Next Generation Polyester Dispersion for 2K Waterborne Urethane Coatings

Michael Knight

Polynt Composites USA Inc.

Technical Service Manager

October 26-28, 2015

Agenda

Background Polyester development 2K waterborne polyester dispersion Outgassing Chemical resistance Salt spray resistance Conclusion

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Background

Waterborne 2K urethane coatings since 1980’s As VOC regulations tightened, waterborne 2K

more prevalent– Flooring, kitchen cabinets, golf balls

Advances in water dispersible isocyanates and waterborne polyols

DTM and corrosion has not been addressed Advancements have been made with a polyester

dispersion over B-1000 treated steel

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Polyester Development - Background

Development of BPA-NI can coatings– BPA under scrutiny by FDA and European regulatory

agencies

Biggest hurdle for polyester was retort– Foods sterilized in can with superheated steam under

pressure – 90 minutes at 250 F Mimic epoxy high Tg and formability Highly hydrophobic polyester High Tg High molecular weight Low hydroxyl for minimal crosslinking

2K Waterborne Polyester - Development

Apply same approach, use same basic polyester backbone

Increase hydroxyl number from 30 to 150– Reactivity with isocyanate– Resultant lower Mw

Maintain hydrophobic, cyclic backbone Maintain water resistance Tightly internal crosslink density

– Highly branched

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2K Waterborne Urethane Formulation

Critical parameters– 1.5 eq. NCO/1.0 eq. OH– Type of isocyanate– Side reaction with water

• CO2 outgassing

– Critical physical tests• Hardness development

• Adhesion to CRS and aluminum

• Chemical resistance

• Corrosion resistance– B-1000– 240 hrs. salt spray, scrape scribe

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Outgassing

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Commercial Experimental

Hardness and Adhesion

Tested with three different isocyanates:

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Hardness and Adhesion

Polynt Resin NCO NCO Eq. FB (mils)72 Hrs. Konig

(sec)Crosshatch Adhesion

(CRS / AL)

Commercial Easaqua XL 600a 1.5 1.51 66 4 / 2

Experimental Easaqua XL 600 1.5 1.51 153 5 / 5

 

Commercial Bayhydur XP-2655b 1.5 1.51 56 0 / 0

Experimental Bayhydur XP-2655 1.5 1.54 163 5 / 5

 

Commercial Bayhydur 302 1.5 1.52 39 5 / 5

Experimental Bayhydur 302 1.5 1.54 92 5 / 5aPerstorp, bBayer

Chemical Resistance

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Chemical Resistance

Polynt Resin NCO FantastikFormula

409 BleachBrake Fluid

1:1 Antifreeze

10% HCL

10%NaOH

Commercial Easaqua XL 600 5 1 8 1 7 1 0

Experimental Easaqua XL 600 10 10 10 5 10 10 5

 

Commercial Bayhydur XP-2655 5 1 8 3 7 1 0

Experimental Bayhydur XP-2655 10 5 8 5 10 5 5

 

Commercial Bayhydur 302 1 1 10 5 10 1 0

Experimental Bayhydur 302 8 8 10 5 10 10 5

10 = Best 0 = Worst

Tested with three different isocyanates:

Corrosion Resistance

– Bayhydur 302– Bayhydur XP-2547– Bayhydur XP-2655– Bayhydur XP-2487/1– Bayhydur XP-2655 / 401-70 (75 / 25)– Bayhydur XP-2547 / XP-2655 (75 / 25)– Bayhydur XP-2547 / XP-2655 (50 / 50)– Bayhydur XP-2547 / XP-2655 (25 / 75)

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Isocyanates tested expanded to 11 different isocyanates or blends

– Easaqua XL-600– Easaqua XD-803 (HDI / IPDI blend)– Easaqua XM-501 (most hydrophobic)

Corrosion Resistance

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Salt Spray Results - 240 Hours

Formula # Description Substrate

Field

Scribe Blister Blister Corrosion

517-173H Commercial/Bayhydur 302 B-1000 9vd 10 9vd8m

517-172A Experimental/Bayhydur 302 B-1000 9m-8f 9g 9d8md

517-172B Experimental/Bayhydur XP-2655 B-1000 10 10 9d7vf

Rating Key:Blisters 0-10 with 0 being largest size blister:

F =few blisters

M =medium amount of blisters

MD =medium dense blisters

D =dense blisters

VD =very dense

Creepage (corrosion extending from scribe mark):10 = no

creepage9 = up

to 0.5 mm8 = up

to 1.0 mm7 = up

to 2.0 mm6 = up

to 3.0 mm5 = up

to 5.0 mm4 = up

to 7.0 mm3 = up

to 10.0 mm2 = up

to 13.0 mm1 = up

to 16.0 mm0 =

over 16.0 mm

Corrosion 0-10 with 0 being 100% corrosion:P =

pinpoint corrosionS =

spot corrosionG =

general corrosion

“>” = not quite as bad as the value given, but not as good as the value one higher than the value given“<” = not quite as good as the value given, but not as bad as the value one lower than the value given

Creepage reported as Average, Maximum, and % of creep to the maximum degree

Salt Spray Results – 240 Hours on B-1000 (scribe scraped with spatula)

Corrosion Resistance

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Before Scraping

Commercial with 1.5 Eq. Bayhydur 302

Before Scraping

Experimental with 1.5 Eq. Bayhydur 302

Salt Spray Results – 240 Hours on B-1000 (scribe scraped with spatula)

Corrosion Resistance

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Experimental with 1.5 Eq. Bayhydur XP-2655

Before Scraping

2K Waterborne Formulation

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The experimental polyester dispersion can be formulated to less than 50 g/L without the use of plasticizers or coalescing additives. This high gloss formula provides excellent adhesion to steel.

High Gloss White 2K System with Experimental Polyester Dispersion

Ingredients Function Pounds Gallons

Component A:      

Grind:

Distilled Water Diluent 70.91 8.51

Disperbyk 190a Dispersant 6.05 0.68

BYK-1710a Defoamer 1.28 0.26

Ti-Pure R-902b Pigment 267.06 8.02

Grind with glass beads to a 7 Hegman

Letdown:      

Experimental Polyester Dispersionc Binder 556.94 62.86

BYK-346a Surfactant 2.63 0.31

BYK-3455a Surfactant 1.32 0.15

15% NaNO3 Flash rust inhibitor 2.49 0.29

Component B:      

Bayhydur XP-2655d Binder 141.49 14.65

Distilled Water Diluent 35.57 4.27

Mix components A & B for 10-15 minutes with mechanical mixing

Total Formulation  1085.74 100.00

Formulation Constants   Paint Properties

Nonvolatile by weight (%) 54.0   Gloss - 20° 87.8

Nonvolatile by volume (%) 44.01   Gloss - 20° 93.4

Weight per gallon (lbs/gal) 10.85   Gloss - 20° 11.5

Pigment to binder ratio 0.83   

PVC (%) 21.62   

Calculated VOC (lbs/gal) 0.02   

Calculated VOC (g/L) 2.35   

1.5 eq NCO/1.0 eq OH   

Other Approaches to Improve Salt Spray Results

Modify polyester with hydrophobic, cyclic polyols or anhydrides– Tricyclodecane dimethanol

– Nadic anhydride

– Trimellitic anyhdride– Terephthalic anhydride– Others

• High Tg phenoxy

• Carbonate diols

• Silane coupling agents

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Summary

Two to three times harder Improved adhesion to CRS and AL Improved chemical resistance Improved corrosion resistance on B-1000 Next generation polyester dispersion for 2K

waterborne urethane coatings should be commercial by Q2 2015

Any questions …