1. Practical Applications of Polysiloxane Coatings Gerald L
Practical Applications of Polysiloxane Coatings Gerald L. Witucki August 2013
AV11434, AV12869, AV13359, AV06629
We are here to discuss the product launch of Dow Corning® 3055 Resin. This is a liquid, amine-functional siloxane resin with potential utility across coatings markets and beyond. The initial target market is protective topcoats for industrial maintenance applications.

2. Agenda
Evolution of protective coatings and need for amine-functional siloxanes
Features and benefits
Performance testing
Market information
AV13147
This presentation will cover the market/technology needs that drove the development of Dow Corning® 3055 Resin. We will also review application test data and highlight some of the potential market applications for this novel product.

3. Evolution of Protective Coatings
Coatings protect substrates from environmental degradation
Prior to 1990s, typically based on organic binders (e.g., epoxy or polyurethane)
Interest in siloxane technologies is expanding; anticipated (U.S.) AGR: 12%*
Binders Used in Coatings
U.S. Patents Issued for
Polysiloxane-Epoxy Hybrid Coatings Per Year
Silicones 1.4%
As the coatings industry has become globalized, end-customers have demanded optimized and interchangeable systems from their suppliers. Formulators now seek tools to gain differentiation. With the rising cost of labor and oil-based resins, the drive for VOC reduction, and the demand for long- term durability, interest in polysiloxane resin systems has dramatically increased over the last decade, with demand expected to grow 12 percent annually.
*KNG Industry Report

4. ‘Polysiloxane’ Coatings Technology
Broadly, polysiloxane = silicone
In the coatings industry, polysiloxane refers to silicone-organic resin hybrids
Best known are silicone-epoxy and silicone-acrylate systems
Viewed as premium topcoats
Over the last two decades, “polysiloxane” technology has facilitated a shift from three-coat to two-coat systems, reducing labor costs and downtime while improving weathering performance
AV19503
The best-known of the polysiloxane hybrid coatings are the silicone-epoxy and silicone-acrylate systems.

5. Two Coats vs. Three Coats
Urethane Topcoat
3-5 mils
Polysiloxane Hybrid
Epoxy Basecoat
5 mils
5 mils
Zinc Primer
Zinc Primer
Steel

6. ‘Polysiloxane’ Coatings Technology: State-of-the-Art
Includes organic resin, methoxy-functional silicone resin and an amino-functional silane
The silane acts as a bridge between the two resins; the amine group reacts with the functional group on the organic, and the alkoxy groups co-hydrolyze and condense with the silicone
AV17007
These are formulated with an organic resin (e.g., epoxy or acrylate), a methoxy-functional silicone resin (e.g., Dow Corning® 3074 Intermediate) and an amino silane (e.g., XIAMETER® OFS 6011 Silane).
The silane serves as a bridge between the organic and the silicone resins. The amine group reacts with the functionality of the organic resin, and the silane’s alkoxy groups hydrolyze and co-condense with those of the silicone resin.

7. Cure Mechanism of Silane- Based Polysiloxane Coatings
As mentioned earlier, traditional polysiloxane coatings are formulated with an organic resin (e.g., epoxy or acrylate), a methoxy-functional silicone resin (e.g., Dow Corning® 3074 Intermediate) and an amino silane (e.g., XIAMETER® OFS 6011 Silane).
The silane serves as a bridge between the organic and the silicone resins. The amine group reacts with the functionality of the organic resin, and the silane’s alkoxy groups hydrolyze and co-condense with those of the silicone resin.
This chemistry requires the addition of titanate (hydrolysis) and tin (condensation) catalysts along with the presence of ambient moisture. Alcohol is generated, which volatilizes as a VOC and results in mass loss (film shrinkage) and potential stress cracking. In addition, residual alkoxy groups continue to cure over long periods and can lead to embrittlement.
Ameron 1981 Patent: US A

8. Limitations of Silane-Based Polysiloxanes
Feature
Limitation
Rely on moisture for hydrolysis and temperature for condensation
Proper cure is dependent on application conditions
Alkoxy reaction leads to reduced coating mass on the substrate
Causes film stress (cracking and adhesion loss)
Residual alkoxy groups can continue to react after the coating appears fully cured (post-cure drift)
Can result in film embrittlement
Alcohol is an undesirable by-product of alkoxy-functional intermediates
This contributes to VOC of the formulation;
methanol can create labeling issues due to toxicity
The organic reaction occurs within hours of mixing. The inorganic silicone reaction begins immediately upon exposure to moisture, but it is quite dependent upon ambient conditions (temperature and humidity) and can be prolonged for months. As the polysiloxane cures, methanol is generated and volatilizes. The resulting mass loss can result in film stress cracking and adhesion loss. Over the course of months, post-cure drift can result in film embrittlement.
For polysiloxane technology to proliferate in the market, this must move beyond alkoxy cure

9. Beyond Alkoxy Silane Cure
Siloxanes are polymerized silanes
Polymer structure achieved prior to application
Not reliant on ambient conditions to achieve cure
No generation of alcohol during film cure
Compatibility of the siloxane with organics and the level of crosslinking can be “dialed-in” to achieve specific performance requirements
The use of silanes in a paint formulation requires the hydrolysis and condensation of the monomeric silanes post-application. This requires a lot of chemistry to occur under conditions that are not always ideal. Silicones have already completed most of the reactions to form the polymeric structure – so less time and energy is needed. The composition of the silicone can be modified to impart specific properties (e.g., hardness, flexibility, etc.)

10. Utility of Organofunctional Groups in Resin Chemistries
Resin Systems
Carbinol
Phenol
Aldehyde
Amino
Isocyanate
Epoxy
Carboxy
Acrylate
Urethane n
Polyester
Alkyd
Amine
Acrylic
To encourage further growth of the polysiloxane hybrid technology, Dow Corning recognized the need to provide novel materials. Examining the cure chemistries utilized in the coating industry, we noted that carbinol and amine functionalities are used across the six key resin systems.
While both carbinol and amine-functional siloxanes have the potential for broad utility – and Dow Corning has the potential capability of supplying either – the manufacturing process to produce amine-functional siloxanes is more feasible.
Dow Corning has chosen amine functionality to offer a broad utility in coatings resin chemistries

11. Cure Chemistry of Silicone Amine Resin
No tin or titanate catalysts
No reliance on ambient moisture
No alcohol by-product
In comparison, a coating formulated with Dow Corning® 3055 Resin does not require the presence of a titanate or tin catalyst or moisture for curing to happen. No leaving groups volatilize, and there is no residual alkoxy post-cure drift.

12. Silicone Amine Resin Typical Properties
Viscosity at 25ºC (77ºF): 2,500-5,000 cSt
Amine equivalent weight: grams/NH
Nonvolatile effective content: >97%*
Appearance: clear and water-white to light straw
*When reacted with organic resin
Dow Corning® 3055 Resin represents the first commercial offering of what is anticipated to be a family of organofunctional products.
Dow Corning® 3055 Resin is a high-solids, liquid, amine-functional silicone resin designed to reduce the potential embrittlement of polysiloxane hybrids.

13. Differentiated Performance of Silicone Amine Resin
Feature
Benefit
<1% residual solvent, amine-functional silicone resin
Formulate to lower VOC regulations
Offers improved chemical, weathering, thermal and corrosion resistance over traditional epoxy coatings
Higher level of coating performance and durability
Comparable physical properties to two-component polyurethane, but with better corrosion resistance
Potential to replace the three-coat system with a two-coat system for labor cost and downtime reduction
Potential utility in other coatings applications and new markets
Can use anywhere that amine functionality is utilized
We have compared the performance of Dow Corning® 3055 Resin against that of traditional epoxies and polyurethane topcoats. It offers improved chemical, weathering, thermal and corrosion resistance over traditional epoxy coatings and comparable physical properties to 2K PU, but with better corrosion resistance. This gives potential to replace the three-coat system with a two-coat system for labor cost and downtime reduction.

14. Benefits of Silicone Amine Resin
Competitive
Amino Si Resin
Alkoxy Silane-Based Polysiloxane
Two-Component Polyurethane
Solvent content
<1%
10%
25%*
Post-cure drift potential
Low
High
None
HAPS content No
Yes (xylene)
Isocyanate hazard
Yes
Methanol hazard
Application coats
Primer/top
Primer/base/top
Whereas the Dow Corning® 3055 Resin is delivered with less than 1 percent of residual solvent, the competitive resin is supplied as a resin solution in xylene. Many formulators view the presence of this hazardous air pollutant as a fatal flaw.
The traditional polysiloxane utilizes solventless resins, such as Dow Corning® 3074 Intermediate, that possess approximately 15 weight percent methoxy functionality. Upon application, the methoxy groups hydrolyze to generate methanol, which is both a VOC and a potential health hazard.
2K polyurethanes are less conducive to formulating ultra-high-solids coatings. Often, these resins are supplied at approximately 75% solids. Also, the isocyanate functionality poses a health concern.
In an industrial maintenance coating application, polyurethanes are often applied as the weatherable topcoat over an epoxy basecoat and zinc-rich primer that provide the essential corrosion protection. With a zinc-rich primer and polysiloxane hybrid topcoat, the coating process is reduced to two coats, saving labor and downtime expenses.
*As supplied

15. Performance Testing
Cycloaliphatic epoxy resin crosslinked with silicone amine resin
Pigmented with TiO2 (0.8 pigment: binder)
Compared against:
Silane-based polysiloxane
Organic polyamine crosslinker
Polyurethane acrylic
Also evaluated additions of alkoxy-functional siloxane and hindered amine light stabilizer
A lab study compared the performance of a silicone-epoxy polysiloxane hybrid topcoat formulation against an organic polyamine-cured epoxy, 2K polyurethane, and a silane-crosslinked polysiloxane. The additions of a hindered amine light stabilizer (HALS) and an alkoxy-functional silicone resin were also examined.

16. Circular Dry Time
Circular Dry Time, hr
Set to Touch
Surface Dry
Through
Dry
Silicone amine resin/organic amine (15% Si) 4 6
7.5
Silicone amine resin/organic amine (30% Si)
2.5
4.25 8
Silicone amine resin (56% Si) 3 5 7
Organic amine (0% Si)
3.5
Amino silane (23% Si) 1 16
Silicone amine resin/silane (44% Si)
6.5
Alkoxy silicone/silane (56% Si)
Silicone amine resin/alkoxy silicone (70% Si) 2
5.5
2K PU (0% Si)
9.5 14
The rate of cure of each system was evaluated by making 6 mil drawdowns on glass panels and testing via a Gardner Circular Drying Time apparatus. Epoxy- based coatings provide overall faster dry times versus PU chemistry. Dow Corning® 3055 Resin’s cure is comparable to organic crosslinker. The alkoxy silane-based polysiloxane cured fastest (at ambient lab conditions).
Epoxy-based coatings provide overall faster dry times versus polyurethane chemistry
Silicone amine resin cure is comparable to organic crosslinker
The alkoxy silane-based polysiloxane cured fastest (at ambient lab conditions)

17. MEK Resistance, dbl rubs Mandrel Flexibility, inches
Film Properties
Pendulum Hardness
MEK
Resistance, dbl rubs
Mandrel
Flexibility, inches
Silicone amine resin/organic amine (15% Si)
114
>300
1/4
Silicone amine resin/organic amine (30% Si)
106
250
Silicone amine resin (56% Si) 85
135
3/16
Organic amine (0% Si)
103
Amino silane (23% Si) 28
125
Silicone amine resin/silane (44% Si) 64 80
Alkoxy silicone/silane (56% Si) 94
155
5/16
Silicone amine resin/alkoxy silicone (70% Si) 78 37
PU (0% Si)
129
<1/8
Pendulum Hardness
MEK Resistance, dbl rubs
Mandrel Flexibility, inches
Silicone amine resin/organic amine (15% Si)
114
>300
1/4
Silicone amine resin/organic amine (30% Si)
106
250
Silicone amine resin (56% Si) 85
135
3/16
Organic amine (0% Si)
103
Amino silane (23% Si) 28
125
Silicone amine resin/silane (44% Si) 64 80
Alkoxy silicone/silane (56% Si) 94
155
5/16
Silicone amine resin/alkoxy silicone (70% Si) 78 37
PU (0% Si)
129
<1/8
AV19502
Six mil drawdowns were made onto aluminum panels and allowed to air-dry for 10 days before evaluation. All formed hard (>H) films with good solvent (MEK) resistance.
The paints were all comparable in terms of gloss, but the three epoxy-containing formulations (1,2,3) outperformed the polyurethane (4) in terms of distinctness of image. The hardness of polyurethane was higher than the epoxies, but that was to be expected. Due to the concern of embrittlement, we formulated the epoxies (1,2,3) to be soft.
The paints were all comparable in terms of gloss, but the epoxy-containing formulations outperformed the polyurethane in terms of distinctness of image (DOI)

18. Epoxy + Silicone Amine Resin
Chemical Resistance #
Chemical 1
Acetic acid (10%) 2
Formic acid (10%) 3
Hydrochloric acid (36%) 4
Nitric acid (50%) 5
Phosphoric acid (50%) 6
Sulfuric acid (50%) 7
Ammonium hydroxide (20%) 8
Potassium hydroxide (20%) 9
Sodium hydroxide (20%)
Epoxy + Silicone Amine Resin
Epoxy + Organic Amine
Chemical resistance testing of a cycloaliphatic epoxy topcoat crosslinked with Dow Corning® 3055 Resin or an organic polyamine demonstrates true synergy. While siloxanes alone do not possess the level of chemical resistance attributed to epoxy coatings, the polysiloxane hybrid (panel on left) exhibits chemical resistance superior to that of the organic control.
We assessed chemical resistance of a cycloaliphatic epoxy resin crosslinked with Dow Corning® 3055 Resin against a coating based on a polyamine, a traditional polysiloxane-epoxy and a 2K polyurethane. The results show that Dow Corning® 3055 Resin provides chemical resistance greater than the organic polyamine and comparable to the traditional siloxane. The polyurethane exhibited the best chemical resistance.
Five drops of chemical; covered with watch glass for 24 hours
Adding silicone amine resin improves the chemical resistance beyond that of a traditional epoxy coating

19. UV Durability 20° Gloss AFTER QUV-A Exposure
Silicone amine resin outperforms state-of-the-art polysiloxane
Increasing the percentage of silicone provides performance comparable to PU

20. Outdoor Weather Resistance
20° Gloss AFTER OUTDOOR MICHIGAN EXPOSURE
Upon outdoor exposure, the organic control quickly exhibited yellowing. The Dow Corning® 3055 Resin sample was comparable to that of the traditional polysiloxane. The addition of 1% of a hindered amine light stabilizer (BASF Tinuvin® 123) resulted in performance comparable to the polyurethane.
Silicone amine resin yellowing:
comparable to state-of-the-art polysiloxane

21. Flexibility After Weathering
Mandrel Bend Rating, inches
%Si
After 10 Days
One Year Outdoors
Alkoxy silane-based polysiloxane 50
>1 5
Epoxy + silicone amine resin 1
4-inch mandrel bend – silane-based polysiloxane
After one year of outdoor exposure, silicone amine resin paint retains flexibility
Comparing flexibility of the silane-crosslinked polysiloxane against that of Dow Corning® 3055 Resin, we see comparable initial results, but after one year of exterior exposure, the silane-crosslinked coating has become less flexible, while the Dow Corning® 3055 Resin formulation maintains flexibility.
THIS IS THE FIRST OF TWO CRITICAL POINTS TO DRIVE HOME. THIS PERFORMANCE IS CENTRAL TO THE ARGUMENT THAT DOW CORNING® 3055 RESIN CAN BE USED TO FORMULATE POLYSILOXANE HYBRID COATINGS THAT DO NOT SUFFER THE POST-CURE EMBRITTLEMENT OF ALKOXY SILANE-BASED SYSTEMS.
The elimination of alkoxy functionality and total reliance on amine functionality to crosslink the silicone polymer eliminates the post-cure drift.
1-inch mandrel bend – with silicone amine resin

22. Water absorption decreases with higher use of silicone amine resin
CYCLOALIPHATIC EPOXY (%WT GAIN)
Water absorption decreases with higher use of silicone amine resin
BPA EPOXY RESIN (%WT GAIN)
Samples of each BPA epoxy resin system were cast as 4 gram tablets (triplicate), allowed to cure for 10 days, weighed and then placed into deionized water. Every 10 days, the samples were removed from the water, surface-dried and reweighed.
Water absorption decreases as the level of Dow Corning® 3055 Resin increases.

23. Thermal Stability Performance
THERMAL STABILITY WITH A CYCLOALIPHATIC EPOXY
Thermogravimetric analysis (TGA) measures weight loss at time and temperature
THERMAL STABILITY WITH A BPA EPOXY
As would be expected with the inclusion of a siloxane resin, Dow Corning® 3055 Resin improves the thermal stability of the cycloaliphatic epoxy. Not only is the onset of thermal degradation delayed (from approximately 150°C to 250°C), after 600°C, the epoxy is totally vaporized, while the silicone retains a portion of its mass.
Silicone amine resin reduces thermal degradation

24. Increased Si content improves corrosion resistance
Cycloaliphatic epoxy paint
Spray-applied
Ground cold-rolled steel panels
1,500 hours salt spray (scribed)
Scribe Creep, mm
Silicone amine resin/organic amine (50% Si) 55
Silicone amine resin/alkoxy silicone (60% Si) 48
Silicone amine resin/alkoxy silicone (70% Si) 37
Epoxy (with organic amine) 57
Two-component polyurethane 67
As mentioned earlier, a benefit of polysiloxane technology in comparison with polyurethane topcoats is the ability to reduce the coating process from three steps (primer/base/top) down to two (primer/top). Though polyurethanes have good weather and chemical resistance, they lack corrosion resistance. Thus polyurethanes need the epoxy basecoat.
THIS IS THE SECOND CRITICAL POINT TO DRIVE HOME. THIS PERFORMANCE IS CENTRAL TO THE ARGUMENT THAT TWO-COAT POLYSILOXANE TOPCOATS CAN BE USED TO REPLACE THE THREE-COAT POLYURETHANE COATING SYSTEMS.
Salt-spray corrosion test results show that the Dow Corning® 3055 Resin-crosslinked cycloaliphatic epoxy performs as well as the epoxy control. The polyurethane, on the other hand, exhibited scribe creep (cathodic disbondment) across nearly the width of the test panel.
Increased Si content improves corrosion resistance

25. Solvent Solubility of Silicone Amine Resin
Checked at 10, 50 and 90% NVC in various solvents
Acceptable: alcohols and aromatics
Ester alcohol, methanol, butanol, 2-propanol, EEP, PCBTF, xylene, toluene
Unacceptable: aliphatics, acetates
Ethylene glycol, ethylene glycol butyl ether (color), heptane, mineral spirit (OK as diluent), Aromatic 150 (color)
Ketones are good solvents for silicone resins, but they react with amines to form ketimines, which will not react with epoxies until hydrolyzed

26. White Gloss Topcoat – Ingredients
Example Formulations
White Gloss Topcoat – Ingredients
% Silicone 50 60 70
Cycloaliphatic epoxy resin
25.68
22.03
16.50
Silicone amine resin (5% xs NH)
27.58
28.86
21.62
Organic polyamine
1.75
Alkoxy silicone resin
4.09
16.82
Rutile TiO2
44.01
43.99
43.95
Dibutyltin dilaurate
0.01
0.03
Tetrabutyltitanate
0.02
0.08
Hindered amine light stabilizer
0.97
0.99
Xylene as needed
100
These formulations are offered as starting points for basic silicone-epoxy topcoat finishes. The performance demands of specific applications require optimization.
Silicone amine resin may be blended with other Si resins or organic resins to customize performance

27. Other Formulating Options
Performance can be boosted with the inclusion of additional siloxane resins (above that dictated by amine stoichiometry)
Acrylates can reduce dry-to-touch time by reacting quickly with the amines via Michael addition
The addition of ketones such as methylisobutylketone (MIBK) to silicone amine resin can extend pot life by reacting with the amine groups to form ketimines
Reaction time is dependent upon amine-epoxy concentration, so increasing the functionality will speed cure
Tertiary amines and polyols are known to accelerate the amine-epoxy reaction
Compatible with low-viscosity novolac resins
Here are a few formulation options that provide latitude to meet specific application demands. THE SLIDE IS SELF EXPLANATORY.

28. Conclusions
Amine functionality provides potential utility in a broad range of chemistries
Allows for low-VOC formulating
Cure chemistry eliminates mass loss, stress cracking and post-cure drift
Silicone amine resin improves epoxy coatings’ resistance to chemical, thermal, UV and moisture attack
Comparable physical properties to two-component polyurethane, but with better corrosion resistance
Allows for replacing three-coat system with two-coat (primer/topcoat) system for labor cost and downtime reduction
Dow Corning® 3055 Resin offers formulators a novel means by which to formulate high-performance coatings.
Dow Corning has gained global patents on the composition and several applications for Dow Corning® 3055 Resin. Our intent is to offer this as a global product. Global registration is in place with the exception of Japan, Australia, New Zealand and Canada. Research sampling is allowed everywhere except Australia and New Zealand. Commercial launch is scheduled for Q

29. Amino Resin Coatings Applications*
Industrial/protective coatings
Water/wastewater facilities
Metal containers
Coil
Wood furniture
Metal furniture
Prefinished wood
Appliances
Machinery & equipment
Electrical insulation
Automotive
Land transportation
General metal & misc. OEM
Potential utility may be found where improved properties of flexibility, weathering, corrosion, water and heat resistance are needed
AV10606, AV18647, AV16985
Though the initial application targeted for Dow Corning® 3055 Resin is industrial protective maintenance coatings, there are other high-value applications that currently utilize amine-functional polymers. Many of these could benefit from the improved thermal, weather and chemical resistance provided by Dow Corning® 3055 Resin.
*KNG Industry Report

30. Potential Beyond Traditional Protective Coatings
Amine functionality offers potential opportunities in a wide range of applications and chemistries:
Fire-resistant and intumescent coatings
Composite polymers
Industrial adhesives
High-temperature coatings
AV16377, AV18509, AV19501
The broad utility of amine chemistry and the well-known benefits of siloxane polymers provide Dow Corning® 3055 Resin with potential utility beyond coatings.
Anywhere amine polymers are used

31. Learn More About Dow Corning® 3055 Resin
Visit dowcorning.com/coatings for technical data sheets, informational brochures and more information on Dow Corning® brand products
Look for our 10-part series on YouTube; Search for “3055 Resin” and learn how Dow Corning® 3055 Resin can help you formulate durable protective coatings

32. For More Information
For more information or to order samples, contact your local Univar representative, or:
Visit univarusa.com
Call

33. Q & A

34. The formulations described on slide 26 represent potential use of Dow Corning material and are not commercialized products. Dow Corning believes that the information and data on which these formulations are based are reliable, but have not been subjected to extensive testing for performance, efficacy or safety. In addition, Dow Corning has not undertaken a comprehensive patent search on the formulations. Suggestions of uses should not be taken as inducements to infringe any particular patent.
BEFORE COMMERCIALIZATION, YOU SHOULD THOROUGHLY TEST THE FORMULATION OR ANY VARIATION OF IT TO DETERMINE ITS PERFORMANCE, EFFICACY AND SAFETY. IT IS YOUR RESPONSIBILITY TO OBTAIN ANY NECESSARY GOVERNMENT CLEARANCE, LICENSE OR REGISTRATION.