Understanding the Mechanism of Improved Scratch and ... the Mechanism of Improved Scratch and...

Understanding the Mechanism of Improved Scratch and

Abrasion Resistance in Automotive Coatings using Surface-

Treated Nanoparticles

European Coatings Conference “Automotive Coatings”, Berlin, November 24th 2011, Dr. Michael Berkei

European Coatings Conference “Automotive Coatings”, Berlin November 24th 2011, Dr. Michael Berkei

NANOBYK Additives

Nanotechnology basics


Decreasing electronegativity / Increasing Basicity

Decreasing number

of valent electrons

Size depending

properties

Decreasing electronegativity / Increasing Basicity

Decreasing number

of valent electrons

Size depending

properties

Nanotechnology enables us to obtain more functionalities from chemical elements

Crystal Size [nm]

3 5 10 15 20 30 >100

Gold

Crystal Size [nm]

3 5 10 15 20 30 >100

Gold

Benefits of nanotechnology

Particle size depending change

in colour


Definition of nanotechnology

En

erg

ie

• Change in properties due to a change in size (below 100 nm)

• Conductivity of metals 2 nm

• Fluorescence of Q-dots 10 nm

• Transparency of ceramics 20 nm

• Colour of metals 50 nm

• Stiffness of metals 250 nm

• Ductility of ceramics 500 nm

0%

20%

40%

60%

80%

100%

0 1 2 3 4 5 6 7 8 9 10

Diameter [nm]

Su

rface A

tom

s [

%]

• Increase in specific surface area

• Reactivity

• Surface energy

• Shape

• Anisotropy of properties


Potential Applications

• Improvement in scratch and wear resistance

• Permanent UV protection

• Enhanced anti-microbial activity

• Self-cleaning surfaces

• Conductivity

• Fade-resistant dyes

Nano-Advantage

• Small functional particles

• Maintain transparency

• Low Additive concentration needed

Nanotechnology in Coatings and Plastics


Volume fragment with 1000 µm3 and 2 % particles

particle diameter particle quantity interparticle distance

1 µm 40 2300 nm

20 nm 5,000,000 45 nm

Nanotechnology makes it possible to use

more particles per unit area and to

minimize the particle-particle separation

10 µm

10 µm

10 µm

Advantages of nanoparticles versus microparticles Better distribution at the same concentration level


NANOBYK

Increased coating elasticity

by incorporation of nanoparticles


How nano-based additives improve scratch resistance

SiO2

Curing process

Impact of nanoparticles on elasticity

Polarity differences between nanoparticle and resin

• These differences cause a gradient in crosslinking density

• Around the particle the crosslinking density is lowered

The coating acts like foam and bounces back after exposure

Oligomeric resin

Resin matrix



Source: Lee et al., Macromolecules 2007, 40, 7755-7757

Surface-treated nanoparticles can create „free

volume“ inside a polymeric film resulting in

increased elasticity


Force


Force


Force

Enhanced elasticity

Resin matrix Resin matrix Resin matrix


Mechanism of scratch resistance - nanoindentation


Mechanisms of improved scratch resistance NANOBYK-3652 – 20nm surface treated SiO2

0 % 0.75 % 1.75 % 3 %

Scratch Profiles at 49 mN Test system: Solvent based 2K-PU Coating


Nanoadditives for solvent-born clear coatings

II III

Without nano With 2% SiO2


NANOBYK-3610 and NANOBYK-3650 family Lower E-modulus measured by nanoindentation Test system: Solvent based 2K-PU Coating

0

0,5

1

1,5

2

2,5

3

3,5

4

E-M

od

ulu

s [

GP

a]

0 2 4 6 8

% Additive as supplied on total weight formulation

NANOBYK-3651


NANOBYK-3650, NANOBYK-3651 and NANOBYK-3652: High level of pendulum hardness (König, DIN ISO 1522)

Test system: 2K-PU Clear Coat

80

Dosage:

NANOBYK-3650: 4%

NANOBYK-3651: 5%

NANOBYK-3652: 4%

as supplied on total formulation

90

100

110

120

130

140

Tim

e [s] Control

NANOBYK-3650

NANOBYK-3651

NANOBYK-3652


Application results: Comparison of different surface treated silica nanoparticles in a solvent based 2K-PU clear coat (OEM)

0

10

20

30

40

50

60

70

80

90

100

Con

trol 0

%0,

2%0,

4%0,

6%0,

8%1,

0%1,

2%1,

4%1,

6%1,

8%2,

0%2,

2%2,

4%2,

6%2,

8%3,

0%3,

2%3,

4%3,

6%3,

8%4,

0%

Particle loading [%]

Glo

ss

re

ten

tio

n [

%]

NANOBYK-3650 NANOBYK-3651 NANOBYK-3652

Unpolar surface modification

Medium polar surface modification

Polar surface modification


Application results Solvent-borne 1K TSA clear coat (OEM)

Scratch Resistance of 1K TSA Clear- 140°C/30 min

tested by 9 micron paper on Dry Abrasion Tester (ASTM-D2486)

30

45

60

75

90

105

0 5 10 20 30 40 50 60 70 80 90 100 125 150 175 200 225 250 275 300 325 350 375 400 425 450 475 500

Number of Scratch Cycles (double)

Glo

ss (

20°)

1K-Control

NB3652

NB3652+BYK331

NB3652+BYK300

Nanobyk 3652 dosage: 2% as supplied on total formulation

w eight

Gloss (20°)

substrate: BYKO chart 2833, 100 micron WFT by w ire-w ound bar applicator


Application results Solvent-borne pigmented coatings – 2K systems

Black Silver White

Macrynal SM 510N 60% 30 30 21,7

CAB 551-0.2 (20%ig in Butylactat) 15 15 10,9

Ceratix 8461 (4,7%) 18,2 18,2 13,2

Special Black 4 Paste (25%) 6

Aluminium Slurry Metallux 2152 (50%) 6

Tronox CR-826 Paste (63%) 31,8

BYK 320 0,2 0,2 0,2

BYK 358 0,5 0,5 0,4

Butylacetate 15 15 10,9

Methoxypropylacetate 2,5 2,5 1,8

Shellsol A 2,5 2,5 1,8

n-Butanol 2 2 1,5

Xylene 8 8 5,8

BYK 410 0,1 0,1 0,1

Polyol : Desmodur N75 BA = 5:1


Application Results 2K-Coating Metallic

17%

77%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

Glo

ss R

ete

nti

on

[%

] Control

1% Nanobyk 3650

2% Nanobyk 3650

5% Nanobyk 3650

1% Nanobyk 3651

2% Nanobyk 3651

5% Nanobyk 3651

1% Nanobyk 3652

2% Nanobyk 3652

5% Nanobyk 3652

Dosage level of additives: As supplied on TFW (total formulation weight)

10 Cycles Crockmeter Test 9 MIC polishing paper

NANOBYK

3650 NANOBYK

3651 NANOBYK

3652


Scratch resistance improvement 2K- Coating Metallic

Control with NANOBYK-3652

10 Cycles

Crockmeter Test

9 MIC polishing

paper


Application results 2K- Coating Black

27%

80%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

Glo

ss R

ete

nti

on

[%

]

Control

1% Nanobyk 3650

2% Nanobyk 3650

5% Nanobyk 3650

1% Nanobyk 3651

2% Nanobyk 3651

5% Nanobyk 3651

1% Nanobyk 3652

2% Nanobyk 3652

5% Nanobyk 3652


10 Cycles Crockmeter Test 9 MIC polishing paper

NANOBYK

3650 NANOBYK

3651 NANOBYK

3652


Application results 2K- Coating White

25%

85%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

Glo

ss R

ete

nti

on

[%

]

Control

1% Nanobyk 3650

2% Nanobyk 3650

5% Nanobyk 3650

1% Nanobyk 3651

2% Nanobyk 3651

5% Nanobyk 3651

1% Nanobyk 3652

2% Nanobyk 3652

5% Nanobyk 3652

Crockmeter


NANOBYK

3650 NANOBYK

3651 NANOBYK

3652


NANOBYK-3610 and NANOBYK-3650 family Hardness combined with elasticity

1) Coatings with these additives show lower E-Modulus but hardness

similar to controls

NANOBYK-3610 and NANOBYK-3650 family of products provide higher coating elasticity without affecting hardness

2) They improve scratch resistance by immediate reflow without creating brittleness or downgrading other coating properties

The coating remains almost unharmed


NANOBYK‘s

Increased coating hardness

by incorporation of nanoparticles


SiO2

Acrylic functionality

Oligomeric resin

Oligomeric resin


Impact of nanoparticles on crosslinking density

Curing process

Curing process

Regular crosslinking density

Increased crosslinking density


Application results – scratch resistance (15µm polishing paper Crockmeter test)

0

10

20

30

40

50

60

70

80

90

100

Glo

ss

re

ten

tio

n [

%]

Control 1% NB-3605 2% NB-3605 3% NB-3605 5% NB-3605

Gloss retention [%]

Test procedure: Applied force: 9N; polishing paper 15µm; 10 double roubs



Application results – abrasion resistance (Taber test)

0

2

4

6

8

10

12

NANOBYK-3605

Control 2% NANOBYK-3605 10% NANOBYK-3605 20% NANOBYK-3605

Loss of weight in mg

System: Urethane acrylate (100%) Test procedure: Applied load: 500 g per wheel; 1000 revolutions; CS 10 wheels


Application results – abrasion resistance (Scotch BriteTM test)

D % haze (difference between scratched and non-scratched sample)

System: Polyester Acrylate (100%)

0

10

20

30

40

50

NANOBYK-3605

Control 2% NANOBYK-3605 10% NANOBYK-3605 20% NANOBYK-3605

Test procedure: Hammer with Scotch-BriteTM pad; applied load: 1,1 kg; 10 cycles


Application results – abrasion resistance (Scotch BriteTM test)

20% NANOBYK-3605 Control

After Scotch BriteTM test (5x magnification)

Test procedure: Hammer with Scotch-BriteTM pad; applied load: 1,1 kg; 10 cycles


Application results – stain resistance

Control 20 % NANOBYK-3605

Stamping

ink

Mustard

Test results (according to DIN 68861)

Control 20% NANOBYK-

3605

Vinegar 1 0

Mustard 2 1

Ketchup 0 0

Coffee 1 0

Stamping

ink 4 2

0 = no residues, 5 = strong residues

System: Urethane Acrylate, solvent-borne


NANOBYK-3605

Benefits

• Reactive diluents are used to adjust the viscosity and reactivity of UV-curable systems.

• It is possible to formulate 100% UV- curable systems.

• Additional acrylic surface modification enables an increased crosslink density in the radical polymerization process with the unsaturated acrylic resin.

• Increase of coatings hardness depending on silica concentration.


Life cycle analysis of nano-coatings VdL (German Paint Association)

What happens to nanoparticle containing

coatings, once they become damaged?


In 2007 the VdL (German Paint Association) started a three-fold study on the life cycle of nanoparticle containing coatings.

This study was supported by BYK, Bayer, BASF, PPG, Akzo Nobel, Wacker, and many more companies.

The question was:

What happens to nanoparticle containing coatings, once they become damaged?

The study is divided into three parts:

1) Abrasion

2) Scratching

3) UV-weathering




First results are already published and were presented to the German government


Conclusion

• Surface treated nanoparticles can increase the elasticity of coatings

• Surface treated nanoparticles can crosslink into a polymeric matrix

AND

• The incorporation of nanoparticles into coatings does not increase the number of airborne particles when the coating is abraded.


Thank you very much for your kind attention


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