Acid zinc sulfate metal pretreatment
AssigneeFreiborne Industries, Inc.
InventorsRobert R. Roelofs, Jennifer Kim
Life of this patent
Estimating the term…
Abstract
Disclosed is a phosphate-free aqueous acidic conversion coating comprising zinc sulfate and sulfuric acid. The conversion coating finds special use as a conversion coating to metal substrates prior to application of a cold forming lubricant or prior to application of a paint. The conversion coatings according to the present disclosure avoid the issues associated with phosphate containing conversion coatings but provide similar benefits to phosphate-based conversion coatings. Optional components of the conversion coating solutions include one or more of pH adjustment neutralizers, coating stabilizers, coating accelerators, coating refiners, etchants, paint adhesion promotors and mixtures thereof. In an additional option, manganese oxide can be used in place of zinc oxide.
Claims20
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.
A phosphate-free aqueous acidic conversion coating solution for metal substrates comprising:
- zinc oxide and sulfuric acid;
- said conversion coating solution having a pH of from 4.0 to 6.0, a coating refiner, at least one paint adhesion promoter in a positive amount, and optionally comprising one or more of a pH adjustment neutralizer, a coating concentrate, stabilizer, a coating accelerator, a coating refiner, an etchant, and mixtures thereof, and
- wherein the at least one adhesion promotor is present in an amount of from 0.5 to 2.0 mM and wherein the adhesion promotor is selected from the group consisting of hydroxylamine sulfate;
- m-nitrobenzene sulfonate sodium salt;
- sodium nitrate;
- sodium chlorate;
- 3-aminobenzene sulfonic acid;
- and mixtures thereof.
Dependencies are inferred from the claim text.