JPH0612642B2 - Electrical insulating oil - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electric insulating oil, particularly an electric insulating oil suitable as a condenser oil.

Conventional technology As a condenser oil, natural oils and fats such as soybean oil, rapeseed oil and castor oil were used in old days. Since then, polychlorinated biphenyls (PCBs) have been used for many years because of their excellent electrical properties, but due to their strong toxicity to humans and persistent decomposition, their use has been banned in many countries including Japan. It was Therefore, many studies have been conducted to find a condenser oil to replace PCB, and now synthetic oils such as phenylxylylethane, diisopropylnaphthalene and silicone oil are the mainstream of condenser oil.

Problems to be Solved by the Invention Among the conventional condenser oils as described above, natural oils and fats such as soybean oil, rapeseed oil and castor oil all have a high pour point of about 0 to -20 ° C. There was a problem.
Furthermore, of these, soybean oil and rapeseed oil have a dielectric constant of approximately 3.1 (5
However, castor oil has a high dielectric constant of 4.5 (50HZ, 25 ° C), so it is partly used in DC capacitors for charging and discharging, but the dielectric loss tangent There was a problem that electrical properties such as volume resistivity and volume resistivity were not sufficient and the viscosity was high.

In addition, phenylxylylethane and diisopropylnaphthalene, which have recently become widely used, are subject to application restrictions due to the inherent problem of low flash point (about 150 ° C), and for vehicles such as JNR Uses expensive silicone oil.

In view of such a background, the present inventors have used castor oil having the characteristics of high flash point and high dielectric constant as a main raw material,
While minimizing the deterioration of these properties, the high pour point, which is a drawback of castor oil, is lowered, and the electrical characteristics such as dielectric loss tangent and volume resistivity, which are also the drawbacks of castor oil, are improved. As a result of repeated research, the present invention as described below has been reached.

Means for Solving the Problems The electrical insulating oil of the present invention is partially or completely acylated with a transesterification reaction product of castor oil or castor oil (20% by weight or more) and a natural fat / oil (80% by weight or less) having no hydroxyl group. And an acylated product having a hydroxyl value of 130 mgKOH / g or less.

Castor oil or a transesterification product of this with a natural fat or oil having no hydroxyl group has inferior electric characteristics such as dielectric loss tangent and volume resistivity, but it does not reduce hydroxyl groups that are negative due to acylation of the same. The extinguished acylated product has improved characteristics such as dielectric loss tangent and volume resistivity while maintaining the features of high flash point and high dielectric constant, and also has a low pour point and a marked decrease in viscosity. It exhibits the desirable property of facilitating impregnation of the substrate. When hydrogenated castor oil is used as a raw material instead of castor oil, the acylated product obtained by acylating the castor oil has a very high pour point, and its use as an electrically insulating oil is extremely limited.

Hereinafter, the present invention will be described in more detail.

(Acylation Raw Material) Castor Oil As the acylation raw material in the present invention, castor oil is first mentioned. Castor oil is a triglyceride whose main component is ricinoleic acid (12-hydroxyoleic acid),
About 90% of the constituent fatty acids are ricinoleic acid, and most of the remaining fatty acids do not have a hydroxyl group, so castor oil has a hydroxyl group of about 2.7 in the molecule.

Transesterification reaction product of castor oil and natural fats and oils having no hydroxyl group As the acylating raw material in the present invention, in addition to the castor oil, transesterification reaction product of castor oil and natural fats and oils having no hydroxyl group is also used, Use of this transesterification product as a raw material rather than castor oil alone provides more favorable results in terms of characteristics and cost.

Natural oils and fats that do not have a hydroxyl group include linseed oil, tung oil, rapeseed oil, soybean oil, coconut oil, palm oil, edible oil, walnut oil, rice bran oil, cottonseed oil, camellia oil, olive oil, cabbage oil and other vegetable oils. Animal oils such as beef tallow, lard, fish oil, liver oil and whale oil can be exemplified.

The transesterification reaction of castor oil and natural fats and oils having no hydroxyl group, the transesterification reaction usually performed, for example,
In the presence of an alkali catalyst such as alkali hydroxide, alkali metal alcoholate, sodium carbonate, etc., or a catalyst such as litharge, 1
A method of transesterification under reaction conditions of 80 to 260 ° C and 15 minutes to 6 hours is adopted.

The reaction ratio of castor oil and natural fats and oils that do not have a hydroxyl group is
When the total amount of the former and the latter is 100% by weight, the former is 20% by weight or more and the latter is 80% by weight or less, preferably the former is 95 to 20% by weight and the latter is 5 to 80% by weight, and particularly the former is 90% by weight. It is selected from the range such that the latter is 10 to 70% by weight, and the latter is 10 to 70% by weight. When the former is less than 20% by weight and the latter is more than 80% by weight, the hydroxyl groups are insufficient, the degree of acylation is insufficient, the pour point is not lowered, and the dielectric constant is lowered. When the latter ratio is less than 5% by weight, the effect is not so different from that of castor oil.

In the above transesterification reaction, other low molecular weight polyol may be used in combination within the range not departing from the spirit of the present invention.

(Acylation product) By acylating the acylation raw material as described above,
The desired acylated product is obtained.

Acylation is done by conventional acylation means. Of the acylations, acetylation is the most important. As the acetylation method, a method of reacting ketene, a method of reacting glacial acetic acid, or the like can be adopted, but acetylation with acetic anhydride is industrially most advantageous. Propionylation is
Usually, it is carried out using propionic anhydride.

As for the degree of acylation, when the acylation ratio is small, the electrical properties such as dielectric loss tangent and volume resistivity are inferior. The following is desirable.

(Combination with other electric insulating oil) As described above, the electric insulating oil of the present invention partially or completely acylated the transesterification reaction product of castor oil or a natural fat or oil having no hydroxyl group. Other known electrically insulating oils, such as alkylbenzenes (such as dodecylbenzene), alkylindanes, polybutenes, poly-α-olefins, phthalates (such as dioctylphthalate), diarylalkanes (such as phenylxylylethane). ), Alkylnaphthalene (such as diisopropylnaphthalene), alkylbiphenyl (such as monoisopropylbiphenyl), and a compound having an alkylene group and two or more aryl groups (1,1-diphenylethylene, 1,3-diphenylbutene-1,1,
4-diphenyl-4-methylpentene-1), triarylalkanes, terphenyls, arylnaphthalenes, aralkylnaphthalenes, silicone oils, mineral oils, vegetable oils, etc. because they have excellent compatibility with them. You can also In this case, the mixing ratio of the acylated product of the present invention and other known electric insulating oils can be widely varied, but the weight ratio is 5:95 to 95: 5, and particularly 10:90 to 9.
It is often selected from the range of 0:10.

An antioxidant and other additives can be added to the electric insulating oil of the present invention when it is used.

(Industrial Applicability) The electric insulating oil of the present invention is particularly suitable as a condenser oil, but if the electric insulating property is required, it can be used for any purpose including cable oil and transformer oil. it can.

EXAMPLES Next, the electrical insulating oil of the present invention will be further described with reference to examples. Hereinafter, “part” means “part by weight”.

(Synthesis of acylated product and general characteristic and electrical property of the obtained acylated product as a condenser oil) Example Castor oil (hydroxyl value: 162, acid value: 0.2, pour point: -22.5
200 ° C and rapeseed oil (acid value: 0.1, pour point: -17.5 ° C) 1
00 parts with a 28% methanol solution of sodium methylate
After reacting with 0.6 parts for 4 hours at 230-240 ° C, cooled, neutralized with 0.2 parts phosphoric acid (first-grade reagent), then added 3 parts activated clay and treated at 120 ° C for 1 hour. Acid value 1.
3, an oily substance having a hydroxyl value of 107.8 was obtained.

After reacting 280 parts of this oily substance with 54 parts of acetic anhydride at 140 ° C. for 2 hours, excess acetic anhydride and acetic acid by-produced were recovered under reduced pressure and treated with clay.

The acylated product thus obtained had an acetic acid value of 0.7 and a hydroxyl value of 2.7.

Next, the general properties and electrical properties of this acylated product as a condenser oil were investigated. The results are shown in Table 1.

Example 2 400 parts of castor oil and 100 parts of soybean oil were subjected to a transesterification reaction under the same conditions as in Example 1, and then 118 parts of acetic anhydride was added to the obtained product to carry out an acylation reaction in the same manner.

The acid value of the obtained acylated product was 0.6 and the hydroxyl value was 0.0.

Next, the general properties and electrical properties of this acylated product as a condenser oil were investigated. The results are also shown in Table 1.

Example 3 300 parts of castor oil and 100 parts of linseed oil were reacted in the same manner as in Example 1, and 88 parts of acetic anhydride was similarly reacted with the obtained product.

The acid value of the obtained acylated product was 0.8 and the hydroxyl value was 1.1.

Next, the general properties and electrical properties of this acylated product as a condenser oil were investigated. The results are also shown in Table 1.

Example 4 200 parts of castor oil and 200 parts of rapeseed oil were reacted in the same manner as in Example 1, and then 59 parts of acetic anhydride was similarly reacted with the obtained product.

The acid value of the obtained acylated product was 0.8 and the hydroxyl value was 0.0.

Next, the general properties and electrical properties of this acylated product as a condenser oil were investigated. The results are also shown in Table 1.

Example 5 200 parts of castor oil and 100 parts of rapeseed oil were reacted in the same manner as in Example 1, and then the obtained product was mixed with propionic anhydride 75
Parts were reacted similarly.

The acylated product thus obtained had an acetic acid value of 1.6 and a hydroxyl value of 0.0.

Next, the general properties and electrical properties of this acylated product as a condenser oil were investigated. The results are also shown in Table 1.

Example 6 500 parts of castor oil and 149 parts of acetic anhydride were reacted at 140 ° C. for 2 hours, and then excess acetic anhydride and by-produced acetic acid were recovered under reduced pressure.
It was treated with clay.

The acid value of the obtained acylated product was 0.3 and the hydroxyl value was 0.0.

Next, the general properties and electrical properties of this acylated product as a condenser oil were investigated. The results are also shown in Table 1.

Example 7 500 parts of castor oil and 73 of acetic anhydride were reacted at 140 ° C. for 2 hours, and then excess acetic anhydride and by-produced acetic acid were recovered under reduced pressure and treated with clay.

The acid value of the obtained acylated product was 0.7, and the hydroxyl value was 68.0.

Next, the general properties and electrical properties of this acylated product as a condenser oil were investigated. The results are also shown in Table 1.

Comparative Example 1 Castor oil (acid value: 0.3, hydroxyl value: 161.6) was examined for general characteristics and electrical characteristics as a condenser oil. The results are also shown in Table 1.

Comparative Example 2 Rapeseed oil (acid value: 0.1) was examined for general characteristics and electrical characteristics as a condenser oil. The results are also shown in Table 1.

(See Table 1) The results in Table 1 also show that the acylated product of the present invention has a low pour point, is difficult to catch fire, has a low viscosity, and has well-balanced electrical characteristics.

(Compatibility Test) The compatibility of each of the acylated products of Examples 1 to 7, the castor oil of Comparative Example 1 and the rapeseed oil of Comparative Example 2 with other known condenser oils was examined.

Compatibility with Phenylxylylethane The acylated products of Examples 1 to 7 and phenylxylylethane were mixed in a weight ratio of 3/1, 1/1, 1/3, and-
The sample was allowed to stand for one month at a temperature of 24 ° C, but neither phase separation nor turbidity occurred.

On the other hand, under the same conditions, a 3: 1 weight ratio mixture of castor oil and phenylxylylethane caused phase separation, and a 1/1 weight ratio mixture produced turbidity.

Further, under the same conditions, a mixture of rapeseed oil and phenylxylylethane in a weight ratio of 3/1 caused phase separation, and a mixture in a weight ratio of 1/1 caused turbidity.

Compatibility with diisopropylnaphthalene The acylated products of Examples 1, 2, 4, 6 and diisopropylnaphthalene were mixed in a weight ratio of 3/1, 1/1, 1/3, and the temperature condition was -24 ° C. It was left underneath for 1 week, but neither phase separation nor turbidity occurred.

On the other hand, under the same conditions, a mixture of castor oil and diisopropylnaphthalene at a weight ratio of 3/1 caused turbidity, and a mixture of rapeseed oil and diisopropylnaphthalene at a weight ratio of 3/1 caused phase separation. .

Compatibility with polybutene The acylated product and polybutene in Example 8 to be described later were mixed at a weight ratio of 3/1, 1/1, 1/3 and left at room temperature, but neither phase separation nor turbidity occurred. Did not occur.

On the other hand, under the same conditions, the mixture of castor oil and polybutene at a weight ratio of 3/1, 1/1, and 1/3 all caused phase separation. It should be noted that the mixture of rapeseed oil and polybutene at a weight ratio of 3/1, 1/1, 1/3 did not cause phase separation or turbidity under the same conditions.

These results also show that the acylated product of the present invention has excellent compatibility with other known condenser oils.

(Combination with other electrical insulating oil) Example 8 100 parts of castor oil and 200 parts of rapeseed oil were reacted in the same manner as in Example 1, and then 30 parts of acetic anhydride was similarly reacted with the obtained product. .

The acid value of the obtained acylated product was 0.6, and the hydroxyl value was 0.2.

The general characteristics and electrical characteristics of a mixture of the acylated product and phenylxylylethane in a weight ratio of 1: 2 were investigated as a condenser oil. The results are shown in Table 2.

As shown in Table 2, the acylated product of the present invention has excellent properties even when used in combination with other known condenser oils.

The electrical insulating oil of the present invention has a high flash point and is difficult to ignite, has a low pour point and can be used even under low temperature conditions, has a low viscosity, is easily impregnated into a base material, and has a high dielectric constant, Excellent electrical properties such as dielectric loss tangent, volume resistivity, dielectric breakdown voltage, and good compatibility with other well-known electrical insulating oils can be used in combination. .

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takashi Hamaguchi 1-26-85 Sakuradai, Yokkaichi-shi, Mie Prefecture

Claims (1)

[Claims] 1. An acylated product having a hydroxyl value of 130 mgKOH / g or less obtained by partially or completely acylating a transesterification reaction product of castor oil or castor oil of 20% by weight or more and natural oil / fat of 80% by weight or less having no hydroxyl group. Electrical insulating oil consisting of.