US 12,291,658 B2
Electrical steel strip or sheet, method for producing such an electrical steel strip or sheet, and lamination stack made therefrom
Ronald Fluch, Linz (AT); and Timothy Keppert, Linz (AT)
Assigned to voestalpine Stahl GmbH, Linz (AT)
Appl. No. 17/056,709
Filed by voestalpine Stahl GmbH, Linz (AT)
PCT Filed May 20, 2019, PCT No. PCT/EP2019/063010
§ 371(c)(1), (2) Date Nov. 18, 2020,
PCT Pub. No. WO2019/219983, PCT Pub. Date Nov. 21, 2019.
Claims priority of application No. 18173378 (EP), filed on May 18, 2018.
Prior Publication US 2021/0309894 A1, Oct. 7, 2021
Int. Cl. C09J 163/00 (2006.01); B32B 7/12 (2006.01); B32B 15/01 (2006.01); B32B 37/12 (2006.01); C09J 7/28 (2018.01); C09J 7/35 (2018.01); H01F 1/18 (2006.01)
CPC C09J 163/00 (2013.01) [B32B 7/12 (2013.01); B32B 15/011 (2013.01); B32B 37/1207 (2013.01); C09J 7/28 (2018.01); C09J 7/35 (2018.01); H01F 1/18 (2013.01); B32B 2037/1215 (2013.01); C09J 2301/304 (2020.08); C09J 2463/00 (2013.01)] 21 Claims
 
1. An electrical steel strip or sheet comprising:
at least one thermo-hardenable, water-based hot-melt adhesive varnish layer provided on one flat side of the electrical steel strip or sheet, wherein the at least one thermo-hardenable, water-based hot-melt adhesive varnish layer comprises an epoxy resin or a mixture of epoxy resins, at least one hardener, and a pre-cross-linking agent that bonds with the epoxy resin or with the mixture of epoxy resins, and wherein the pre-cross-linking agent is an organic triamine, and wherein percentages by weight of the pre-cross-linking agent and the epoxy resin or mixture of epoxy resins in the thermo-hardenable, water-based hot-melt adhesive varnish layer satisfy the following relation:

OG Complex Work Unit Math
where
X stands for a number from 1.6 to 28.9, and
M stands for molar mass;
wherein the thermo-hardenable, water-based hot-melt adhesive varnish layer contains:
35 to 55% by weight of the epoxy resin or mixture of epoxy resins with an average molar mass of 1500 to 2000 g/mol;
2 to 10% by weight of the hardener; and
0.1 to 2% by weight of the organic triamine as the pre-cross-linking agent with an average molar mass of 350 to 550 g/mol, and
wherein, when the thermo-hardenable, water-based hot-melt adhesive varnish layer is dried, the dried thermo-hardenable, water-based hot-melt adhesive varnish layer contains:
75 to 92.8% by weight of the epoxy resin or mixture of epoxy resins with an average molar mass of 1500 to 2000 g/mol,
4 to 24.8% by weight of the hardener, and
0.2 to 4% by weight of the organic triamine as the pre-cross-linking agent with an average molar mass of 350 to 550 g/mol.