Thermally activatable, fast curing adhesive coating

Abstract

The present invention relates to a thermally activatable adhesive composition for use in a method for producing a stack of metal sheets from glued together sheet metal components, the use of the adhesive composition in a method for producing a stack of metal sheets from glued together sheet metal components, the method for producing a stack of metal sheets from glued together sheet metal components, a sheet metal component coated with the adhesive composition, and a stator or rotor core containing one or more of such sheet metal components.

Claims

1. A thermally activatable adhesive compound to use in a method for producing a stack of metal sheets from glued together sheet metal components containing an aqueous dispersion comprising: 100 parts by weight of an epoxy resin; 4 to 8 parts by weight of a latent curing agent; 4 to 10 parts by weight of a latent accelerator; and water, wherein the curing time is at most 5 seconds.

2. A thermally activatable adhesive compound according to claim 1, further containing: 2 to 12 parts by weight of one or more anti-corrosion additives of zinc aluminum molybdate phosphates and/or strontium aluminum polyphosphates.

3. The adhesive compound according to claim 1, further containing: 5 to 15 parts by weight of one or more insulation additives of kaolin and/or mica.

4. The adhesive compound according to claim 1, further containing: 0.2 to 8 parts by weight of absorption additives of carbon blacks and/or iron oxide.

5. The adhesive compound according to claim 1, further containing one or more of the following: fillers, dispersants and film-forming agents.

6. The adhesive compound according to claim 1, characterized in that the epoxy resin is an aqueous dispersion of bisphenol A epoxy resin.

7. The adhesive compound according to claim 1, characterized in that the latent curing agent contains a dicyandiamide, a BF.sub.3 amine complex or a combination thereof.

8. The adhesive compound according to claim 1, characterized in that the latent accelerator contains an urea derivative and/or an imidazole.

Description

EXAMPLES

(1) Experiments were conducted with two products according to the invention (examples 1 and 2) and two comparable prior art products (Voltatex 1175W from Axalta and Dispercoll U 8755 from Bayer Materials Science).

(2) Experimental Conditions:

(3) Application of the adhesive to an electrical sheet steel, sheet thickness 0.3 mm

(4) Layer thickness after drying process: 5-6 m

(5) Sample geometry: 25 mm100 mm

(6) Testing of lap shear strength based on DIN EN 1465

(7) Overlapping length: 12.5 mm

(8) Joining the samples in the hot press: 200 C., 1 s (see example 1)

(9) or joining the samples by means of NIR radiation (0.3 s) (see example 2)

(10) TABLE-US-00001 Baked enamel PU dispersion (Voltatex (Dispercoll Adhesive designation: 1175W) U8755) Example 1 Example 2 EpiRez 5108-W-60 100 parts 100 parts (bisphenol A epoxy resin) Dyhard 100 SF 6 parts 6 parts (dicyandiamide) Dyhard URAcc57 (urea 8 parts 8 parts derivative) Heucophos SAPP 8 parts 8 parts (strontium aluminum polyphosphate hydrate) Kaolin 15 parts 15 parts Iron oxide 2 parts Results: Joining process Hot press, Hot press, Hot press, NIR radiation, 200 C., 1 s 200 C., 1 s 200 C., 1 s 0.3 s, joining at RT Lap shear strength 0.5 MPa 1.7 MPa 6.1 MPa 6.3 MPa Lap shear strength 0 MPa 0 MPa 2.1 MPa 1.2 MPa at 190 C.

(11) The experimental data proves that an adhesive compound according to the invention results in a lap shear strength of the obtained sheet metal composite that cannot be achieved by adhesive compounds of the prior art with the same activation time.