	US 12,188,130 B2
	Acid zinc sulfate metal pretreatment
Robert R. Roelofs, Allen Park, MI (US); and Jennifer Kim, Sterling Heights, MI (US)
Assigned to Freiborne Industries, Inc., Pontiac, MI (US)
Filed by Freiborne Industries, Inc., Pontiac, MI (US)
Filed on Jul. 22, 2019, as Appl. No. 16/518,113.
Claims priority of provisional application 62/701,961, filed on Jul. 23, 2018.
Prior Publication US 2020/0024743 A1, Jan. 23, 2020
Int. Cl. C23C 22/48 (2006.01); C23C 22/50 (2006.01); C23C 22/52 (2006.01); C23C 22/56 (2006.01); C23C 22/00 (2006.01)

CPC C23C 22/50 (2013.01) [C23C 22/52 (2013.01); C23C 22/56 (2013.01)]

20 Claims

1. A phosphate-free aqueous acidic conversion coating solution for metal substrates comprising:

zinc oxide and sulfuric acid; and

said conversion coating solution having a pH of from 4.0 to 6.0, a coating refiner in a positive amount of up to 10 mM, and optionally comprising one or more of a pH adjustment neutralizer in a positive amount, a coating concentrate stabilizer, a coating accelerator, an etchant, a paint adhesion promotor and mixtures thereof; and

wherein the coating refiner is selected from the group consisting of a trisodium salt of N-(2-hydroxyethyl) ethylenediamine; N,N′,N′ triacetic acid; a sodium salt of L-glutamic acid; N,N-diacetic acid; nitrilotrisacetic acid; and mixtures thereof.