There is provided an insulated electric wire formed by covering a rectangular conductor wire having a rectangular cross-sectional shape with an insulating film. The insulating film is formed of an inner layer covering a surface of the rectangular conductor wire, and an outer layer covering a surface of the inner layer. A thickness (t.sub.1) of a section of the inner layer, which covers one short side of two facing short sides of the same length of a rectangular cross section of the rectangular conductor wire, is greater than a thickness (t.sub.2) (including that t.sub.2=0) of a section of the inner layer which covers the other short side. An elastic modulus and/or a yield stress of the inner layer are less than an elastic modulus and/or a yield stress of the outer layer.

There is provided an insulated electric wire formed by covering a rectangular conductor wire having a rectangular cross-sectional shape with an insulating film. The insulating film is formed of an inner layer covering a surface of the rectangular conductor wire, and an outer layer covering a surface of the inner layer. A thickness (t.sub.1) of a section of the inner layer, which covers one short side of two facing short sides of the same length of a rectangular cross section of the rectangular conductor wire, is greater than a thickness (t.sub.2) (including that t.sub.2=0) of a section of the inner layer which covers the other short side. An elastic modulus and/or a yield stress of the inner layer are less than an elastic modulus and/or a yield stress of the outer layer.

Provided is a method for producing a material that suppresses a decrease in the life of an insulation against surge voltage, that is, a material that provides a long dielectric breakdown lifetime. The method is a method for producing a fullerene-derivative-containing resin composition containing a fullerene derivative and a resin that has an affinity for a polar solvent, including: a step (I) of dispersing a fullerene derivative in a polar solvent; and a step (II) of mixing the polar solvent in which the fullerene derivative is dispersed with a resin that has an affinity for the polar solvent.

Provided is a method for producing a material that suppresses a decrease in the life of an insulation against surge voltage, that is, a material that provides a long dielectric breakdown lifetime. The method is a method for producing a fullerene-derivative-containing resin composition containing a fullerene derivative and a resin that has an affinity for a polar solvent, including: a step (I) of dispersing a fullerene derivative in a polar solvent; and a step (II) of mixing the polar solvent in which the fullerene derivative is dispersed with a resin that has an affinity for the polar solvent.

The present invention provides an amide acid oligomer which has specific composition and which is capable of providing a cured product having excellent physical properties, in particular, an excellent glass transition temperature, etc.

The present invention provides an amide acid oligomer which has specific composition and which is capable of providing a cured product having excellent physical properties, in particular, an excellent glass transition temperature, etc.

A silica sol dispersed in a nitrogen-containing solvent and a silica-containing resin composition containing a nitrogen atom-containing polymer. A silica sol including silica particles containing aluminum atoms and having an average primary particle diameter of 5 to 100 nm, the silica particles being dispersed in a nitrogen-containing solvent, wherein the aluminum atoms are bonded to the surfaces of the silica particles in an amount in terms of Al.sub.2O.sub.3 of 800 to 10,000 ppm/SiO.sub.2. The silica particles are bonded to a silane compound or a hydrolysate of the silane compound. The nitrogen-containing solvent is an amide solvent. The nitrogen-containing solvent is dimethylacetamide, dimethylformamide, N-methylpyrrolidone, or N-ethylpyrrolidone. The insulating resin composition includes the silica sol and a nitrogen-containing polymer. The nitrogen-containing polymer is polyimide, polyamide, polyamic acid, polyamideimide, polyetherimide, or polyesterimide. An insulation-coated conductor wire produced by insulation coating of a conductor wire with the insulating resin composition.

A silica sol dispersed in a nitrogen-containing solvent and a silica-containing resin composition containing a nitrogen atom-containing polymer. A silica sol including silica particles containing aluminum atoms and having an average primary particle diameter of 5 to 100 nm, the silica particles being dispersed in a nitrogen-containing solvent, wherein the aluminum atoms are bonded to the surfaces of the silica particles in an amount in terms of Al.sub.2O.sub.3 of 800 to 10,000 ppm/SiO.sub.2. The silica particles are bonded to a silane compound or a hydrolysate of the silane compound. The nitrogen-containing solvent is an amide solvent. The nitrogen-containing solvent is dimethylacetamide, dimethylformamide, N-methylpyrrolidone, or N-ethylpyrrolidone. The insulating resin composition includes the silica sol and a nitrogen-containing polymer. The nitrogen-containing polymer is polyimide, polyamide, polyamic acid, polyamideimide, polyetherimide, or polyesterimide. An insulation-coated conductor wire produced by insulation coating of a conductor wire with the insulating resin composition.

There is provided herein a resin composition comprising:

(i) a silane coupling agent of the general formula (I):

##STR00001##

as described herein, and

(ii) at least one resin which is interactive with one or more of the R.sup.1, R.sup.2 and X groups of silane coupling agent (i).

There is provided herein a resin composition comprising:

(i) a silane coupling agent of the general formula (I):

##STR00001##

as described herein, and

(ii) at least one resin which is interactive with one or more of the R.sup.1, R.sup.2 and X groups of silane coupling agent (i).