Hydrolytically Stable Silane

1

Novel

Hydrolytically

Stable Silane

Additives for

Improving the

Performance of

Waterborne Acrylic

Roof Coatings

Jacob Shevrin

Applied Technology Manager

Evonik Corporation

2021

2

The Importance & Requirements of Cool Roofing

Reduce ambient and indoor air temperatures

Climate change mitigation

Reduce heat island effect

Energy savings

Long-term trend toward reflective roofing

Requirements

ASTM D6083 I & II

Water resistance

Solar reflectance

Stain resistance

Elongation and toughness

Evonik Corporation | CTT 2021 | Novel Hydrolytically Stable Silane Additives for Improving the Performance of Waterborne Acrylic Roof Coatings

3 Evonik Corporation | CTT 2021 | Novel Hydrolytically Stable Silane Additives for Improving the Performance of Waterborne Acrylic Roof Coatings

Effects of Silanes in Roof Coatings Ponding water resistance

Reduce water uptake by 40-70%

Improve wet adhesion up to 40-150+%

Primerless dry adhesion

Up to 40% improvement on difficult substrates

Improved stain resistance

Weatherability & durability

4

Why hasn’t this been done before?

Stability.

5

Hydrolyzable alkoxy groups on silanes are water

reactive

Traditional silanes are shelf-stable in aqueous

dispersion for only days/weeks

Unstable silanes cause viscosity increase and gelling

Increasing hydrolytic stability of alkoxy group increases

shelf stability

methoxy < ethoxy < dialkoxy < oligomeric

Silanes must be reactive enough to improve the final

coating

Increasing hydrolytic stability

Stability of Silanes in Aqueous Dispersions

Organofunctional group

Hydrolyzable

alkoxy groups

Silane Structure


6

Comprehensive Study of Silanes in Waterborne Acrylic Roof Coatings

Elastomeric roof coatings formulas based on

• Waterborne Acrylic Resin

Two silanes ultimately selected for their stability in water

• Amine-functional silane monomer

• Epoxy-functional silane oligomer

Performance testing

• Stability (viscosity v. time at 45C)

• Water resistance (ASTM D471, 7 day immersion)

• Dry & wet adhesion (ASTM C794, 7 day immersion)

• Stain resistance (ASTM D3719, carbon black, iron oxide slurry)

• Physical properties, initial and aged (ASTM D2370, 1000h QUV)

Substrates (aged):

• PVC*, EPDM*, Asphalt^

* Weathered in QUV for 350 hours^Weathered outdoors for 3 months

Stability Adhesion

Water Resistance

Elongation

Stain Resistance


7

Meet the Candidates

Epoxy-functional Silane Oligomer

• Oligomeric, low-monomer epoxy silane

• Colorless and non-yellowing

• 258 – 320 g/L VOC (methanol)

• No hazard label

• TSCA listed

Amine-functional Silane Monomer

Monomeric, amine functional

Dialkoxysilane

Colorless to yellow

443 g/L VOC (ethanol)

Corrosive hazard label

TSCA listed

Properties

Molecular weight g/mol > 2000

Viscosity (25 °C) mPa∙s 700 - 1200

Flash point °C > 93

Amine-functional Silane Monomer Properties

Molecular weight g/mol 191

Viscosity (25 °C) mPa∙s 2

Flash point °C 88


Epoxy-functional Silane Oligomer

R = X = glycidoxypropyl

8

Waterborne Acrylic Roof Coating Formulation

Material SupplierQuantity

(wt%)

Grind

DI H2O - 12.51

Dispersant BASF 0.40

Dispersant ICL Phosphate Specialty 0.12

Calcium Carbonate Huber Engineered Materials 34.95

Titanium Dioxide Chemours 5.83

Zinc Oxide Sigma Aldrich 3.88

Letdown (after 24h sitting)

Waterborne Acrylic

ResinDOW 38.95

Coalescent Eastman 0.58

Biocide DOW 0.17

Aqueous Ammonia Sigma Aldrich 0.08

Propylene Glycol Sigma Aldrich 2.02

Thickener Ashland 0.35

Total 100.00

Procedure

1. Add DI Water to container under low speed

2. Add dispersants to container under low speed

3. Under low speed, add Calcium Carbonate, Titanium Dioxide,

and Zinc Oxide to container

4. Mix at high speed in dispermat for 15 – 30 minutes

5. Return to low mixing speed

6. Add Waterborne Acrylic Resin under low speed

7. Add coalescent under low speed

8. Add biocide under low speed

9. Premix Propylene Glycol and thickener out of container

10. Add Aqueous Ammonia under low speed

11. Immediately add Propylene Glycol + thickener to container

and mix under low speed

12. Post-add 0.22% silane (1% on resin solids)


9

Stability – Silanes in Waterborne Acrylic Resin

• 45C oven, 8 weeks = 12 months at room temp.

• Both silanes relatively stable compared to control

• Unstable silanes (not shown) gelled in 2-4 weeks

0

500

1000

1500

2000

2500

3000

3500

4000

Week 0 Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 8 Week 12

Vis

co

sit

y (

ce

nti

po

ise

)

Control Epoxy-functional Silane Oligomer Amine-functional Silane Monomer

On

e Y

ear


10

Water Resistance - Silanes in Waterborne Acrylic Roof Coating

• ASTM D471 (on aluminum), 7 day immersion

• Epoxy-functional Silane Oligomer reduced water

uptake by >60%

• Epoxy-functional Silane Oligomer prevented

delamination and blistering

• Amine-functional Silane Monomer reduced water

uptake by 40% but still delaminated

• Control gained considerable weight, blistered

Epoxy-functional

Silane Oligomer

+2.8% water

weight gain

Amine-functional

Silane Monomer

+4.4% water

weight gain

Delamination

+7.2% water

weight gain

Control

Blistering


11

Dry and Wet Adhesion to PVC – Silanes in Waterborne Acrylic Roof Coating

0

2

4

6

8

10

12

14

16

18

20

Control Amine-functional SilaneMonomer

Epoxy-functional SilaneOligomer

Epoxy-functional Silane Oligomer increased dry

and wet adhesion to PVC by 40-45%

Amine-functional Silane Monomer did not

increase adhesion to PVC

Dry

Wet

Dry

Wet

Dry

Wet

Ad

he

sio

n (

pli

)

CF CF

CF

CF cohesive failure

AF adhesive failure

MF mixed failure

CFCF

CF


12

Dry and Wet Adhesion to EPDM – Silanes in Waterborne Acrylic Roof Coating

0

1

2

3

4

5

6

7

8

9

10



Epoxy-functional Silane Oligomer improved wet

adhesion to EPDM by >150%

Control lost over 80% of adhesion to EPDM

when exposed to water

Amine-functional Silane Monomer reduced dry

adhesion and had no effect on wet adhesion

Dry

We

t

Dry

Wet

Dry

Wet

Ad

he

sio

n (

pli

)

AF

AF

CF

CF cohesive failure

AF adhesive failure

MF mixed failure

AF AF

MF

Dry Adhesion

Control

Epoxy-

functional

Silane

Oligomer

Wet Adhesion

Epoxy-

functional

Silane

Oligomer


Control

13

0

2

4

6

8

10

12



Dry and Wet Adhesion to Asphalt – Silanes in Waterborne Acrylic Roof Coating

Epoxy-functional Silane Oligomer and Amine-

functional Silane Monomer resulted in cohesion

failure compared to control adhesion failure

Amine-functional Silane Monomer improved dry

and wet adhesion to asphalt by >130%

Dry

Wet

Dry

Wet

Dry

Wet

Ad

he

sio

n (

pli

)

AF

CF

CFCF cohesive failure

AF adhesive failure

MF mixed failure

AF

CF

CF

Dry Adhesion Wet Adhesion


Epoxy-

functional

Silane

Oligomer

Epoxy-

functional

Silane

Oligomer

ControlControl

14

Contact Angle – Silanes in Waterborne Acrylic Roof Coating

1000h QUV

Silanes have minimal effect on surface contact

angle in waterborne acrylic roof coating

64

65

66

67

68

69

70

71

72

73



Co

nta

ct

An

gle

(°)

Initia

l

Aged

Initia

l

Ag

ed

Initia

l

Aged


15

Stain Resistance – Silanes in Waterborne Acrylic Roof Coating

Epoxy-functional Silane Oligomer and Amine-

functional Silane Monomer both resisted

staining more than coating made without silane

ControlAmine-functional

Silane Monomer

Epoxy-functional

Silane Oligomer


Carbon

Black

Red Iron

Oxide

16

Elongation – Silanes in Waterborne Acrylic Roof Coating

1000h QUV

Silane did not affect initial elongation

Coatings with Amine-functional Silane

Monomer & Epoxy-functional Silane Oligomer

retained more elongation after aging

0

20

40

60

80

100

120

140

160



Initia

l

Aged

Initia

l

Aged

Initia

l

Aged

Elo

ng

ati

on

at

bre

ak

, %


17

Tensile Strength – Silanes in Waterborne Acrylic Roof Coating

1000h QUV

Epoxy-functional Silane Oligomer increased

initial & aged tensile strength by 20-30%

Amine-functional Silane Monomer reduced initial

tensile strength that was regained upon aging

0

0.5

1

1.5

2

2.5

3

3.5

4



Initia

l

Aged

Initia

l

Ag

ed

Initia

l

Aged

MP

a


18

Coating Appearance, Aged – Silanes in Waterborne Acrylic Roof Coating

1000h QUV on aluminum panels

All coatings were free of defectsControl Amine-functional

Silane Monomer

Epoxy-functional

Silane Oligomer


19

Silanes for Acrylic Roof Coatings

Resist ponding water

• Reduce water uptake 60-70%

• Increase wet adhesion to EPDM 130-150%

• Increase wet adhesion to PVC 20-45%

• Prevent delamination and blistering

Reduce staining

• Improve removal of carbon black and iron oxide

Increase durability

• Better flexibility and tensile strength

• Improve weather resistance

Shelf stable

Immediately available & TSCA listed


20

Contact Evonik Silanes

Jacob Shevrin

Applied Technology Manager, North America

[email protected]

+1 732-981-5004

Disclaimer

This information and all further technical advice are based on our present knowledge and experience. However, it implies no liability or other legal responsibility on our

part including with regard to existing third party intellectual property right, especially patent rights. In particular, no warranty, whether express or implied, or guarantee of

product properties in the legal sense is intended or implied. We reserve the right to make any changes according to technological progress or further developments.

The customer is not released from the obligation to conduct careful inspection and testing of incoming goods. Performance of the products described herein should be

verified by testing, which should be carried out only by qualified experts in the sole responsibility of a customer. Reference to trade names used by other companies is

neither a recommendation, nor does it imply that similar products could not be used.


21

Hydrolytically Stable Silane

Documents