Transcript T3A) Specialty Additives for Waterborne Architectural Coatings

Specialty Additives for
Architectural Coatings
PNWSCT Coatings Fest 2014
Rocky Prior, Charlie Hegedus, Ingrid Meier
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Objective
• Provide guidance for selection of
specialty additives for architectural
coatings
• Discuss a variety of different additive
types
• Provide general chemistry descriptions
• Describe unique properties and benefits
• Provide performance examples and
guidelines for additive selection
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Multi-Functional Surfactants
• Improve substrate and pigment wetting. Increase
coating flow and leveling
• Can affect other properties such as adhesion,
foam, rheology, minimum film formation
temperature, etc.




Traditional Surfactants
Low Foam Dynamic Wetting Agents
Superwetting Surfactants
Coalescing Surfactants
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Traditional Surfactants Used in
Architectural Coatings
• Provide surface tension reduction to wet both
pigment and substrate; can improve color
development and color acceptance
• Also can improve other properties such as viscosity
stability, freeze-thaw stability, scrub resistance
• Tend to stabilize foam, requiring defoamer
• Primarily nonionic surfactants that range in HLB
• Originally, alkylphenol ethoxylates (APEs) and
modified APEs dominated
• Non-APE alcohol ethoxylates are replacing APEs
- Comparable or improved performance to APE surfactants
- Can often be “drop in” replacements
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Low Foam Dynamic Wetting Agents
• Gemini structures that contain two amphiphilic
groups linked with a short “spacer”
hydrophile
hydrophobe
• Unique molecular structures do not stabilize foam
and prevent these surfactants from interacting
strongly with other system components
• This feature makes these wetting agents ideal for
use in Architectural Coatings because they can
perform their intended function without adversely
affecting other properties
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Low Foam Dynamic Wetting Agent:
No Adverse Viscosity Effects in Vinyl
Acrylic Wall Paint
105
White semi-gloss wall and trim vinyl
acrylic interior paint with 0.5% by
weight surfactants. VOC = 35 g/L.
Stormer viscosity (KU)
100
95
90
85
80
75
70
65
60
No added
surfactant
Surfynol 420
NPE
OPE-1
OPE-2
OPE-3
OPE-4
Surfynol® 420 surfactant does not affect paint viscosity.
Other surfactants such as nonyl phenol ethoxylates (NPE)
and octyl phenol ethoxylates (OPE-1 through 4) dramatically
reduce viscosity which can cause pigment settling and poor
application with defects such as sags.
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Superwetting Surfactants
Rapidly wet extremely low surface energy substrates (e.g.,
wood, old paint, contaminated surfaces, plastics, etc.)
- Very low dynamic surface tensions
- Extremely fast wetting rates and low contact angles
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Superwetting Surfactants
Commercial paint
0.9% Dynol™ 360
0.9% Dynol™ 800
Vinyl acrylic interior paint applied to a contaminated
surface crawls and has major film defects. The same
paint with 0.9% Dynol™ 360 surfactant and Dynol™
800 surfactant wets the contaminated surface
perfectly.
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Coalescing Surfactants
• Unique surfactant structures
- Enable surface tension reduction at <1 wt.%
- Dynol™ 360 and Surfynol® AD01 surfactants
provide low foam dynamic wetting
- As coalescing surfactants, they also assist in
latex coalescence and film formation (very
unique property)
• Can be used to replace and reduce co-solvent
- Reduce MFFT and / or VOC while maintaining
other properties (e.g., hardness, scrub
resistance, etc.)
- NOT A PLASTICIZER – does not reduce hardness
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Coalescing Surfactants
Coalescence and film formation of a polyurethaneacrylic latex topcoat. Adding 0.9% Dynol™ 360
surfactant eliminates the need for a solvent based
coalescing aid.
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Lowering MFFT with Coalescing
Surfactant – Dynol™ 360 Surfactant
Minimum Film Formation
Temperature (oC)
9
8
7
6
5
4
3
2
1
0
0
0.5
0.8
Weight Percent Coalescing Surfactant
1
Acrylic-polyurethane clear wood coating, 40% volume solids,
VOC = 95 g/L.
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Wetting Agent Selection Guidelines
for Architectural Coatings
Superwetting
Strongest Wetting
Lower water solubility
Strong dynamic
wetting
Dry pigment wetting
No foam
Moderate water
solubility
Moderate dynamic
wetting
Minimal foam
Higher water
solubility
Stronger wetting, Lower Water Solubility, Greater foam control
Efficient wetting, Higher HLB, Less foam control
Dynol™ 800, 980
360 (*)
Surfynol® 104, 420,
440, AD01 (*)
(*) Coalescing surfactants
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Carbowet® GA-210
Surfynol 465, 485, PSA336
Wetting Agent Selection Guidelines
• Match coating requirements to wetting agent
properties:
- Surface tension reduction (type of substrate)
- Dynamic surface tension (application process)
- Foam generation (or defoaming) performance
- Compatibility (solubility and HLB)
- Water resistance (HLB)
- Minimum film formation temperature (MFFT) coalescing surfactant
- Viscosity effects (e.g., interactions with
pigment dispersants, rheology modifiers)
- Environment, health, and safety requirements
(e.g., low/no VOC, HAPs, APE, etc.)
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Dispersants and Surfactants in
Pigment Grinds and Dispersions
Used in Architectural Coatings
Improve pigment dispersion process, pigment
wetting, grinding, color development, dispersion
stability, rheology
Dispersants
Low Foam Dynamic Wetting Agents
Grind Aids
Stabilizing Surfactants (Co-Dispersants)
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Dispersants in Architectural Coatings
• Dispersants are surface active molecules that
orient on the pigment surface and prevents
agglomeration and flocculation through stabilizing
mechanisms
- Specially designed polymers (high performance
dispersants)
- Commodity polymers (acrylic acids, styrene-acrylics,
EO/PO block copolymers) – often used to disperse TiO2
- Some surfactant chemistries (alkylphenol ethoxylate types,
alkyl ethoxylates, alkyl sulfonates, phosphates, etc.)
• A variety of chemistries can be combined to create an
optimally stabilized dispersion
15
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Optimum Dispersant Provides
Maximum Color Development and
Viscosity Stability
Carbon Black Dispersion
Benchmark A
Viscosity: 9350 cps
Benchmark B
Viscosity: gel
Benchmark C
Viscosity: 30 cps
15.0 parts Raven 5000 Ultra III, 31.3 parts Dispersant,
1.0 parts Surfynol DF 75, 52.7 parts water
16
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ZetaSperse 3100
Dispersant
Viscosity: 26cps
F.A.Z.T.  Formulator Assisting
ZetaSperse Tool
• Use F.A.Z.T. or Selector Guide to Choose
Optimal Dispersant for Pigments or Fillers
• An online tool that provides specific dispersant
recommendations and starting point formulations
• Accessible from mobile and desktop devices
• Based on a database of >1500 global pigments
• Formulas calculated from pigment properties,
dispersant attributes and our own extensive
testing and experience
www.FAZT.com
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Surfactant Usage in Grinds and
Dispersions in Architectural Coatings
• Surfactants can enhance dispersion attributes and
improve processing in the three dispersion steps:
1. Wetting Dry Particles
2. Milling/Grinding to Disperse Particles
3. Stabilizing Dispersed Particles
• A variety of benefits can be achieved
- Dry pigment wetting and deaeration
- Milling efficiency and color development
- Letdown compatibility and resistance to shock
and flocculation
- Dispersion viscosity and color stability
18
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Dry Pigment Wetting and Deaeration
• Dynamic wetting agents enable complete wetting
and deaeration of pigments/particles during
dispersion
- Improves cut-in time
- Enables a more efficienct milling process
- Reduces microfoam and optimizes milling density
19
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Dry Pigment Wetting and Deaeration
10 g of P.B. 15:3 added to surface of additive solutions
Styrene-Acrylic Polymeric
Dispersant Only
Same Polymeric Dispersant +
0.3% Dynamic Wetting Agent
20
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Milling/Grinding of the Pigment
• Pigments agglomerate during the drying process,
lowering performance
• Milling is the process by which pigments are
returned to an optimal particle size
milling
process
Requires energy
grinding, shearing, impacting
additives optimize process
21
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Grind Aids Improve Milling Efficiency
• Grind aids can improve milling efficiency through
optimal wetting and dynamic stabilization
- Increased color development, gloss and hiding power
- Reduced milling time; improved energy use
- Dispersion stability and letdown benefits
• Carbowet® GA-series surfactants are designed for
these performance improvements
With Grind
Aid
Greater milling
effectiveness
Without Grind
Aid
Greater milling
efficiency
Jumpstart from
proper deaeration
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Grind Aid Surfactant Can Shorten
Milling Time
0.3 wt.% Surfactant in an acrylic interior flat paint, 100 mm thick film
18
Particle size (D50, microns)
16
14
12
10
No Grind Aid
8
Carbowet GA-210
6
4
2
0
0
5
10
15
20
25
Milling time (minutes)
30
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35
Grind Aid Surfactant Can Enable
Replacement of TiO2 with CaCO3
0.3 wt.% Surfactant in an acrylic Interior Flat Paint, 100 mm thick film
0.98
0.975
Opacity
0.97
0.965
0.96
Control
0.955
0.95
Carbowet GA-100
0.945
Carbowet GA-210
0.94
0.935
0.93
0.925
0
10
20
30
40
50
Ratio of Replaced CaCO3 (%)
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60
Stabilizing Surfactant Dispersants
for Resin-Containing Systems
(Co-Dispersants)
• ZetaSperse® 100-series dispersants are designed to enhance
the stabilization and performance properties of ionic
dispersants
- Enhances letdown compatibility
- Improves dispersion viscosity stability
- Can lower dispersion viscosity allowing higher loadings
• ZetaSperse 170 dispersant
- Amine alkoxylate designed for acidic pigments such as
some carbon blacks and mineral oxides
• ZetaSperse 179 and 182 dispersants
- Specialty high-HLB alcohol alkoxylates
25
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Shock and Letdown Compatibility
• The dispersant plays a large role in preventing
issues when the pigment grind is let down
• Surface tension gradients can drive exchange
between dispersions prior to equilibrium
- This can cause the molecules stabilizing the colorant to
leave the pigment surface and migrate into the white base
paint and vice versa
• Surfactants may “buffer” the system by providing
dynamic stabilization similar to benefits seen in
milling
- Balancing pigment-dispersant differences between the
grind and the letdown formulations
26
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Surfactant Selection Guidelines for
Pigment Grinds and Dispersions
Dry pigment wetting
Faster milling
Color development
Letdown compatibility
Color stability improvement
Viscosity reduction
Stabilization enhancement
Stronger stabilization characteristics; Higher water solubility
Efficient wetting and surface tension reduction; Lower water solubility
Dynamic Wetting Agents
Dynol™ 360
Surfynol® 420,104, AD01
Grind Aids
Carbowet®
GA100, GA210,
GA211, GA221
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Co-Dispersants
ZetaSperse®
170, 179, 182
Surfactant Selection Guidelines for
Pigment Grinds and Dispersions
• With any dispersion, the stabilizing dispersant is
identified first
- F.A.Z.T. and ZetaSperse selectors
• Other additives are selected to optimize the
dispersion properties and process:
- Dynamic wetting for incorporation and milling
- Dynamic stabilization for milling and letdown
compatibility
- Equilibrium stabilization for robust dispersion,
color, and viscosity stability
28
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Defoamers and Deaerators
• Reduce or eliminate foam at surface or in
bulk of coating
• Can affect other properties such as wetting
Conventional defoamers
Molecular defoamers
Deaeators
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Conventional Defoamers
• Organic oils or siloxane. May contain hydrophobic
particles (silica, wax or polyurea)
• Work by an incompatibility mechanism
- Wet across bubble wall surface, weaken wall, bubble breaks
- More incompatible -> stronger defoaming
- More compatible -> weaker defoaming but less chance for
craters
Air phase
Liquid phase
Incompatible
Defoamer Droplet
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Defoaming
Siloxane Defoamer in Exterior Flat
Paint: Optimized Defoaming
Strength and Compatibility
Silcone A
Defoamer
Airase® 5400
Defoamer
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Silcone B
Defoamer
Molecular Defoamers
• Specific Gemini (twin) surfactant structures
• Work by molecular displacement of surfactants
stabilizing foam
- Eliminate microfoam and macrofoam
• “Wetting defoamers” – also providing wetting
agent function
B
B
Spacer
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Deaerators vs. Defoamers
Defoaming
Air phase
Liquid phase
Deaeration
• Defoamers eliminate
macrofoam – bubbles present
on the surface of the paint
• Deaerators eliminate
microfoam (tiny air bubbles
in bulk coating). Are less
prone to diffuse to coating
surface and difficult to
remove.
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Siloxane Deaerator in an AirAssisted Spray Applied coating
100 micron
100 micron
blank
Organic def oamer
100 micron
100 micron
Airase 8070
Traditional PES def oamer
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Defoamer and Deaerator Selection
Guidelines
Pigment Grinds
High PVC
High viscosity
High shear
Thick films
Letdown
Moderate PVC
Moderate shear
Clear coats
Low PVC
Low viscosity
Thin films
Stronger defoaming, less compatible
More compatible, weaker defoaming
Airase® 5100, 5200
Surfynol® DF58
Airase 4500, 5400,
5500
Surfynol DF-58
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Surfynol MD20
Airase 5600, 5700
Defoamer and Deaerator Selection
Guidelines
• Match formulation and application requirements to
defoamer properties and benefits
- What are the paint characteristics:
• Binder, PVC, viscosity, thickness, dry time,
gloss
- What surfactants are being used? Are they
stabilizing foam?
- Where and how does foam occur (grind, mixing,
shaking, application); amount of agitation?
- How is the paint produced?
- How is the coating applied?
- Macrofoam or microfoam?
- Are silicones acceptable?
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