Powder coating compositions capable of having a substantially non-zinc containing primer

Patent metadata

Field	Value
Publication number	US-10550283-B2
Application number	US-201816002093-A
Country	US
Kind code	B2
Filing date	Jun 7, 2018
Priority date	Jul 29, 2009
Publication date	Feb 4, 2020
Grant date	Feb 4, 2020

Abstract

Corrosion and chip-resistant coatings for high tensile steel components, such as automotive coil springs, can be formed from a coating composition comprising a primer having an epoxy resin with the proviso that the epoxy resin does not have an EEW of about 860 to about 930, a polyhydroxyl functional phenolic curing agent having a HEW of about 200 to about 500, and a platy filler. The primer contains less than 20 wt % zinc. The topcoat includes an epoxy resin having an epoxy equivalent weight of about 450 to about 1400, an elastomer-modified epoxy resin having an epoxy equivalent weight of about 1000 to about 1600, a foaming agent and a reinforcing fiber.

First claim

I claim:

1. A steel alloy coated by a composition comprising an epoxy thermoset primer comprising:
a corrosion resistant primer formed from an epoxy thermoset primer composition comprising:
an epoxy resin with the proviso that the epoxy resin does not have an EEW of 860 to 930;
a polyhydroxyl functional phenolic curing agent having a HEW of 200 to 500; and
a platy filler;

wherein the epoxy thermoset primer is substantially zinc-free; and
a topcoat,
the topcoat comprising
an epoxy thermoset topcoat composition that includes:
an epoxy resin having an EEW of 450 to 1400;
an elastomer-modified epoxy resin having an EEW of 1000 to 1600; and
a foaming agent that is p,p′-oxybis(benzenesulfonylhydrazide), activated azodicarbonamide based compositions, or a p-toluenesulfonylhydrazide based foaming agents, and

a reinforcing fiber;
wherein the epoxy resin in the epoxy resin thermoset topcoat composition is a bisphenol A epoxy resin present in an amount from 10 to 85 parts per hundred resin.

2. The steel alloy of claim 1 , wherein the epoxy topcoat further comprises a carboxyl functional polyester resin with an acid number of 25 to 85 mg KOH/g.

3. The steel alloy of claim 1 , wherein the epoxy resin of the epoxy thermoset primer composition has an EEW of 730 to 1400, with proviso that the epoxy resin of the epoxy thermoset primer composition does not have an EEW of 860 to 930 or wherein the epoxy resin of the epoxy thermoset primer composition has an EEW of between 780 and 900 with the proviso that the epoxy resin of the epoxy thermoset primer composition does not have an EEW of between 860 and 930.

4. The steel alloy of claim 1 , wherein the epoxy resin of the epoxy thermoset primer composition has an EEW of 730 to 820, an EEW of between 1250 and 1400, or an EEW of between 750 and 850.

5. The steel alloy of claim 1 , wherein the curing agent further comprises a 2-methylimidazole cure accelerator.

6. The steel alloy of claim 1 , wherein the platy filler comprises complex aluminosilicate (mica), magnesium silicate (talc), or a combination thereof.

7. The steel alloy of claim 6 , wherein the platy filler includes complex aluminosilicate (mica) present in an amount from 10 to 40 phr and has a median particle size of from 10 to 35 microns.

8. The steel alloy of claim 6 , wherein the platy filler further includes glass flakes having a nominal thickness of 1.3-2.3 microns.

9. The steel alloy of claim 6 , wherein the platy filler includes magnesium silicate (talc) present in an amount of from 10 to 40 phr and with a median particle size of from 10 to 35 um.

10. The steel alloy of claim 1 , wherein the elastomer-modified epoxy resin comprises a bisphenol A epoxy resin present in an amount from 5 to 35 pans per hundred resin.

11. The steel alloy of claim 1 , wherein the epoxy thermoset primer contains zero zinc.

12. The steel alloy of claim 1 , wherein the reinforcing fiber comprises aluminosilicate, calcium metasilicate (wollastonite), aramid, carbon, or a combination thereof.

Assignees

• Akzo Nobel Coatings Int Bv
• Akzo Nobel Coating Int B V

Inventors

• Lucas Chad

Classifications

• C09D5/031

  characterised by particle size or shape · CPC title

• C09D7/70

  characterised by shape, e.g. fibres, flakes or microspheres · CPC title

• C08L67/00

  Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain (of polyester-amides C08L77/12; of polyester-imides C08L79/08); Compositions of derivatives of such polymers · CPC title

• C09D5/106 Primary

  containing Zn · CPC title

• C09D163/00 Primary

  Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins · CPC title