Abstract: The present invention relates to an improved electrical insulating oil composition which has excellent electrical characteristics and is suitable for use in impregnating electrical appliances in which plastic dielectric material is used, and further relates to electrical appliances impregnated with such a composition. The electrical insulating oil composition is produced by bringing a by-product oil fraction mainly containing components having boiling points in the range of 260.degree. to 330.degree. C. (atmospheric pressure basis) into liquid-liquid contact with an organic polar solvent; said by-product oil fraction being formed by alkylating benene or toluene with ethylene in the presence of an alkylation catalyst and then distilling the alkylation product; and said electrical insulating oil composition being characterized in that the ratio of the integrated intensity as chemical shift at 120 to 155 ppm of the spectrum measured by .sup.

Abstract: A method for producing an electrical insulating oil composition composed of benzyltoluene and ditolymethane. The composition is excellent in low-temperature characteristics and contains substantially no chlorine. The method comprises the steps of reacting monocyclic aromatic hydrocarbon with diarylmethane which has been prepared without using a chlorinated hydrocarbon as a starting material, at a temperature of -10.degree. to 550.degree. C. in the presence of a disperoportionation catalyst to prepare a reaction product containing benzyltoluene and ditolylmethane, and recovering benzyltoluene and ditolylmethane from said reaction product by distillation.

Abstract: A method for producing m-benzyltoluene with a high yield and excellent selectivity without producing undesirable heavier by-products. The method is characterized in that toluene and diphenylmethane are allowed to react at a reaction temperature in the range of 170.degree. to 400.degree. C. in the presence of a crystalline synthetic zeolite catalyst in which the molar ratio of SiO.sub.2 /Al.sub.2 O.sub.3 is 20 or higher and the openings of main pores are formed by ten-membered oxygen rings.

Abstract: An improved oil-filled capacitor which is excellent in low temperature characteristics. The oil-filled capacitor is composed of at least partially a plastics material and is impregnated with an electrical insulating oil which oil is characterized in that it comprises 0 to 100% by weight of a fraction A containing components boiling within the range of 268.degree. to 275.degree. C. (atmospheric pressure basis) and 100 to 0% by weight of a fraction B containing components boiling within the range of 280.degree. to 310.degree. C. (atmospheric pressure basis) which fractions are recovered by distillation from the heavy by-product oil that is produced in the preparation of ethylbenzene by alkylating benzene with ethylene in the presence of an alkylation catalyst and the ratio of the integrated intensity as chemical shift at 120 to 155 ppm of the spectrum measured by C.sup.

Abstract: The present invention relates to a method for refining an electrical insulating oil by refining a heavy by-product oil obtained in the preparation of ethylbenzene or ethyltoluene. The method comprises distilling off the lighter components from the by-product oil, then dehydrogenating, distilling and hydrogenating.

Abstract: An electrical insulating oil composition which is excellent in low temperature characteristics and suitable for use in impregnating capacitors, and comprises (a) m-ethylbiphenyl, (b) p-ethylbiphenyl, (c) m-isopropylbiphenyl and (d) p-isopropylbiphenyl, and is characterized in that the total amount of the ethylbiphenyls is not less than 40% by weight and the proportion of solid phase in the composition at a temperature of -40.degree. C. is not more than 45% by weight, the solid quantity of each component being calculated according to the following equation of solid-liquid equilibrium: ##EQU1## wherein X.sub.1 is the equilibrium mole fraction of a component i in the liquid phase of the composition, .DELTA.H.sub.i.sup.f is the heat of fushion (cal.mol.sup.-1) of the component i, T.sub.i.sup.f is the melting point (K) of the component i, T is the temperature (K) of the system, and R is the gas constant (cal.mol.sup.-1.K.sup.-1).

Abstract: An oil-impregnated capacitor made by winding at least one plastic film impregnated with an electrical insulating oil comprising 1-phenyl-1-methylphenylethane in which 1-phenyl-1-(4-methylphenyl)ethane and 1-phenyl-1-(2-methyl)ethane are present in amounts of not less than 70 percent and not more than 15 percent, respectively, based on the total weight of the 1-phenyl-1-methylphenylethane.

Abstract: An electrical appliance impregnated with a curable impregnant composition comprising as the curable ingredient at least one aromatic olefin and/or diolefin having a plurality of condensed- or noncondensed-type aromatic rings.

Abstract: An improved electrical insulating oil and oil-filled electrical appliances impregnated therewith. The electrical insulating oil has a low viscosity, low pour point and other excellent electrical characteristics and it comprises an isomer mixture of dibenzylbenzenes in which the quantity of p-dibenzylbenzene is not more that 10% by weight and the weight ratio of m-dibenzylbenzene/o-dibenzylbenzene is not lower than 3.

Abstract: An oil-filled capacitor which can be made small in size and has excellent electrical characteristics. The capacitor of the present invention is characterized in that it is made by impregnating a film-wound capacitor element with 1-phenyl-1-(benzylphenyl)ethane, at least a part of the dielectric material of said capacitor being made of a plastic film.

Abstract: An electrical insulating oil which can be produced easily at low cost, scarcely contains undesirable components of tarry substance, unsaturated compounds and carbonyl compounds, does neither swell nor dissolve plastic materials, and has excellent electrical properties. The electrical insulating oil is characterized in that it comprises a fraction having boiling points in the range of 270.degree. to 350.degree. C. which is prepared by distilling the heavier products obtained from the process for producing ethyltoluene by alkylating toluene with ethylene in the presence of synthetic zeolite catalyst. Included also in the present invention are oil-filled electrical appliances that are produced by impregnating them with the above insulating oil.