JPS58164107A - Insulating oil - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flame-retardant insulating oil, and an object thereof is to obtain an insulating oil that is flame-retardant and has a low viscosity.

Due to the demand for flame retardancy and miniaturization of electrical equipment such as oil-immersed transformers and capacitors, the PCs that have traditionally been used
Silicone oil has come to be used instead of B.

As an insulating oil that is monovalent and more flame retardant than silicone oil, a mixture of aryl phosphate and mineral oil-based insulating oil is already known. However, mineral oil-based insulating oil
They have the disadvantage that they generally have low solubility with respect to aryl phosphates.

The present inventors have discovered that acetyl trialkyl citrate, al or trialkyl citrate, or a mixture thereof with trialkyl phosphate and/or dialkyl phosphonate contains at least one aromatic mt. The present invention was completed based on the discovery that the phosphoric acid triester is dissolved in any blending ratio to form a blended oil, and that these blended oils are flame retardant and have low viscosity.

The object of the present invention is to form a novel flame-retardant insulating oil by blending acetyl trialkyl citrate or trialkyl citrate with a phosphoric acid triester containing 1lt-at least 111i1 of aromatic group, or blending them. The object of the present invention is to provide a T1 flame-retardant insulating oil by further blending a phosphoric acid trialkyl ester and/or an alkylphosphonic acid dialkyl ester with the oil.

To summarize the present invention, the present invention provides acetyl trialkyl citrate or trialkyl citrate with aromatic a
The present invention relates to an insulating oil characterized in that 30 to 80 by weight of at least one phosphoric acid triester is blended based on the total composition.

Furthermore, the present invention further provides for an insulating oil containing acetyl trialkyl citrate or a combination of trialkyl citrate and phosphoric acid triester to the total composition of the insulating oil containing trialkyl phosphate and/or dialkyl phosphonate. 10 to 80% by weight, based on the invention.

A typical trialkyl acetyl citrate used in the present invention is represented by the following general formula: %C (where n represents a number from 2 to 8). Further, a typical trialkyl citrate is represented by the following general formula: % formula % (wherein n represents a number from 2 to 8).

The phosphoric acid triester containing at least one aromatic lII that is blended into these refers to one in which at least lIIm of the three ester components in the orthophosphoric acid triester contains an aromatic jj. , for example,
Tricresyl phosphate, phosphorus diphenyl phosphate, octyl diphenyl phosphate, tricylenyl phosphate, diphenyl orthoxylenyl phosphate, phosphoric acid)'j (ethylphenyl), phosphoric acid) + 7 (infusebir phenyl), phosphorus Acid phenyl di C isopropylphenyl), tri(n-propylphenyl) phosphate, tri(butylphenyl) phosphate, phosphorus al) IJ (pentylphenyl), phosphoric acid)! These esters include tri(heptylphenyl) phosphate, tri(octylphenyl) phosphate, phosphorus II)IJ(nonylphenyl) and tri(decylphenyl hyphosphate), and these esters can be used alone. However, a mixture of two or more of these may be blended.

Typical phosphoric acid trialkyl esters are:
It is represented by the following general formula: % formula % (in the formula C, n represents a number from 4 to 11). Examples of phosphate trialkyl esters represented by these general formulas include tributyl phosphate, tripentyl phosphate, trihexyl phosphate, triheptyl phosphate, trioctyl phosphate, trinonyl phosphate,
There are esters such as tridecyl phosphate and triundecyl phosphate.

Further, a typical alkylphosphonic acid dialkyl ester is represented by the following general formula: (% formula %) where m and n are the same or different and represent a number from 4 to 9.

Examples of purkylphosphonic acid dialkyl esters represented by these general formulas include diptyl butylphosphonate,
Esters include dipentyl pentylphosphonate, dihexyl hexylphosphonate, diheptyl heptylphosphonate, dioctyl octylphosphonate, dinonyl nonylphosphonate, and diptyl octylphosphonate.

The phosphoric acid trialkyl ester and the alkylphosphonic acid dialkyl ester described above can each be blended alone, or a mixture of two or more thereof may be blended. Furthermore, if the number of carbon atoms (m and n) in the alkyl group is less than 4, the compatibility with other esters will be poor, and on the other hand, the number will be greater than the upper limit. It will no longer be liquid.

At least 11 aromatic compounds blended with acetyl trialkyl citrate or trialkyl citrate
1! The amount of phosphoric triester contained is 30 to 80% by weight, more preferably 40 to 80% by weight, based on both compositions.
Weight - is appropriate. If the amount is less than this, the flame retardant effect cannot be expected much, and on the other hand, if it is more than the upper limit, the dielectric loss tangent becomes extremely high, which is not preferable.

Furthermore, regarding the amount of phosphoric acid trialkyl ester and/or alkylphosphonic acid dialkyl ester to be added to the above-mentioned blended oil, from the viewpoint of reducing the viscosity of the above-mentioned blended oil, an amount of 10% by weight or more based on the total amount is effective. is demonstrated. On the other hand, if the amount exceeds 80% by weight, the dielectric loss tangent of the oil will become very high, which is undesirable. Therefore, this amount is preferably 10 to 80% by weight.

Hereinafter, the effects of the present invention will be explained in detail using one example, but the present invention is not limited to these in any way.

The flammability of the blended oils in Examples and Comparative Examples was measured as follows.

A glass tape with a width of 25w1 and a length of 500cm and a thickness of 0.25mm was immersed in sample oil somg for 3 minutes, then taken out from the oil, left horizontally for 2 hours, and then placed on one end of the glass tape with the flame of a gas burner. ignite.

Flammability was evaluated based on the burning rate (seconds/cm2) after ignition.If the flame extinguished even after ignition, it was judged as having no flammability.

Example 1 Two types of trialkyl acetyl citrate and two types of triplekyl citrate were blended with tricylenyl phosphate in a range of 10 to 90% by weight based on both compositions, and the flammability of the resulting blended oil was evaluated. Measure your friend.

In addition, 10 to 90 weight ratios of acetyltri-2-ethylhexyl citrate, tributylcy)L/-)t- and 4 types of phosphoric triesters containing at least one aromatic *1 are added based on the respective compositions. Then, the flammability of the nine blended oils obtained was measured. The obtained valley results are shown in Table 1, Table 2, and Table 3.

As is clear from Tables 1, 2, and 3, a phosphoric acid triester containing at least one aromatic compound is added to trialkyl citrate or trialkyl citrate. Based on this, if it is blended in an amount of 30% or more by weight, it becomes self-extinguishing.

Note that when 30% by weight or more is blended, a combustion rate equivalent to that of silicone oil can be obtained, and the blended amount of phosphoric acid triester is preferably 30% by weight or more, but preferably 40% by weight.
The above is better. Example 2 Trixylenyl phosphate, acetyl tri-2-ethylhexyl citrate, or tributyl citrate and t60
Based on the total composition, 10 to 40 of trioctyl phosphate or diptyl butylphosphonate was blended into the oil at a ratio of 10 to 40, and the viscosity of the resulting blended oil was measured. The results are shown in Tables 4 and 5.

From Tables 4 and 5, phosphoric acid trialkyl esters or alkylphosphonic acid dialkyl esters were prepared in Example 1.
It can be seen that when more than 10% of the total composition is added to the blended oil, the viscosity of the blended oil decreases significantly. 9. It can be seen that even if these phosphoric acid trialkyl esters and/or alkylphosphonic acid dialkyl esters are blended, a flame-retardant insulating oil with low viscosity and flame retardance can be obtained. Example 3 Tricresyl phosphate was blended with acetyl-2-ethylhexyl citrate, and the dielectric loss tangent of the resulting nine-blended oil was measured. Mayu mixed trioctyl phosphate with a blended oil containing acetyl-2-ethylhexyl citrate and tricresyl phosphate in a ratio of 50:50, and measured the dielectric loss tangent of the resulting nine blended oils. The results obtained are shown in Tables 6 and 7.

Table 6 (Dielectric loss tangent of insulating oil) Unit: 1G (80t) Table 7 (Dielectric loss tangent of insulating oil) Unit: 1G (8 (1) From Tables 6 and 7, acetyl-2-ethyl Phosphate triester containing at least one aromatic compound to be blended with silcitrate has a large dielectric loss tangent when blended with 80% by weight or more, so from the viewpoint of flame retardancy, it may be blended up to 90% by weight. , 80 weight or less is found to be appropriate.

It has been found that the appropriate amount of phosphoric acid trialkyl ester and/or alkylphosphonic acid dialkyl ester to be added to these blended oils is 80% by weight or less in terms of dielectric loss tangent.

Claims (1)

[Claims] 1. 30 to 80 weight portions of phosphoric acid triester containing at least one aromatic ring are blended with trialkyl acetyl citrate, based on the total composition. 1-Characteristics Insulating oil. 2. Insulating oil containing 30 to 80% by weight of phosphoric triester containing at least one aromatic ring to trialkyl citrate, based on the total composition. 3. Insulating oil containing t% mold. For the insulated hydraulic pressure in which acetyl trialkyl citrate and trialkyl citrate and phosphate ester tube are mixed in ranges 1 and 2, phosphoric acid trialkyl ester and/or alkylphosphonic acid dialkyl ester are added to the entire composition. Based on 10 to 80 weight formulations, nine characteristics of insulating oil.