An insulation film composition for a grain-oriented electrical steel sheet according to an exemplary embodiment of the present invention includes 10-50 parts by weight of metal silicate or organic silicate, 20-70 parts by weight of inorganic nanoparticles and 0.1-20 parts by weight of cobalt hydroxide. The insulation film composition can further include 10-50 parts by weight of metal phosphate, and/or 5-30 parts by weight of inorganic nanoparticles having a particle diameter of 1 nm to less than 10 nm, and/or inorganic nanoparticles having a particle diameter of 10 to 100 nm and/or 0.1-20 parts by weight of chromium oxide.

A non oriented electrical steel sheet consists of a silicon steel sheet and an insulation coating. The silicon steel sheet contains Si, Al, and Mn as chemical composition, and an alignment degree to {5 5 7}<7 14 5> orientation in a central area along a thickness direction of the silicon steel sheet is 12 to 35.

A coating agent for forming a grain-oriented electrical steel sheet coating able to form an aluminum borate coating high in adhesion and large in tension and a method for manufacturing the grain-oriented electrical steel sheet are provided. The coating agent for forming a grain-oriented electrical steel sheet coating of the present invention comprises an aluminum source containing aluminum oxide and/or an aluminum oxide precursor compound, a boron source containing a borate of an alkali metal, and silicon oxide and/or a silicon oxide precursor in an amount, converted to silicon oxide, of 5 mass % or more and 10 mass % or less with respect to a total solids concentration of the aluminum source and boron source, the aluminum source and the boron source contained so that, by molar ratio, Al/B: 0.5 to 2.0, a solids concentration of a total of the aluminum source and the boron source being 20 mass % or more and 38 mass % or less, and pH being 2.0 or more and 6.0 or less.

A coating composition for an electrical steel sheet including an epoxy resin, an epoxy resin by latent curing agent, and a thermoplastic elastomer, wherein the thermoplastic elastomer has a melting point of 100° C. or higher and 200° C. or lower and a bending elastic modulus of more than 5 MPa and 100 MPa or less, and wherein the amount of the thermoplastic elastomer with respect to a total amount of 100 parts by mass of the epoxy resin and the epoxy resin by latent curing agent is 10 parts by mass or more and less than 40 parts by mass.

An electrical steel sheet used for a laminated core is an electrical steel sheet including an insulation coating 3 on a surface of a base steel sheet 2, the insulation coating being coated with a coating composition for an electrical steel sheet. The coating composition for an electrical steel sheet contains an epoxy resin, a first curing agent including an alkylphenol, and a second curing agent including either one or both of a phenol resol resin and a phenol novolac resin formulated in specific proportions.

An electrical steel sheet used for a laminated core is an electrical steel sheet including an insulation coating 3 on a surface of a base steel sheet 2, the insulation coating being coated with a coating composition for an electrical steel sheet. The coating composition for an electrical steel sheet contains an epoxy resin, a first curing agent including an alkylphenol, and a second curing agent including either one or both of a phenol resol resin and a phenol novolac resin formulated in specific proportions.

This coating composition for an electrical steel sheet contains an epoxy resin, a phenolic curing agent (A) and one or more amine-based curing agents (B) selected from the group consisting of an aromatic amine and dicyandiamide, the amount of the phenolic curing agent (A) is 1 to 40 parts by mass with respect to 100 parts by mass of the epoxy resin, and the amount of the amine-based curing agents (B) is 0.5 to 5 parts by mass with respect to 100 parts by mass of the epoxy resin.

This coating composition for an electrical steel sheet contains an epoxy resin, a phenolic curing agent (A) and one or more amine-based curing agents (B) selected from the group consisting of an aromatic amine and dicyandiamide, the amount of the phenolic curing agent (A) is 1 to 40 parts by mass with respect to 100 parts by mass of the epoxy resin, and the amount of the amine-based curing agents (B) is 0.5 to 5 parts by mass with respect to 100 parts by mass of the epoxy resin.

A grain-oriented electrical steel sheet includes: a steel sheet and optionally an insulation coating formed on the steel sheet, in which, in a case where a heat treatment of performing retention at 800° C. for 2 hours is performed, regarding a time-magnetostriction waveform (t−λ waveform) when magnetized to 1.7 T, a peak value of a difference waveform obtained by subtracting the time-magnetostriction waveform after the heat treatment from the time-magnetostriction waveform before the heat treatment is 0.01×10.sup.−6 or more and 0.20×10.sup.−6 or less, and a difference obtained by subtracting an iron, loss before the heat treatment from an iron loss after the heat treatment is 0.03 W/kg or more and 0.17 W/kg or less.

A grain-oriented electrical steel sheet of the present invention has a base steel sheet, an amorphous oxide layer formed on the base steel sheet, and a tension-insulation coating formed on the amorphous oxide layer, in which the base steel sheet contains, as a chemical composition, by mass %, C: 0.085% or less, Si: 0.80 to 7.00%, Mn: 1.50% or less, acid-soluble Al: 0.065% or less, S: 0.013% or less, Cu: 0 to 0.80%, N: 0 to 0.012%, P: 0 to 0.50%, Ni: 0 to 1.00%, Sn: 0 to 0.30%, and Sb: 0 to 0.30%, a remainder is Fe and an impurity, a surface glossiness Gs20(A) in a direction parallel to a rolling direction is 2.0 to 70, and a surface glossiness Gs20(B) in a direction perpendicular to the rolling direction is 2.0 to 70.