JPS60230304A - Electrically insulating composition - 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 Field of Industrial Application The present invention relates to electrically insulating compositions, particularly for capacitors, transformers,
The present invention relates to a composition useful as a high viscosity insulating oil for oil-filled electrical equipment such as reactors and cables.

BACKGROUND ART Conventionally, polybutene and polybutene mixed with various additives have been used as high-viscosity electrical insulating oils, but high-viscosity electrical insulating oils containing fluorine-containing cyclic acetal compounds have not been proposed.

In recent years, as the demand for electric power has increased, there has been a growing demand for higher voltage and larger capacity of electrical equipment such as transformers, capacitors, and power cables. As a result, even higher performance is required in terms of electrical properties, thermal stability, etc. required of electrical insulating oils used in electrical equipment.

OBJECTS OF THE INVENTION The present invention provides an electrically insulating composition that has a high dielectric constant and excellent voltage resistance and thermal stability.

Structure of the Invention The present invention relates to an electrical insulator containing a compound represented by the general formula: % formula %) [wherein Rf represents a perfluoroalkenyl group having 2 to 20 carbon atoms, and R represents hydrogen or an alkyl group] The present invention relates to sexual compositions.

The compound used in the present invention is a new compound, and is a cyclic acetal compound having a characteristic six-membered ring hindered structure. Based on this hindered structure, it has extremely high thermal stability and is liquid at a wide range of temperatures. .

The compound used in the present invention is a perfluoroalkenyl group having 2 to 20 carbon atoms, preferably a pentafluoropropenyl group derived from hexafluoropropene, an undecafluorohexenyl group, a pentadecafluorononenyl group, especially a hexafluoropropene group. It is preferable that the compound has a pentadecafluorononenyl group derived from a mer.

In order to provide the compound represented by the general formula [I] with preferable electrical properties, R must be hydrogen or an alkyl group, especially one having 1 carbon atom.
-3 alkyl groups are preferred. In order to be liquid over a wide range of temperatures, cyclic acetals should have a large number of side chains and a hindered structure to provide heat resistance.

The compound represented by formula [I] may be used alone as a high viscosity insulating oil, or may be used in combination with polybutene, etc., which have been conventionally generally used as a high viscosity insulating oil.

The compound represented by formula [I] is 2,2,4-)dimethyl-
Easily obtained by dehydrating 1,3-bentanediol and 1)-perfluoroalkenyloxybenzaldehyde or 1)-perfluoroalkenyloxyphenylalkyl ketone in the presence of an esterification catalyst, preferably in an organic solvent. Can be done.

The starting material, 2,2.4-1-limethyl-ni-1,3-pentanol, has two hydroxyl groups in positions suitable for forming a cyclic acetal from a steric structure, and the compound of the present invention can be produced in high yield. Since the cyclic acetal produced from the characteristics of structure-1- provides a characteristic hindered structure to the six-membered ring, a stable compound can be obtained.

The p-perfluoroalkenyloxybenzaldehyde or 1)-perfluoroalkenyloxyphenylalkyl ketone used in the present invention is, for example, a combination of 1]-hydroxybenzaldehyde or 1]-hydroxyphenylalkyl ketone and a hexafluoro a7'a pen oligomer. It is easier to react than this. Details of this reaction are described in, for example, Japanese Patent Publication No. 57-56454.

The dehydration reaction with 2,2,4-)trimethyl-1,3-pentanol, 1)-perfluoroalkenyloxybenzaldehyde or 1]-perfluoroalkenyloxyphenylalkyl ketone is carried out using equivalent amounts of both and an appropriate azeotropic reaction. Is this done by using a dehydration solvent, such as an aromatic solvent such as benzene, to react with a normal esterification catalyst, such as r+-)luenesulfonic acid, under heating conditions, and taking the produced water out of the system? preferable. When using an aromatic solvent, the reaction is preferably carried out under reflux conditions, for example, in the case of benzene, it is preferably carried out at 80'C or higher, and the reaction time is 1.
The target compound can be obtained with a yield of about 90% or more in about 2 hours.

Can this dehydration reaction be carried out without a solvent?Azeotropic dehydration using an aromatic solvent requires mild reaction conditions and is easy to control, and the yield is extremely high, making it extremely productive industrially. ing.

Effect of the invention .

The compound represented by formula [I] has higher electrical conductivity and higher visible gas generation voltage than polybutene, which is conventionally commonly used as a high viscosity insulating oil, so it is possible to increase the voltage of oil-filled electrical equipment, and it is especially When used as an impregnating agent for capacitors, it can be made smaller.

Reference Example 1 Synthesis of [2-methyl-2-(4'-perfluorononenyloxyphenyl)-4-isopropyl-5,5-tumethyl-], 3) oxane (compound l-1)] Stirring oven, temperature 1]-Hydroxyacetophenone 1 in a 500J7 flask equipped with a reflux condenser and a dropping port.
3.6 g (0.1 mol), N,N-dimethylformamide 80 J and triethylamine 1. og (0.1 mol) was charged. While maintaining the temperature of the reaction system below 211'C, 50% of hexafluoropropene trimer was added under stirring.
g (0.1] mol) was added dropwise into 7 rasfs. After the completion of the dropwise addition, the reaction was continued for about 2 hours, and the reaction mixture was poured into water. , and distilled under reduced pressure to obtain 45 g of Compound A (yield: 80%).

The physical properties of the obtained product were as follows.

Appearance: White Solid Boiling Point: 146-148℃/13 mmHB Melting Point: 4
2-44°C Synthesis of the compound of the present invention (compound ■-1): 14.6 g (0,
55 g (0,1 mol) of compound A and n-)luenesulfonic acid O, Ig and benzene l (1 (,1 mol)
(7) was charged into a Dean Stark distiller equipped with a stirrer and stirred at 100°C for 2 hours while removing the produced water from the thread by azeotropy. After the reaction was completed,
After neutralization and drying with anhydrous potassium carbonate, the solvent was distilled off, and then the product was obtained by vacuum distillation. It was confirmed that the product showed a single peak in gas chromatography under the following conditions: The physical characteristics of the obtained product are shown in Table 1.

Reference example 2 2-(4'-perfluorononenyloxyphenyl)-
Synthesis of 4-isopropyl-5,5-methyl-1-3-dioxane (compound 1-2); p-hydroxybenzaldehyde instead of p-hydroxyacetophenone 12. Reference example 1 except that 2g (+1.1 mol) was used.
Compound B was obtained similarly to the synthesis of compound A. Compound B
The physical properties of were as follows.

Appearance: Colorless liquid Boiling point: 142-145°C/23mmHg Refractive index:
1,6628 (n 23'C) Compound of the present invention (compound l
-2) Synthesis: Compound A was mixed with 3.6 g of the above compound BS (0
, 1 mol) in the same manner as in Reference Example 1 to obtain a product.

Gas chromatography (same conditions as Reference Example 1) of the obtained product showed a single peak. The physical properties of the product are shown in Table 1. The table also includes the physical properties of polybutene, which is conventionally used as a high-viscosity insulating oil.

EXAMPLES AND COMPARATIVE EXAMPLES The electrical properties of the compounds obtained in the above reference examples and of polybutene, which is a typical compound conventionally widely used as a high viscosity insulating oil, were measured as comparative examples and are shown in Table 2.

Claims (1)

[Claims] J, general formula: % formula %) Contains a compound represented by the formula 1, where "former" represents a perfluoroalkenyl group having 2 to 20 carbon atoms, and R represents hydrogen or an alkyl group. Electrical insulating composition.