Electrical insulating oils
AssigneeNippon Oil Co., Ltd.
InventorsMidori Masunaga, Yoshiki Kohno, Hiroshi Hasegawa
Life of this patent
Estimating the term…
Abstract
An electrical insulating oil having excellent thermal stability and low-temperature properties, which consists essentially of (A) 80-99 parts by weight of refined oil having a low sulphur content and considerable aromatic content and being prepared from a distillate contained in a fraction boiling between 230.degree.-430.degree. C of a paraffin or mixed base crude oil origin, (B) 1-20 parts by weight of a refined oil prepared from a lubricating oil fraction of a mineral oil boiling between 230.degree.-460.degree. C of any crude oil origin and, if desired, (C) 0.001-1.0 part by weight of an essentially ethylene-propylene copolymer as the additive.
Claims13
An electrical insulating oil consisting essentially of (A) 80-99 parts by weight of a refined oil (I) containing not more than 0.25 wt.% of sulphur and 18-30 wt.% of aromatic compounds, the refined oil (I) being produced by the steps of:
- refining with a solvent capable of selectively dissolving aromatic compounds a distillate contained in a fraction having a boiling range of 230.degree.-430.degree. C at atmospheric pressure obtained by the distillation of a paraffin or mixed base crude oil at atmospheric pressure or the distillation at a reduced pressure of a bottom oil obtained by the distillation of the crude oil at atmospheric pressure thereby to obtain a raffinate from said distillate,
- hydrofining the raffinate so obtained and
- dewaxing the thus hydrofined raffinate with a solvent, and (B) 1- 20 parts by weight of a refined oil (II) having an aromatic content of 14 to 29% and lower than that of the refined oil (I), the refined oil (II) being prepared by treating at least with a solid adsorbent a lubricating oil fraction of a mineral oil having a boiling range of 230.degree.-460.degree. C at atmospheric pressure obtained from a crude oil, to obtain the electrical insulating oil having a total sulphur content of not more than 0.35 wt.% and excellent thermal stability.
An electrical insulating oil consisting essentially of (A) 80-99 parts by weight of a refined oil (I) containing not more than 0.25 wt.% of sulphur and 18-30 wt.% of aromatic compounds, the refined oil (I) being produced by the steps of:
- refining with a solvent capable of selectively dissolving aromatic compounds a distillate contained in a fraction having a boiling range of 230.degree.-430.degree. C at atmospheric pressure obtained by the distillation of a paraffin or mixed base crude oil at atmospheric pressure or the distillation at a reduced pressure of a bottom oil obtained by the distillation of the crude oil at atmospheric pressure thereby to obtain a raffinate from said distillate,
- hydrofining the raffinate so obtained and
- dewaxing the thus hydrofined raffinate with a solvent, and (B) 1-20 parts by weight of a refined oil (II) having an aromatic content of 14 to 29% and lower than that of the refined oil (I), the refined oil (II) being prepared by treating at least with a solid adsorbent a lubricating oil fraction of a mineral oil having a boiling range of 230.degree.-460.degree. C at atmospheric pressure obtained from a crude oil thereby to obtain a base oil for the electrical insulating oil, the base oil having a total sulphur content of not more than 0.35 wt.%, and (C) 0.001-1.0 part by weight per 100 parts by weight of said base oil, of an essentially amorphous ethylene-propylene copolymer (III) having a weight average molecular weight of 10,000- 200,000 and a propylene content of 10-70 mol%, whereby is obtained the electrical insulating oil having an excellently low pour point as well as excellent, thermal stability.
Dependencies are inferred from the claim text.