Electrical steel sheet, laminated core and rotating electric machine

An electrical steel sheet, comprising:

• a base steel sheet comprising, in mass %:
• Si:
• 2.5% to 4.5%,
• Al:
• 0.001% to 3.0%,
• Mn:
• 0.05% to 5.0%, and
• a remainder of Fe and impurities;
• and
• an electrical insulation coating comprising an epoxy resin and an epoxy resin curing agent,
• wherein:
• at least a part of either or both surfaces of the base steel sheet is coated with the electrical insulation coating;
• the electrical insulation coating has an adhesive strength of 2.5 MPa or more, and exhibits electrical insulation performance with respect to the electrical steel sheet;
• wherein the adhesive strength is measured by a method in which two rectangular electrical steel sheet portions having a width of 30 mm and a length of 60 mm are cut out from the electrical steel sheet, and tip parts having a width of 30 mm and a length of 10 mm are made to overlap each other and adhered at a steel sheet temperature of 180° C., a pressure of 10 MPa, and a pressurization time of 1 hour to produce a sample, then a shear tensile strength of the sample is measured at an atmospheric temperature of 25° C. and a tensile speed of 3 mm/min to give a numerical value, and the numerical value divided by an adhesion area yields the adhesive strength;
• and
• a logarithmic decrement of the electrical insulation coating in a temperature range of 25 to 100° C. is 0.3 or less;
• and
• a difference between a peak temperature, in a temperature-logarithmic decrement curve, of the logarithmic decrement of the electrical insulation coating and a curing start temperature is less than 80° C., and a difference between a logarithmic decrement of the peak temperature and a logarithmic decrement of the curing start temperature is 0.1 or more,
• wherein the logarithmic decrement is measured by a rigid pendulum test using rigid pendulum tester RPT-3000W at a temperature rise rate of 10° C./sec according to ISO 12013-2, and
• wherein the curing start temperature is a singular point at which the absolute value of the slope decreases toward zero and then increases again in a decrease region after the peak temperature in a temperature-logarithmic decrement curve.

An electrical steel sheet, comprising:

• a base steel sheet comprising, in mass %:
• Si:
• 2.5% to 4.5%,
• Al:
• 0.001% to 3.0%,
• Mn:
• 0.05% to 5.0%, and
• a remainder of Fe and impurities;
• and
• an electrical insulation coating comprising an epoxy resin and an epoxy resin curing agent,
• wherein:
• at least a part of either or both surfaces of the base steel sheet is coated with the electrical insulation coating;
• the electrical insulation coating has an adhesive strength of 2.5 MPa or more, and exhibits electrical insulation performance with respect to the electrical steel sheet;
• wherein the adhesive strength is measured by a method in which two rectangular electrical steel sheet portions having a width of 30 mm and a length of 60 mm are cut out from the electrical steel sheet, and tip parts having a width of 30 mm and a length of 10 mm are made to overlap each other and adhered at a steel sheet temperature of 180° C., a pressure of 10 MPa, and a pressurization time of 1 hour to produce a sample, then a shear tensile strength of the sample is measured at an atmospheric temperature of 25° C. and a tensile speed of 3 mm/min to give a numerical value, and the numerical value divided by an adhesion area yields the adhesive strength;
• and
• a difference between a peak temperature, in a temperature-logarithmic decrement curve, of a logarithmic decrement of the electrical insulation coating and a curing start temperature is less than 80° C., and a difference between a logarithmic decrement of the peak temperature and a logarithmic decrement of the curing start temperature is 0.1 or more,
• wherein the logarithmic decrement is measured by a rigid pendulum test using rigid pendulum tester RPT-3000W at a temperature rise rate of 10° C./sec according to ISO 12013-2, and
• wherein the curing start temperature is a singular point at which the absolute value of the slope decreases toward zero and then increases again in a decrease region after the peak temperature in a temperature-logarithmic decrement curve.