Zinc-free anticorrosives: Challenges and latest · PDF fileField Rusting . Adhesion Accelerated ... • Stabilizing metal cations by chelating effect on iron’ Ion scavenger ... Ion-scavenging,

Zinc-free anticorrosives: Challenges and latest developments Lars Kirmaier, Heubach GmbH

Slide 2 / 46 European Coatings CONFERENCE „Protective coatings“, 12. – 13. September 2013 Heubach GmbH, Lars Kirmaier

Why change a winning team?

Driving force behind going zinc-free

What can we offer?

Orthophosphates, Polyphosphates, Silicas How about performance?

Modified acrylic dispersion with calcium phosphate

Solvent based alkyd system with calcium phosphate

Solvent based 2K PU with calcium aluminum

polyphosphate

Coil coating primer with polyphosphate synergists

Powder primer with calcium modified silica

Solvent-free UV primer with calcium modified silica Where are we going?

Agenda

Slide 3 / 46 European Coatings CONFERENCE „Protective coatings“, 12. – 13. September 2013

Zinc phosphate- Labelling and classification


Zinc price development

Zinc Price 1992 - 2009 (Euro)

200920082007200220012000 2004200319991998199719961995199419931992 2005 200640,00 €

60,00 €

80,00 €

100,00 €

120,00 €

140,00 €

160,00 €

180,00 €

200,00 €

220,00 €

240,00 €

260,00 €

280,00 €

300,00 €

320,00 €

340,00 €


Alternatives to zinc- what do we have?


Requirements:

Modified non-zinc metal complex

Anodic inhibition and barrier properties

Universal applicability

Easy handling

Stability in a broad range of resins

Price stability (non LME metal like Zn)

The wish list

What’s the problem?

Zinc(II) compounds are amphoteric with a special solubility behaviour in acidic and basic environments that most of the alternate metals don’t show!


Zinc-free anticorrosive pigments:

Orthophosphates

Calcium phosphate

Mid-level performance and alternative to zinc phosphate

Polyphosphates:

Calcium aluminum polyphosphate silicate hydrate

Strontium aluminum polyphosphate hydrate

High-performance pigments, alternative to zinc and

chromate containing anticorrosives

Ion-exchanger:

Modified silica gel

High-performance pigment for demanding coating systems

Alternatives to zinc?


Corrosion protection with zinc-free orthophosphates

• Anodic passivation- phosphate layers • Precepetation of M(OH)x (barrier)

(M: Ca, Sr, Mg….)


Challenge: Long-term performance

0

10

20

30

40

50

60

70

80

90

100

Start 0,5 1 1,5 2 2,5 3 3,5 4 4,5 5 5,5 6Time (weeks)

Perf

orm

ance

zinc orthophosphates zinc-free orthophosphates


Formulating with zinc-free anticorrosives

• Is the PVC optimized, find the optimum CPVC/PVC!

• Morphology of extenders and fillers (platy, lammellar….)!

• Mind the Additive package (hydrophobic)!

• If you do not match the desired protective performance:

Make use of benefits of different pigments by combinations!

’ Synergy!


Zn-free water based industrial primer

Primer: Mod. acrylic dispersion DFT: 80 microns Substrate: CRS ST 1205 Application: Air Spray Drying: 14d RT/ 2h 50°C


Undercutting

Blistering

Field Rusting

Adhesion

Accelerated Weathering Tests


Control Zinc phosphate Calcium phosphate

144h salt spray test acc. to DIN EN ISO 9227/ ASTM B 117-11 on CRS



Control Zinc phosphate Calcium phosphate

648h humidity test acc. to ISO 6270 / ASTM D 2247-02 on CRS



• Deposition of polyphosphate films on the metal surface

• Stabilizing metal cations by chelating effect on iron’ Ion scavenger

• Dissociation back to orthophosphates, anodic passivation

• Precepetation of M(OH)x (barrier)

(M: Ca, Sr, Mg….)

Corrosion Protection with zinc-free Polyphosphates

↔


Special modification of SAPP, for application like coil coating etc.

Altered solubility behavior due to the basic reacting metal oxides compared to amphoteric zinc


SRPP


SAPP

I: Modified polyphosphate hydrates

II: Modified polyphosphate silicate hydrates

Altered solubility behavior due to the calcium which is not chemically amphoteric as compared to zinc, in combination with the fixed active components

Calcium aluminum polyphosphate silicate hydrate

CAPP

Corrosion Protection with zinc-free Polyphosphates


Zn-free solvent based industrial primer

Primer: 2K-Polyurethane DFT: 60 microns Substrate: HDG Application: Air Spray Drying: 5 weeks RT/ 2h 50°C


1406h salt spray test acc. to DIN EN ISO 9227/ ASTM B 117-11 on HDG

Control Calcium phosphate CAPP

Zinc-free polyphosphates versus orthophosphates



Primer: Epoxy ester DFT: 40 microns Substrate: CRS ST 1205 Application: Air Spray Drying: 2 weeks RT/ 2h 50°C



Control Mod. Zinc phosphate CAPP

Zinc-free polyphosphates versus zinc orthophosphates


Synergy may be defined as two or more agents working together to produce a result not obtainable by any of the agents independently.

1+1=3

Using synergies- Let‘s work together

Higher efficiency in

anodic and cathodic areas


Using zinc-free synergies in Coil Coating primers

Primer: High molecular polyester (primer) Top Coat: Polyester DFT: Primer: 6-8 microns, Topcoat: 20-24 microns Substrate: Zincalume, pre-treated Cr-free HDG, pre-treated Cr-free Application: Doctor blade PCM: 232°C/450°F for primer and topcoat


T-Bend AS/NZS 2728:2007


1120h salt spray test acc. to DIN EN ISO 9227/ ASTM B 117-11 on zincalume



Strontium chromate SRPP/CAPP 1:1

1120h salt spray test acc. to DIN EN ISO 9227/ ASTM B 117-11 on zincalume



T-Bend ECCA –T8 [1996]

1t bend

3t bend

Vertical scribe

Horizontal scribe













Modified silica pigments

• Formation of a passive layer (barrier)

• Adsorption of corrosion stimulators


Zinc-free powder primer

Primer: Carboxylated polyester powder DFT: 100 microns Substrate: CRS ST 1205 Application: Korona Baking: 20 mins at 180°C


2520h salt spray test acc. to DIN EN ISO 9227/ ASTM B 117-11 on steel

Control Mod. zinc phosphate CTF

Zinc-free powder primer


Zinc-free UV primer

Primer: 100% Epoxy-Acrylate DFT: 30 microns Substrate: CRS ST 1205, HDG UV lamp: Mercury lamp 120W/cm Application: Roller Coater



Control Zinc phosphate Mod. Zinc

phosphate

CTF

Zinc-free UV primer



Control Zinc phosphate Mod. Zinc

phosphate

CTF

Zinc-free UV primer


• Replacing zinc in anticorrosive pigments while

maintaining long-term performance is a challenge but

possible

• Using synergies by pigment combinations helps to

improve the overall performance (2-way synergy)

Novel multiphase pigments with mixed

inhibitive effect (1-way synergy)

New organic surface functionalizion

Ion-scavenging, complexation, coupling

Conclusions so far and new approaches

NEW!


Zinc-free synergistic pigment

Primer: Water based acrylic dispersion DFT: 70 microns Substrate: CRS ST 1205 Application: Air spray Drying: 21d RT/ 2h 50°C




Control Calcium phosphate Zinc-free synergistic pigment

Mod. zinc phosphate


552h salt spray test acc. to ISO 6270 / ASTM D 2247-02 on CRS


Control Calcium phosphate Zinc-free synergistic pigment

Mod. zinc phosphate


Zinc-free surface functionalized pigment

Primer: Solvent based short-oil alkyd DFT: 70 microns Substrate: CRS ST 1205 Application: Air spray Drying: 21d RT/ 2h 50°C


Control Ca base pigment Functionalized Ca pigment




Zinc-free Mg base pigment

Functionalized Mg pigment

Note: Surface modification has to be well matched to the base pigment!

No improvement!



Primer: Solvent based short-oil alkyd DFT: 50 microns Substrate: CRS ST 1205 Application: Air spray Drying: 21d RT/ 2h 50°C

Organophilized pigment



Control Calcium phosphate Zinc phosphate molybdate

Organophilized zinc-free pigment




Control Calcium phosphate Zinc phosphate molybdate

Organophilized zinc-free pigment



Future targets:

Learn more about synergistic effects

Enhance universal applicability

Find the multi-tool of corrosion protection

Conclusions so far

Klicker / pixelio.de

Documents

Zinc-free anticorrosives: Challenges and latest · PDF fileField Rusting . Adhesion Accelerated ... • Stabilizing metal cations by chelating effect on iron’ Ion scavenger ... Ion-scavenging,