By adding an essentially amorphous ethylene-propylene copolymer to a specific electrical insulating oil base oil, the present invention achieves properties essential to electrical insulating oils such as electrical properties, oxidation stability, and demulsibility. The feature is that the pour point can be lowered without damaging the properties. In the present invention, in consideration of the economic efficiency of solvent dewaxing treatment and the effect of adding the ethylene-propylene copolymer, it is preferable that the pour point by ordinary solvent dewaxing treatment be -150C or lower. If the pour point of the base oil is too high, it is necessary to add a large amount of amorphous ethylene-propylene copolymer, which increases the viscosity of the product and reduces the cooling effect, which is an important property for electrical insulating oils. Undesirable. The amount of the essentially amorphous ethylene-propylene copolymer of the present invention added is 0.001 to 1. It can be added at a ratio of skin t%, preferably 0.01 to 0. desk t%
added.

The essentially amorphous ethylene-propylene copolymer used in the present invention is oil-soluble and usually has a weight average molecular weight of 10,000 to 10,000.
20,000 ~ 70,000 Usually the propylene content is 10~7%, preferably 20~70%
It's about 60% of the time. Essentially amorphous as used herein means that the copolymer may have some degree of crystallinity,
The degree of crystallinity is usually 0 to 5%, preferably 0 to 2%. Furthermore, the molecular weight distribution is preferably relatively narrow, usually 8
In particular, those of 4 or less are suitable for the purpose of the present invention.
These ethylene-propylene copolymers can be obtained by known specific methods.

Polymerization is carried out by mixing a specific homogeneous Ziegler-Natta type catalyst that is soluble in organic solvents in an inert organic solvent, at normal pressure to slightly increased pressure (usually about 1 to 20 k9'), at low temperature to slightly high temperature (
This is usually carried out by introducing ethylene, propylene and hydrogen gas into the catalyst mixture under conditions of about 150 to 50 qo. Ethylene and propylene have different polymerization reaction rates, and the polymerization reaction rate of ethylene is much higher than that of propylene. Therefore, the monomer ratio of ethylene and propylene does not match the content of ethylene and propylene in the produced copolymer. Therefore, in order to obtain an ethylene-propylene copolymer with a desired propylene content, it is necessary to pay close attention to the monomer ratio of ethylene and propylene. General formula V○(OR)nX as a homogeneous Thiekler-Natsuta type catalyst for obtaining the specific ethylene-propylene copolymer used in the present invention
3-n (where x is chlorine, bromine, or iodine, R is a hydrocarbon residue having 1 to 6 carbon atoms, and n is an integer of 0 to 3) and a vanadium compound with the general formula 2A , RASOX2 and R3ASO2X3 (wherein R is a hydrocarbon residue having 1 to 20 carbon atoms, which may be the same or different, respectively).

X represents chlorine, bromine or iodine). Specific examples of organoaluminium halides include diethyl aluminum chloride, diisopropylaluminium chloride, and thylaluminium dichloride. The inert organic solvent used during polymerization is a normal aliphatic or aromatic hydrocarbon. Preferred examples include n-hexane, heptane, toluene, and silene. Examples will be described below, but these are intended to clarify the present invention, and the present invention is not limited thereto.

Example 1 After atmospheric distillation of Middle Eastern (mixed base) crude oil,
The residual oil was distilled under reduced pressure to obtain crab oil (boiling point 240-41000 in terms of normal pressure, sulfur content 2.t%).

Next, add this crab extract oil to a solvent ratio (furfural/distillate oil) of 1.
3. Furfural is extracted at an extraction temperature of 75 to 9500, and this ruffinate is further processed into Nio-
Moo3 catalyst (Ni0:3. skin t%, Moo3:14.
0wt%), 32500, hydrogen pressure 40k9/Cruce○
, LHSVI. After hydrorefining treatment at 0, benzene-
Dewaxing was performed using toluene-methyl ethyl ketone as a solvent at a solvent ratio (solvent/oil) of 1.0 at a cooling temperature of -25 qo, and then a clay treatment was performed at 70 q0 for 1 hour to obtain a pour point of -22
．． 500 and a sulfur content of 0.09%, a first component refined oil (1) was obtained. Further, the same distillate oil used for refined oil (1) was extracted with furfural* at a solvent ratio of 1.0 and an extraction temperature of 75 to 990°C, and then this raffinate was mixed with refined oil (1).
) was subjected to solvent dewaxing and clay treatment under the same conditions as those used to obtain it, resulting in a pour point of -22.60 and a sulfur content of 0.
A refined oil (0) containing 9 t% of skin was obtained.

65 parts by weight of refined oil (1), 5 parts by weight of refined oil (0), and an olefin mainly composed of propylene tetramer are reacted with benzene using a boron trifluoride catalyst to synthesize alkylbenzene for branched detergents. An electric insulating oil base oil (2) was obtained by mixing 3 parts by weight of organic alkylbenzene having a boiling point of about 310 to 404° C. treated with Shirashi treatment at 70° C. for 1 hour (m).

This electrical insulating oil base oil W and this electrical insulating oil base oil have a weight average molecular weight of 40,000 and a propylene content of 37.5 mol%.
0.1 wt% of amorphous ethylene-propylene copolymer
Electrical insulating oil 'B} was obtained. Table 1 shows these properties.
It was shown to. As is clear from Table 1, the electrical insulating oil has a low pour point and is superior to base oil ① in other properties, making it an excellent electrical insulating oil. Comparative Example 1 0.00% polymethacrylate, a commercially available pour point depressant, was added to the electrical insulating base oil obtained in Example 1. t% was added to obtain electrical insulating oil (C).

Claims (1)

[Claims] 1 (I) Distillation of paraffin base crude oil or mixed base crude oil under atmospheric pressure, or distillation of residual oil from atmospheric distillation under reduced pressure, with a boiling point within the temperature range of 230-430°C (converted to normal pressure) Roughinate obtained by solvent refining distillate oil containing 80 wt% or more of Refined oil below 5%
A lubricating oil fraction of 90 wt% (II) mineral oil is mixed with at least 1 to 20 wt% of refined oil treated with a solid adsorbent (III) 5 to 90 wt% of arylalkane, and the total sulfur content is 0.
(IV) An essentially amorphous ethylene-propylene copolymer having a weight average molecular weight of 10,000 to 200,000 and a propylene content of 10 to 70 mol% is added to the electrical insulating oil base oil at a concentration of 35 wt% or less. 0.00 for oil
Oxidation stability and thermal stability obtained by adding 1 to 1.0 wt%,
An electrical insulating oil composition with excellent corona resistance, corrosion resistance, and low-temperature performance.