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Intelligent modular concepts using nanoscale platelet pigments for protective coatings

Marc Entenmann, Heinz Greisiger, Roman Maurer, Henry Lehmann

Fraunhofer IPA, Stuttgart, Germany

A modular concept ofprotection with differentnanoscale protective pigmentsto enable the coating industryto adjust the protectionproperties

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© Fraunhofer IPA

Corrosion of construction metals causes losses in industrialized countries which are estimated to be approximately 3 % to 5 % of the respective gross domestic products

These losses originate from insufficient and non-durable corrosion protection of metals with coatings

3 to 4 separate layers are nowadays used for the corrosion protection of metals

The general trend in the coating industry can be described by the replacement of thick multilayer coatings with thin, less layer containing, highly efficient and functionalized coatings

The world wide demand for such new protective coatings will increase considerably, the more important future requirements concerning sustainability and reduction of material or maintenance costs will get

Status and needs for improvements

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© Fraunhofer IPA

To generate highly efficient and sustainable protective coatings, a concept is proposed, which is based on the combination of different functionalized nanoscale platelet pigments

These functionalized nanoscale platelet pigments should be able to integrate multifunctional properties: to improve the mechanical properties, provide photo-degradation stability, increase corrosion protection and endow barrier effects of the protective coatings

Because of the nanoscale character, the influence on colour or transparency of the coating layers should be considerably low

Through the modular character of the proposed concept, the different functionalized nanoscale platelet particles can be combined and the properties of the protective coatings can be adapted to the predominant environmental situation

The approach

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© Fraunhofer IPA

Comparison of the selected talcum components

Talcum d10 / µm d50 / µm d90 / µm d98 / µm PD / nm

LUZENAC 20M 3,6 11,6 30,3 53,3 60 - 121

Talc LP30 4,8 17,9 41,4 59,5 80

Mistron 754 G 2,7 11,9 31,4 45,2 80 - 91

Distributors Luzenac 20M provided from Rio Tinto Minerals Europe Talc LP30 provided from LITHOS Industrial Minerals GmbH Mistron 754 G provided from Rio Tinto Minerals Europe

Determination of properties Particle thickness characterized with SEM Particle size measurements performed with LSS

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Component Source % w/wAcronal Pro 80, 50 % BASF 52,46

BYK 022 Byk-Chemie 0,41

Surfynol 104 PA Air Products 0,41

Water - 8,56

BYK 347 Byk-Chemie 0,10

Dimethylaminoethanol (DMAE) - 0,26Butylglycole 1,74Heucophos ZMP Heubach 11,53Heucorin RZ Heubach 1,28Talcum 20 M 2 Luzenac 14,34Kronos 2310 Kronos 8,09CHE-Coat Ci LNF A4 Erbslöh 0,56Rheovis PU 1280 BASF 0,20

Simplified and optimized white primer testing formulation

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Testing of the primer formulations

The testing of the white primer formulations was performed with a dry layer thickness of 70 µm on steel panels

As steel substrates, 200 x 100 x 2,0 mm³ s DC 04 B steel panels, with round edges, sandblasted on both sides with a medium roughness of Rz20 - 30 µm were used

For testing of the barrier effect the talcum M2 was substituted with the organic inorganic modified/unmodified nanoscale equivalents

For testing of the UV-protection and barrier properties, formulations without the Kronos 2310 were tested and the talcum M2 was additionally exchanged with the new synthesized nanoscale organic and inorganic modified/functionalized talcum components

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© Fraunhofer IPA

Corrosion protection testing of organically modified nanoscale talcum LP30 in the white primer The coatings were charged with salt spray testing for 240 h

For the nanoscale talcum LP30 with different organic treatment excellent barrier and corrosion protection was observed

Talcum LP 30Talcum LP30 /epoxy-functional treatment Talcum LP30 / acrylic-functional treatment

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Corrosion protection testing of different inorganicallymodified talcum in the white primer

For the nanoscale talcum treated with TiO2 and Zn-phosphate (ZP), improved barrier and corrosion protection properties were obtained

The coating was charged 96 h with a 5 % w/w NaCl-solution on an infraction with a 0.5 mm drill as well as with a cut (scribe) at 23 °C

Talcum LP30 Talcum LP30 titania treatment Talcum LP30 zinc phosphate treatmentTalcum M2

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Corrosion protection testing of the less pigmented white primer formulations without TiO2

Nanoscale talcum modified with Zn-phosphate (ZP) showed excellent barrier-and corrosion protection properties in the less pigmented primer, after charging with thermocyclic loading, using a 5 % NaCl-solution

The coating was charged 48 h with a 5 % w/w NaCl-solution on a infraction with a 0.5 mm drill with thermocyclic loading from 23 °C to 70 °C

Talcum LP30 Talcum LP30 Ce-oxide treatmentTalcum M2 Talcum LP30 zinc phosphate treatment

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Scanning Kelvin Probe measurements (SKP) of the less pigmented white primer formulations without TiO2

The visual detectable corrosion effects could be confirmed by performing SKP-measurements

Nanoscale talcum modified with Zn-phosphate (ZP) showed less cathodic delamination outside the infraction

For nanoscale talcum modified with Zn-phosphate (ZP), less active anodic processes at the infraction point could be determined

The coating was charged 48h with a 5 % w/w NaCl-solution on a infraction with a 0.5 mm drill with thermocyclic loading from 23 °C to 70 °C

Talcum M2 samplewith anodic processes atthe infraction and greatcathodic delaminationarea around

1000 2000 3000 4000 5000 6000 7000 8000 9000

1000

2000

3000

4000

5000

6000-1,728-1,701-1,674-1,648-1,621-1,594-1,567-1,540-1,514-1,487-1,460-1,433-1,406-1,380-1,353-1,326-1,299-1,272-1,246-1,219-1,192

1000 2000 3000 4000 5000 6000 7000 8000 9000

1000

2000

3000

4000

5000

6000-1,706-1,682-1,658-1,634-1,610-1,586-1,562-1,538-1,514-1,489-1,465-1,441-1,417-1,393-1,369-1,345-1,321-1,297-1,273-1,249-1,225

1000 2000 3000 4000 5000 6000 7000 8000 9000

1000

2000

3000

4000

5000

6000

Y-Ac

hsen

titel

-0,9060-0,8935-0,8810-0,8686-0,8561-0,8436-0,8311-0,8186-0,8061-0,7937-0,7812-0,7687-0,7562-0,7437-0,7313-0,7188-0,7063-0,6938-0,6813-0,6688-0,6564

Talcum LP30 samplewith great cathodicdelamination area aroundthe infraction

Talcum LP30 / Ce-oxidetreatment with cathodicdelamination area aroundthe infraction

Talcum LP30 / zincphosphate treatmentwith less active anodicprocesses at the infractionand a less active cathodicdelamination area around.

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Impedance measurements of different inorganicallymodified talcum in the white primer

0 24 48 72 96 120 144 1681E8

1E9

1E10

impe

danc

e |Z

| at 0

,1H

z /

cm

²

duration of thermocyclic loading / h

MRP LP30 LP30(TiO2) LP30(ZP)

The improved corrosion protection of the nanoscale talcum modified with Zn-phosphate (ZP) could also be confirmed by performing impedance measurements

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Comparison of UV-absorption properties of inorgani-cally modified talcum LP30 in the white primer

For primer coatings without TiO2, containing inorganically modified nanoscale talcum LP30, higher transparency values from 500 nm to 2500 nm were obtained

Primer coatings without TiO2, containing inorganically modified nanoscale talcum LP30, showed only slightly increased UV-trans-parency, in comparison to the reference samples with TiO2

500 1000 1500 2000 25000

10

20

30

40

50

60

70

80

90

100

trans

mis

sion

/ %

wavelength / nm

MRP MLP MLPa MLPaT MLPaZO MLPaC

220 240 260 280 300 320 340-0,1

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

trans

mis

sion

/ %

wavelength / nm

MRP MLP MLPa MLPaT MLPaZO MLPaC

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UV-protection testing of inorganically and organically modified nanoscale talcum LP30 in white primer

For the nanoscale talcum LP30 treated with Ce-oxide, in the more transparent primer with reduced pigment concentration, improved UV-protection properties were obtained, in comparison to the reference systems which contains (MRP, MLP) or doesn´t contain TiO2 (MLPa) pigments

0,00

1,00

2,00

3,00

4,00

5,00

6,00

200h 400h 600h 800h 1000h

Δb value

Duration UV‐charging suntest / h

MRP

LP30

LP30 (TiO2)

LP30 (CeO2)

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© Fraunhofer IPA

Inorganic or organic, and especially a combination of both functionalizations of nanoscale talcum, successfully improve UV-absorption and protection as well as barrier- and corrosion protection properties

Primer formulations, for example with Ce-oxide treated nanoscale talcum, with higher transparency and lower pigmentation levels, but with comparable UV- and corrosion protection properties as the alternatives with additional 8 % titania pigmentation, could be achieved

For the samples charged with thermocyclic loading with NaCl-solution, it was only the transparent primer formulation with Zn-phosphate treated nanoscale talcum, with showed excellent corrosion protection

Conclusions

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© Fraunhofer IPA

This project was conducted at Fraunhofer Institute for Manufacturing Engineering and Automation IPA, coordinated by the Research Society for Pigments and Coatings (FPL e.V.) and financially funded via AiF by the German Federal Ministry of Economic Affairs and Energy

Our sincere thanks for supporting the protective coatings research in the project are given to our institute partners and especially to our industrial partners

FORSCHUNGSGESELLSCHAFTFÜR PIGMENTE UND LACKE E.V.

Acknowledgements

© Fraunhofer IPA

FORSCHUNGSGESELLSCHAFTFÜR PIGMENTE UND LACKE E.V.