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US 6,638,633 B1Granted
Solvent-resistant electrical steel sheet capable of stress relief annealing and process
AssigneeKawasaki Steel Corporation
InventorsYuka Komori, Katuro Yamaguchi, Keiji Sato
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Abstract
Electrical steel sheet can be produced by baking at low temperatures and is capable of stress relief annealing and has excellent solvent resistance and has an insulating coating containing substantially no chromium components harmful to environment; the electrical steel sheet has an insulating coating comprising a resin and an inorganic colloid which is silica, alumina or alumina-containing silica.
Claims22
An electrical steel sheet capable of stress relief annealing and having excellent solvent attack resistance comprising an electrical steel sheet,
- an insulating coating being low in phosphate content and being applied directly to said steel sheet,
- said insulating coating comprising a water-based resin selected from the group consisting of acryl, alkyd, polyolefin, styrene, vinyl acetate, epoxy, phenol, urethane, melamine resins and polyesters, and mixtures thereof,
- said resin comprising a single layer and having a glass transition temperature or a softening point of about 30-150° C.,
- and said single layer further comprising an inorganic colloid selected from the group consisting of silica, alumina, alumina-containing silica and mixtures thereof,
- the ratio of said colloid to said resin being 3-300 parts by weight, based upon solid weight, to 100 parts by weight of said resin,
- said resin of said insulating coating being applied directly to said steel sheet, and wherein said insulating coating contains substantially no hexavalent chromium component and can be baked at a low sheet steel temperature of about 50 to 250° C., and
- wherein, in the case the inorganic colloid comprises silica, said insulating coating further comprises at least one alkali metal selected from the group consisting of Li, Na, K in an amount of about 0.1 to 5 parts by weight expressed as M2O, wherein M is the alkali metal, per 100 parts by weight of silica expressed as SiO2, and
- said insulating coating has a sulfur content limited to 0-0.05 parts by weight of sulfur per 100 parts by weight of silica expressed as SiO2.
5 more elements
An electrical steel sheet capable of stress relief annealing and having excellent solvent attack resistance comprising:
- an electrical steel substrate;
- an insulating coating deposited and adhered in direct contact to said electrical steel substrate, said insulating coating consisting essentially of:
- a water-based resin selected from the group consisting of acryl, alkyd, polyolefin, styrene, vinyl acetate, epoxy, phenol, urethane, melamine resins and polyesters, and mixtures thereof, said water-based resin being formed as a single layer and having a glass transition temperature or a softening point of about 30-150° C.;
- and
- an inorganic colloid selected from the group consisting of silica, alumina alumina-containing silica, and mixtures thereof, wherein the ratio of said colloid to said resin in said single layer is 3-300 parts by weight, based upon solid weight, to 100 parts by weight of the resin, wherein
- said insulating coating is capable of effective baking at a sheet steel temperature of about 50 to 250° C., and
- wherein, in the case the inorganic colloid comprises silica, said insulating coating further comprises at least one alkali metal selected from the group consisting of Li, Na, K in an amount of about 0.1 to 5 parts by weight expressed as M2O, where M is the alkali metal, per 100 parts by weight of silica expressed as SiO2.
4 more elements
An electrical steel sheet capable of stress relief annealing and having excellent solvent attack resistance comprising:
- an electrical steel substrate;
- an insulating coating deposited and adhered in direct contact to said electrical steel substrate, said insulating coating comprising:
- a resin having a glass transition temperature or a softening point of 30 to 150° C. formed as a single layer, said single layer further comprising an inorganic colloid satisfying at least any one of the following (1) to (3) criteria:
- (1) said inorganic colloid comprises colloidal silica, and said single layer further comprises at least one alkali metal selected from the group consisting of Li, Na, K in an amount of about 0.1 to 5 parts by weight expressed as M2O, where M is the alkali metal, per 100 parts by weight of silica expressed as SiO2,
- (2) said inorganic colloid comprises colloidal alumina, and said single layer further comprises an organic acid as a stabilizing agent for alumina, and
- (3) said inorganic colloid comprises colloidal alumina-containing silica, and said single layer further comprises an organic acid as a stabilizing agent for alumina,
- and wherein said insulating coating contains no hexavalent chromium component and can be baked at a low sheet steel temperature of about 50 to 250° C.
4 more elements
Dependencies are inferred from the claim text.