JPS6015088B2 - Tricresyl phosphate oil for electrical insulation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tricresyl phosphate oil for electrical insulation.

In recent years, tricresil fluoride, which has properties such as flame retardancy and high dielectric constant, has been used as an insulating oil for oil-filled electrical equipment such as capacitors, transformers, reactors, and cables, from the viewpoint of flammability or downsizing. Osphate (hereinafter simply T
CP) is used alone or in combination with other insulating oils.

However, due to circumstances in the industrial production of raw material cresol, currently commercially available TCP has a pour point of -30q at most.
It is approximately 0, and oil-filled electrical equipment using this TCP alone cannot be used under conditions of 13 pi or less.

Furthermore, even if a mixture of insulating oil with another insulating oil having a low pour point is used, the pour point will be determined by the mixing ratio of TCP. Therefore, T used for this type of equipment
There is a strong demand for a lower pour point of CP without impairing its excellent properties. The ingredients for one example of a commonly available TCP product were approximately as follows.

01 Tri-(p-resyl) phosphate content ratio-
5% by weight.

■ Mono(m-cresyl)-g(p-cresyl) phosphate (m, p, p isomer), content u combination approx. 3
1% by weight.

[31 D-(m-cresyl)-mono-(p-cresyl) phosphate (m, m, p, isomer), content ratio-
Approximately 51% by weight.

[41 Tory (m-resil) phosphatate (m,
m, m, isomer), content - about 1% by weight.

As a result of examining various combinations of each component of TCP, the inventors found that by setting the content of m, m, and p isomers as components to 75 to 9% by weight, excellent properties as TCP could be achieved. It has been discovered that the pour point can be reduced to -3 total 0 or less without any damage.

As understood from the examples below, the content of m, m, and p isomers is preferably 75 to 9% by weight, but is limited to this due to the relationship with other components. isn't it.

Note that the upper limit is set at 99% by weight here because it is difficult to purify industrially to a purity of 9% by weight or higher, and from the viewpoint of electrical properties, there is no problem at all even with a purity of 9% by weight. .

Examples of the present invention will be described in detail below.

Note that tricresyl phosphate oils for electrical insulation (hereinafter simply referred to as TCP oils) were prepared according to Examples 1 to W below.
) are shown in Table 1. The pour points in Table 1 were measured in accordance with JISC2101-1974 (electrical insulating oil testing method). Example 1 The commercially available TCP described above was gradually cooled, and the crystal precipitates obtained at -25°C were filtered out and removed.
The content ratios of m, m, and p isomers in CP were adjusted.

Example 0 Synthesis was carried out by stirring 1*mol of mono-(p-cresyl)phosphoryl chloride and 2 moles of m-cresol in benzene using anhydrous magnesium chloride as a catalyst to react.

The product was washed with water and distilled repeatedly to obtain purified m, m, p, and isomers. Example m Mixed cresol in a ratio of 1 mole of p-cresol, 2 moles of m-cresol, and phosphorus oxychloride are reacted in benzene with anhydrous magnesium chloride as a catalyst,
TCP was synthesized by purification as in Example 0.

Example W The main component is the m, m, p isomer of Example B, and m
- m, m obtained by reacting cresol and phosphorus oxychloride
, m isomers were mixed at a ratio of 3:1, and the content ratios of m, m, p, and isomers were adjusted.

As is clear from Table 1, the properties of the TCP oils according to Examples 1 to 1 W are approximately the same as those of conventional commercially available TCP oils, and the pour point is −35 qo or lower.

As described in detail above, according to the present invention, it is possible to obtain TCP oil with a low pour point without impairing the excellent properties of TCP, so it has the effect of being able to be used at lower temperatures than conventional commercially available TCP.

In addition, in the above-mentioned example, the case where TCP oil was used alone was described, but for example, other insulating oil and the above-mentioned TCP oil were used.
Of course, by mixing with oil, the pour point of the mixed oil may be lowered or the electrical characteristics may be improved.

Claims (1)

[Claims] 1. The content of di-(m-cresyl)-mono-(p-cresyl) phosphate, which is one component in tricresyl phosphate oil, is 75 to 99% by weight, and the pour point is -
A tricresyl phosphate oil for electrical insulation, which is characterized by a temperature of 35°C or lower.