JPS604521B2 - Electrical insulation oil composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is based on a specific electric insulating oil base oil obtained by mixing a specified refined lubricating oil with a key oil obtained by refining a paraffin-base crude oil or a mixed base crude oil in a specified manner, and an ethylene-propylene copolymer. This invention relates to an electrical insulating oil composition with excellent thermal stability and low-temperature performance.

More specifically, (1) the boiling point (
The raffinate obtained by solvent refining crab extract oil containing 8 skin t% or more of crab content in the temperature range of 230 to 430 ° C (converted to normal pressure) is further hydrorefined and subjected to solvent dewaxing treatment,
If necessary, the sulfur content can be reduced to 0.25 wt% or less and the aromatic content to 18 to 3 by continuing solid adsorbent treatment.
80 to 9 parts by weight of refined oil made into skin t% is mixed with 1 to 20 parts by weight of refined oil, which is obtained by treating the lubricating oil component of (0) key oil with a solid adsorbent and is lower in aromatic content than (1). , the total sulfur content is 0.
Electrical insulating base oil with a weight average molecular weight of 10,000 to 200,000 (m) to 35M% or less.

0.001 to 1.0 w of an essentially amorphous ethylene-propylene copolymer with a pyrene content of 10 to 70 mol%
The present invention relates to an electrical insulating oil composition with excellent thermal stability and low-temperature performance, which is obtained by adding t%. 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, tin oil-based insulating oils use petroleum fractions as their main raw material and can therefore be supplied in large quantities at relatively low prices. Synthetic insulating oils are limited to some special uses. However, conventionally, this mineral oil-based insulating oil is not 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 the most important factor in producing tin oil-based insulation products. 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. There are many known methods for producing mineral oil-based electrical insulating oils, but conventional electrical insulating oils actually use naphthenic crude oil as the raw material, and electrical insulating oils are made from paraffin-based crude oil or mixed base crude oil. When producing oil, even if conventional methods for producing electrical insulating oil from naphthenic crude oil are applied, electrical insulating oil with satisfactory properties cannot be obtained.

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 65 to 96% hydrodesulfurized mineral oil, or to mix this with mineral oil having a lower aromatic content. However, in this case, it is stated that if the key oil is treated with a solvent before hydrodesulfurization, the oxidation stability etc. will be extremely poor (Japanese Patent Publication No. 36-18584). 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 key oil treated with sulfuric acid to this (Mochiseki 1974-46199).
.

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 (
Tokuko Shou 41-3 Maku 9).

As described above, each 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 paraffinic oils, the oxidation stability, hydrogen gas absorption, corona resistance, pour point, etc. are satisfied even if the production method from naphthenic base crude oils is applied as is. If you can't get what you want, you need to use a special and limited method. On the other hand, in recent years, as a method for producing insulating oil from paraffinic crude oil, a method has been disclosed in which an insulating oil with a low pour point is obtained by rectification after dewaxing treatment (Japanese Patent Publication No. 49-46123). however,
In this method, a refined oil having an aromatic content of about 14% at most is used, and the product insulating oil is obtained by adding an antioxidant. The present inventors have focused on the refining conditions for paraffin-base crude oil or mixed-base crude oil, not only to have good electrical properties among the various properties required for electrical insulating oil, but also to pay particular attention to the main property of thermal stability. As a result of intensive research, he discovered a method for stably producing an excellent electrical insulating oil and filed a patent application.
-74406).

In other words, in recent years, not only capacitors and cables but also transformers and disconnectors have been sufficiently degassed when filling with oil, and sealing methods such as diaphragm and nitrogen filling have been adopted after filling. At the bottom, there is less oxygen, and thermal stability is more important than oxidative stability (for example, Journal of the Japan Petroleum Institute, Vol. 17, No. 7, p. 16, 2).
4, 1974).

As a result of intensive research into the refining conditions for paraffin-based crude oil or mixed petroleum oil, the inventors of the present invention found that the oxidation stability, corona resistance, and corrosion resistance required for electrical insulating oil were maintained at a certain level of quality. In addition, we have discovered a method for producing electrical insulating oil that has excellent thermal stability as evaluated by heating it in an atmosphere with relatively little oxygen and testing the electrical properties of the oil after heating.

The present invention is characterized by adding a small amount of 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 the above-mentioned specific method, thereby causing no loss in other properties. The present invention relates to an electrical insulating oil composition that has significantly improved low-temperature properties without causing any damage.

The paraffin-based crude oil referred to in the present invention is a crude oil containing a large amount of paraffinic hydrocarbons, L. Petroleum Handbook, 1972.
As stated on page 19 of the sheep version (published by Sekiyu Shunjusha), the API gravity of the first key fraction of crude oil (kerosene fraction) is 40.
As mentioned above, the API specific gravity of the second key fraction (275-300 qC/40 willow Hg lubricating oil crab fraction) is 300 or more, and representative examples thereof include Pennsylvania crude oil, Minas crude oil, etc.

Mixed base crude oil is intermediate between paraffin base crude oil and naphthene base crude oil, and the API gravity of the first key crab is 33 to 400, and the API gravity of the second key crab is 20 to 300.
It is often found in Middle Eastern crude oil 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 present invention will be explained in more detail below.

The electrical insulating base oil used in the present invention is a mixed oil of refined oil (1) as the first component and refined oil (0) as the second component.

First, refined oil (1) is obtained as follows. Boiling point (normal pressure equivalent) obtained by atmospheric distillation of paraffin base crude oil or mixed base crude oil or vacuum distillation of shallow pickling oil distilled under atmospheric pressure 23
Crab content within the temperature range of 0 to 430 qo, preferably 250 to 400 qo, is 8 t% or more, preferably 9 t%.
% or more of crab oil 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 100 degrees, preferably 60 to 9,000 degrees, and the ratio (volume ratio) of furfural to key oil is 0.3 to 2. The castle order is preferably 0.5 to 1.
The range is 5. Next, the raffinate obtained by solvent refining is hydrorefined and subjected to solvent dewaxing treatment in order to obtain a predetermined pour point. Furthermore, if necessary, clay 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 selected so that the sulfur content of refined oil (1) is 0.25 M% or less and the aromatic content is 18 Wt% to 3%. .

When the aromatic content is 18-3% by weight, the viscosity (@30qo) of the refined oil (1) is 4-1 SL, preferably 5-1 SL.

In the present invention, the aromatic group of this refined oil (1) is 22 to
Most preferably it is 25M%. The aromatic content in the present invention is the content (%) measured by percolating key oil on silica gel.

That is, there is no need to limit the purification scope of each of solvent purification and hydrotreating, and it is possible to select purification conditions with great flexibility by combining both to ensure the above-mentioned properties. The catalyst used in the hydrorefining in the present invention is the oxidation of metals from group 1, group IB, and blood group of the periodic table using bauxite, activated carbon, Fuller's oxide, keiso, zeolite, alumina, silica, silica-alumina, etc. as a carrier. It is usually used after pre-sulfurization.

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 aluminum oxide-containing carrier is particularly preferably used. The reaction temperature in the hydrorefining treatment of the present invention is usually about 230 to about 345 oo, preferably 260 to 32 oo. At low temperatures, the reaction rate is low, and at high temperatures, the paraffin content increases due to decomposition, causing the pour point to rise slightly and the color of the product to be unfavorable. The reaction pressure is at least 25 kg'G, preferably 25 to 75 K9/G, most preferably 35 to 45 X9 G/G. Further, the hydrogen is 100 to 10,000N, preferably 20N to the feedstock oil 1.
Make contact in the range of 0 to 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 a solvent so that the viscosity of the solution supplied 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 referred to herein refers to a treatment in which a solid adsorbent such as acid white clay, activated clay, fullerite, alumina, silica alumina, etc. is brought into contact with tin oil. Contact is usually made at about 50-80 pm for about 30 minutes to several hours. The contact method may be a percolation method or a contact method. In the present invention, on the other hand, a refined oil (b) whose aromatic content is lower than that of the refined oil (1) by treating the lubricating oil fraction of mineral oil with a solid adsorbent is added to the refined oil so that the total sulfur content of the mixed oil is 0. An electrical insulating oil base oil is obtained by mixing refined oil (0) in an amount not exceeding 35 M% and in a range of 1 to 2 parts by weight.

The refined oil (0) in the present invention is obtained as follows.

The key oil used as the second component, refined oil (0), is usually obtained by distilling various crude oils and has a boiling point of about 230 to 4,600.
The lubricating oil fraction containing approximately 8% or more in the temperature range of 0 (converted to normal pressure) is treated with a solid adsorbent, and before the solid adsorbent treatment, it is subjected to solvent purification, dewaxing, and sulfuric acid purification. These can be performed alone or in combination. In the present invention, it is particularly preferable to perform solvent purification treatment before solid adsorbent treatment. The solvent refining treatment mentioned here is the same refining treatment as that used to obtain the refined oil (1) described above. In addition, the sulfuric acid refining treatment is carried out under the same conditions as those for the sulfuric acid treatment of mineral oil.
M%. In the present invention, 1 part of the mineral oil as the second component obtained in this manner is added to 80 to 9 parts by weight of the first component.
~2 parts by weight, preferably 3 to 1 parts by weight, and the total sulfur content is 0.35 wt% or less, preferably about 0.05 to 0.3
Let it be Wt%.

In this application, as mentioned above, when solid adsorbent treatment is also performed when obtaining the first component, the hydrorefined dewaxed oil for the first component and the lubricating oil crab fraction for the second component are mixed and then simultaneously. Solid adsorbent treatment can be carried out.

Further, after adding a predetermined amount of an essentially amorphous ethylene-propylene copolymer described later to the mixed oil of the dewaxing oil for the first component and the lubricating oil for the second component, a mass adsorbent is simultaneously added. Processing can also be performed. 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. This invention relates to a more improved 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
-27.5℃ which passes IS standard (JIS-2320)
This is almost the limit for ordinary dewaxing equipment, and from the viewpoint of economic efficiency, it is desirable that the pour point to be lowered by dewaxing treatment be at least about 125 qo or more.

The present invention improves the above-mentioned 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 processed by adding a small amount of essentially amorphous ethylene-propylene copolymer. -27
．． It is characterized in that it produces a final product with a very low pour point of 5° C. or lower, or -40° C. or lower, which cannot be reached by ordinary solvent dewaxing treatment.
Accordingly, most of the pour point depressants 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, 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 is -15q0 or less. If the pour point of the base oil is too high, it will be necessary to add a large amount of amorphous ethylene-propylene copolymer, which will increase the viscosity of the product and reduce its 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 relative to the electrical insulating base oil.

001~1. It can be added at a ratio of skin t%, preferably 0.01 to 0. is added at t%.

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 joshumasashi〈20,000 to 70,000, usually the propylene content is 10 to 7 hol%, preferably 20
~6 dishes ol%. 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-bropyretho copolymers can be obtained by known specific methods.

Polymerization is carried out by mixing a specific homogeneous Teigler-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 x 9'), 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 5 pC). 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. A homogeneous Ziegler system for obtaining the specific ethylene-propylene copolymer used in the present invention.

As a Natta type catalyst, the general formula V0(OR)nX3-n(
However, X is chlorine, bromine, or iodine, and R has 1 to 6 carbon atoms.
(n is an integer of 0 to 3) and the vanadium compound represented by the general formula R2AIX. Consisting of organoaluminum halides represented by RNX2 and R3AI2×3 (where R is a hydrocarbon residue having 1 to 20 carbon atoms, and each may be the same or different. × represents chlorine bromine or iodine) Coordination catalysts are preferred. Specific examples of organoaluminum halides include diethylaluminum chloride, diisopropylaluminum chloride, and ethylaluminum dichloride. During polymerization, the inert organic solvent used is usually an aliphatic or aromatic hydrocarbon. Specifically, n-hexane, heptane, toluene, xylene, etc. are preferably used. Examples will be described below, but these are intended to illustrate the present invention, and the present invention is not limited thereto.

Example 1 and Comparative Example 1 After atmospheric distillation of Middle Eastern (mixed base) crude oil, the residual bamboo oil was distilled under reduced pressure.
At 8:00 p.m., sulfur content of 2.1 wt% and aromatic content of 3 t%) were collected.

Next, add this crab extract oil to a solvent ratio (furfural/distillate oil) of 1.
4. Furfural is extracted at an extraction temperature of 70 to 90°C, and this raffinate is further extracted with Ni○-Mo using alumina as a carrier.
o3 catalyst (Ni○: 3.% of enemy, MOO3: 14. skin t
%), G, LH of 310qo, hydrogen pressure 40k9'
SVI. After hydrorefining treatment at 0.0 mL, dewaxing was performed using benzene-toluene-methyl ethyl ketone as a solvent at a solvent ratio (solvent/oil) of 1.6 and a cooling temperature of -30 pm, and then a solid adsorbent using alumina gel. After treatment, the pour point was 27.5 qo, the sulfur content was 0.0 t%, and the aromatic content was 24 wt.
% and a viscosity (@30° C.) of 7.26 St, a refined oil (1) was obtained. Oxidation stability test of refined oil (1) (JISC210
The acid value of 1) was 2.15, 2KOH'.

92 parts by weight of this refined oil (1) was mixed with crab extract oil distilled under reduced pressure, the same as that used for refined oil (1), at a solvent ratio of 1.6 and an extraction temperature of 70%.
Furfural was extracted at ~90:00, then this raffinate was subjected to solvent dewaxing treatment in the same machine as refined oil (1), and then white clay treatment was performed for 1 hour at 70:00.
) (sulfur content: 0.75M%, aromatic content: 2%) by mixing 8 parts by weight of electrical insulating oil base oil-like properties, and this base oil has a weight average molecular weight of 45,000 and a propylene content of 37 moles. % amorphous ethylene-propylene copolymer to 0.1M
Table 1 shows the properties of electrical insulating oil 'B}. For comparison, polymethacrylate, a commercially available pour point depressant, was added at 0.0% to the electrical insulating oil base oil. The properties of electrical insulating oil [q] to which fine t% was added are also listed in Table 1.

As is clear from Table 1, the electrical insulating oil containing polymethacrylate has a lower pour point than the base oil, but its electrical properties, demulsibility, and thermal stability are significantly worse, making it difficult to use as an electrical insulating oil. cannot be used.

On the other hand, electrical insulating oil containing ethylene-propylene copolymer is an excellent electrical insulating oil with a low pour point and other properties similar to those of the base oil. Table 1 * JIS C2101, ** JISK251 **
*ASTMD I934 Non-Catalyst Example 2 Same as Example 1 except that the cooling temperature of the solvent dewaxing treatment performed when obtaining refined oil (1) and refined oil (0) in Example 1 was set to -2000. Electrical insulating oil base oil {
gained merit.

An electrically insulating oil leg was obtained by adding 0.05 M% of an amorphous ethylene-propylene copolymer having a weight average molecular weight of 30,000 to 50 mol% of propylene content to this base oil [D]. Table 2 shows the properties of the electrical insulating oil base oil pan and the electrical insulating oil [E]. As is clear from Table 2, by adding an amorphous ethylene-propylene copolymer to the base oil obtained by economically dewaxing, it is possible to achieve low pour point, oxidation stability, electrical properties, and demulsibility. An excellent electrical insulating oil was obtained. Table 2 Example 3 The cooling temperature of the solvent dewaxing treatment performed when obtaining refined oil (1) and refined oil (D) in Example 1 was set to -25o.
Electrical insulating oil base oil (F) was obtained in the same manner as in Example 1 except that o was used.

To this base oil {F, 0.03% of an amorphous ethylene-propylene copolymer with a weight average molecular weight of 30,000 and a propylene content of 50 mol% was added to produce electrical insulating oil (■), and 0.1M% was added to produce electrical insulating oil ( H) was obtained. Table 3 shows their properties. 3

Claims (1)

[Claims] 1 (I) A distillate having a boiling point (converted to normal pressure) in the temperature range of 230 to 430°C obtained by atmospheric distillation of paraffin base crude oil or mixed base crude oil or vacuum distillation of the residual oil of atmospheric distillation. Roughinate obtained by solvent refining distillate oil containing 80 wt% or more is further hydrorefined, subjected to solvent dewaxing treatment, and if necessary, subsequently treated with a solid adsorbent to reduce the sulfur content to 0.25 wt% or less. , aromatic content 1
(II) to 80 to 99 parts by weight of refined oil adjusted to 8 to 30 wt%.
An electrical insulating oil base oil made by treating a lubricating oil fraction of mineral oil with a solid adsorbent, mixed with 1 to 20 parts by weight of a refined oil with lower aromaticity than (I), and having a total sulfur content of 0.35 wt% or less. to (I
II) 0.001 to 1.0 w of an essentially amorphous ethylene-propylene copolymer with a weight average molecular weight of 10,000 to 200,000 and a propylene content of 10 to 70 mol%.
An electrical insulating oil composition with excellent thermal stability and low-temperature performance.