Industrial Strength:
Benefits of Waterborne Acrylic Coatings
Mary Rose Correa and Leo Procopio
December 15, 2015
Dow.com
Agenda
Market Perspective
• Market background
• Trend analysis
Waterborne Acrylics 101: The Basics
•
•
•
•
What is an acrylic?
Benefits & Challenges of WB
Film formation
Performance & Recent Advances in the State-of-the-Art
Industrial Applications with Waterborne Solutions
• Examples of where WB Acrylics are used in Industrial applications
2
Market Perspective
3
Perspective: Why are we talking about WB?
U.S. Coatings Market
U.S. Coatings Market (Gallons Consumed)
U.S. Coatings Market by Technology
4%
WB
5%
24%
53%
2%1%
SB
Special Purpose
23%
Powder
OEM
33%
Architectural
55%
100% Solid
E-coat
Radcure
2011 Consumption
WB by Segment
•
1.4 Billion gallons
•
Architectural – 72%
•
Valuation of $23.1 Billion
•
Special Purpose – 18%
•
OEM – 10%
•
60% of value is from Industrial segments
Source: The US Paint & Coatings Industry 2011-2016; Kusumgar, Nerfli & Growney, 2012
4
Why the drive towards waterborne coatings?
• Regulations and specifications around the globe
• Volatile Organic Compounds (VOCs)
• EPA, SCAQMD (California), OTC, CARB, etc.
• Hazardous Air Pollutants (HAPs)
• EPA
• Interior air quality
• LEED, Greenguard, BIFMA, etc.
• End-user demands for greener / more sustainable products
• Demand for coatings with lower odor, lower flammability
5
Benefits & Challenges of Waterborne Coatings
Benefits
 Low VOC = less impact on environment
 Low odor
 Less concern over worker exposure to
hazardous solvents
 Better “cycle time” for various trades
 Lower or no risk of fire from handling
flammable solvents
 Easy and safer cleanup
Challenges
• Application window, i.e., length of
painting season
• Drying rate dependent on humidity
• Reduced water resistance
• Surfactants
• Salts
• Often reduced substrate wetting
• Higher surface tension of water
 Less waste and hazardous disposal
• Open time
 Ease of use
• Film formation
 Proven performance in real world
applications
• Perceived lower performance vs SB
coatings
6
Primary Types of Waterborne Coatings
Acrylic and Vinyl-acrylic Latex
Epoxy Dispersions
Polyurethane Dispersions (PUD’s)
2K Polyurethanes
Water Reducible Alkyds & Alkyd Dispersions
Zinc Rich
• Inorganic Silicate
• Organic (Epoxy)
7
Waterborne Acrylics in Industrial Coatings
Field-applied industrial maintenance coatings for metal and concrete
Traffic and roadmarking paints
Elastomeric roof coatings
General industrial finishing
Plastic coatings
Concrete and metal roof tiles
Fiber cement siding
Wood and wood composite coatings: e.g., cabinets, furniture, joinery
Coil coatings
8
Industrial Maintenance Applications Using WB Acrylics
Storage tanks
Bridges
Shipping
containers
Railcars
Structural
steelwork
Commercial
Architectural
Metal buildings
Water towers
Pipes
9
Industrial Maintenance Coatings Market: Technology Distribution
Segmentation of U.S. Industrial Maintenance Coatings Market by Technology:
Volume of Coatings (2010)
WB Alkyd
2%
Other
13%
SB Alkyd
10%
WB Acrylic
24%
SB and 100% solids
Epoxy
32%
Industrial Maintenance
Coatings market in the
US was estimated at
52 MM gallons and
$817 MM for 2010
SB Polyurethane
14%
WB Epoxy
3%
SB Acrylic
1%
WB Polyurethane
1%
Source: US Paint & Coatings Industry Market Analysis (2010-2015), American Coatings Association, 2012
10
Key Trends and Drivers in Industrial Space
Sustainability/Regulations
• Trend toward WB, high solids
• VOC/odor reduction
• Carbon footprint
• Human health & safety
Performance
• Surface compatibility
• Improved durability/resistance
• Extreme environment corrosion protection
Cost Effectiveness
• Reduced prep, application time/number
of coats
• Extended pot life
• Optimized processing
11
Waterborne Acrylics
101: The Basics
12
Acrylic Polymer Technology
• Acrylics are based on esters of acrylic and methacrylic acid, but can
also include other non-acrylic monomers such as styrene and vinyl
acetate
• Solventborne and waterborne acrylic polymers are available
• First uses date to the late 1920’s, when acrylic polymers were used in
making automobile safety glass
Acrylates
R = Et, Bu, etc.
Methacrylates
R = Me, Bu, etc.
Styrene
Vinyl Acetate
13
Acrylic Polymer Formation
Vinyl group
• Acrylics are typically made via free radical polymerization of the
unsaturated vinyl group
• Process can occur in solvent or water
• Results in a high molecular weight polymer
14
Variety of Acrylic Monomers are Available
• A wide range of acrylic monomers are available
• They vary in hydrophobicity, Tg (hardness),
functionality for adhesion or reactivity, etc.
• Acrylic polymers can be tailored
for a wide range of properties
R"
H
Me
Et
n-Bu
i-Bu
2-ethylhexyl
Acrylates (R' = H)
Name
acrylic acid
methyl acrylate
ethyl acrylate
butyl acrylate
isobutyl acrylate
2-ethylhexyl acrylate
Metha
Tg (°C)
110
8
-22
-54
-53
-65
N
metha
methyl m
ethyl m
butyl m
isobutyl
15
Uses of Acrylic Polymer Technology
• Paints and coatings
• Motor oil additives
• Adhesives
• Leather tanning and finishing
• Caulks and sealants
• Plastic, e.g., Plexiglas
• Scale inhibitors for water systems
• Personal care products
• Detergent additives
• Cement modifiers
• Textile finishes
• Floor polishes
Global production of
monomers:
Acrylic acid
• 5 million metric ton
• 75% for super-absorbant
Acrylate esters
• 4.3 million metric tons
• 36% into coatings
Methyl methacrylate
• 3 million metric tons
• (20% into coatings)
• Paper coatings
16
Brief History of Acrylic Coatings
1930’s
Solventborne acrylics first used in coatings
1940’s
Solvent-based oil and alkyd paints dominate the architectural market
1948
First waterborne latex paint based on SBR
1950’s
Commercial use of SB acrylics grew significantly
1955-1971 SB thermoplastic acrylics used on all U.S. made GM automobiles
1953
First WB acrylic latex introduced for interior architectural coatings and masonry
1961
First WB acrylic specifically for exterior architectural coatings
1970’s
WB acrylics with good adhesion to chalky substrates, stain-blocking primers
1980’s
Improved WB acrylics for metal and masonry substrates, first hollow sphere
pigments, high gloss trim paints, multi-lobe technology
17
Brief History of Acrylic Coatings
1990’s Acrylics capable of interior/exterior performance, self-crosslinking acrylics, low
solvent binders, improved hollow sphere pigments, improved corrosion resistance
Today
WB acrylics dominate the architectural market, and are heavily utilized in industrial
painting. Trends are to lower VOC and higher performance.
Acrylic Coatings Market Size:
By volume, acrylics are the leading technology used in coatings
• ~25% of all coatings volume globally
• 6 million metric tons of finished coatings
• $20 billion value
18
Why Use Acrylics in Paints and Coatings?
• Excellent resistance to ultraviolet light
(UV), which translates into excellent
exterior durability
• Color and gloss retention
• Maintain clarity
• Resistance to chalking
• Toughness
• Maintain flexibility and resistance to
embrittlement
• Resistant to grain cracking over wood
• Hydrolytically stable
• Wide range of compositions attainable
(i.e., can tailor composition for various
applications)
19
What are Waterborne Acrylic Coatings?
• Paints and coatings based on WB acrylic
polymers and co-polymers (i.e., acrylic latex
or acrylic emulsion polymers)
• Vinyl-acrylics are common copolymers of
acrylic monomers with vinyl acetate
• Most commonly associated with architectural
coatings, but are used in numerous industrial
paints and coatings
Two Types of Coatings Systems
One-component
• Thermoplastic acrylics
• Self-crosslinking thermoplastic acrylics
• Elastomeric acrylics
Two-component
• Acrylic / epoxy
• Acrylic polyurethane
20
Types of Waterborne Polymers
Carrier:
Mol. Wt.
Latex
Dispersion
Water-reducible
Water
High
Water
Low-Med
Solvent
Low
21
What is an acrylic latex polymer?
• Synthesized by emulsion polymerization of acrylic monomers
• Results in a dispersion of discrete, colloidal particles in water
• Each particle contains many high MW polymer chains
Appearance:
Like milk, translucent to
opaque white, but dries
to a clear film
Particle size:
50 – 500 nanometers,
usually spherical
Solids:
30 – 65% by weight
22
How do WB polymers differ from SB polymers?
Type
Latex polymer
Solution polymer
Carrier
Water
Various solvents
MW
High (up to 1 million)
Low (5 - 100K)
Viscosity
Dependent on particle size
Dependent on MW
23
Film formation process
• Film formation:
Conversion of a coating film from a liquid or fluid form into a solid.
Entanglement of polymer chains gives the film cohesion and strength.
• The film formation process is one of the main differences between WB
coatings and SB coatings
• It is key to understanding performance of WB coatings and some of the
reasons for failures
24
Film formation process
• The goal of film formation is to form a “good” film
• What is a “good” film?
• Defined by the end use of the film or coating:
•
•
•
•
•
•
•
Block resistance
Tensile strength
Elongation
Barrier properties
Stain resistance
Corrosion resistance
Water resistance
25
Film formation for solvent borne coatings
Solvent evaporation
and polymer entanglement
Crosslinking
Examples of
crosslinking would be
reactions via oxidation
(e.g., alkyds) or via
crosslinkers (e.g., 2K
epoxies and
polyurethanes
26
Film formation for latex coatings
Stage 1:
Coating applied to substrate
Stage 2:
Close packed array w/
water-filled interstices
Stage 3:
Compacted array of
deformed particles
Stage 4:
Loss of particle boundaries
Homogeneous film
Water evaporation
and latex particle
packing
Water diffusion
and particle
deformation
Polymer chain
interdiffusion
27
Factors affecting latex film formation
Latex polymer variables
• Tg - Glass transition temperature
• Molecular weight
• Particle size
Formulation
• Coalescents & Plasticizers
• Pigment
Drying Environment
•
•
•
•
Temperature
Humidity
Air Velocity
Substrate Porosity
28
Conditions leading to poor film formation
If latex particles don’t coalesce properly, microscopic voids and
channels will be present, and lead to poor barrier properties. In worst
case, this leads to cracked and friable film.
Humidity:
• Too high application humidity can cause coalescents to leave before water.
When water finally evaporates, there is not enough coalescent to allow latex
particles to deform.
• Air movement helps alleviate this potential problem.
• Manufacturers usually recommend a maximum humidity of 85 – 90%.
29
Conditions leading to poor film formation
Temperature:
• Latex polymers are often formulated with coalescent to form a film within a
certain temperature range
• Recommended range is usually between 45 – 110°F
• Too low application T or formulation with too little coalescent/plasticizer leads to
incomplete coalescence
• Too high application T leads to water and coalescent flashing off before
particles coalesce
30
The Importance of Film Formation:
Effect of Coalescent Level on Corrosion Resistance
200 hr salt spray (ASTM B117) on blasted hot rolled steel
18 PVC Gloss white acrylic latex DTM formula
Coalescent level:
5%
10%
15%
20%
31
Important factors for success
Coating
-Choice of coating type
-Quality formulation
-Performance (e.g.,
adhesion)
-Surface wetting
-No defects
Application
-Environmental
conditions
-Prevent defects
(e.g., foam)
-Proper film
thickness
Surface Prep
-Anchor profile
-Cleanliness
-Remove
contaminants
32
Industrial Applications
with Waterborne Solutions
33
Types of Waterborne Acrylic Coatings Available
Waterborne acrylic resins are used in the following types of industrial
maintenance and commercial architectural coatings:
Primers
• Wash primers
• Anti-corrosive primers
• Block fillers
• Masonry primers
Direct-to-substrate finishes
• DTM finishes
• Elastomeric wall & roof coatings
Topcoats
• Gloss to flat sheens
• Clear or pigmented
Functional coatings
• Thermal insulation
• Sound Damping
• Formaldehyde abatement
34
Service Environments for Waterborne Acrylics
Waterborne acrylic coatings, particularly the 1K variety, are usually used in
service environments defined as low to medium duty:
• ISO 12944 corrosion categories: e.g., C1 - C3
• SSPC Environmental Zones: e.g.,
• 1A (interior, normally dry)
• 1B (exterior, normally dry)
• 2A (Frequently wet by fresh water)
35
Industrial Uses of WB Acrylics: Bridge Coatings
Where Used?
• Steel and concrete bridges –
primers and topcoats
• Often used over primers of
other chemistry, e.g., Zn rich
• Specified and used by states
such as CA, GA, NC, FL, etc.
Key Attributes
• Low VOC
• Color and Gloss retention
• 1K ease of use
• Barrier properties – corrosion
resistance
36
Industrial Uses of WB Acrylics: Rail & Container
Where Used?
• Boxcars, hopper cars,
gondola cars – exterior DTMs
• Shipping containers –
primers/topcoats
Key Attributes
• Low VOC
• Fast dry
• Gloss
• Color and Gloss retention
• 1K ease of use
• Barrier properties – corrosion
resistance
37
Recent Advances in WB Acrylic Protective Coatings:
DTM Coatings with lower VOC and less corrosion
The challenge for WB Acrylic DTM coatings
has been to improve barrier properties (i.e.,
corrosion resistance) while also lowering VOC
Solution
• Improve pigment distribution in dry coating by
enhancing the latex-pigment interaction in the wet
paint via formation of latex-pigment composites
• Optimize morphology of latex particles to give good
film formation with minimal impact on hardness
Result
• WB Acrylic DTMs with excellent corrosion resistance
and VOC < 50 g/L
38
Film Formation with Latex-Pigment Composites
•
•
Optimizing pigment dispersion through formation of
latex-pigment Composite Particles in the wet state
Composite particle
formation
39
Block Resistance
Hardness properties such as block resistance can be difficult to maintain when
lowering VOC levels.
1 Day Block Resistance
8
7
6
5
4
3
2
1
0
Low VOC DTM
Commercial #1 <200 VOC
1 Day, 30 min. Oven Block
Commercial #2 <50 VOC
Commercial #3 <100 VOC
1 Day, Room Temp. Block
40
Corrosion Resistance
1000 Hours Salt Spray Exposure over Cold Rolled Steel
New technology
8% coalescent
< 50 g/L
Commercial DTM
#1
<200 VOC
Stopped @ 576
hours
Commercial DTM
#2
<50 VOC
Stopped @ 576
hours
Commercial DTM
#3
<100 VOC
41
Industrial Uses of WB Acrylics: Commercial Architecture
Where Used?
• Interior and exterior walls –
concrete, drywall
• DTMs for steel structures
• Roof coatings
• Interior floor coatings
Key Attributes
• Low VOC, low odor
• Color and Gloss retention
• 1K ease of use
• Barrier properties – corrosion
and water resistance
• Chemical / solvent resistance
• Abrasion resistance
42
Recent Advances in WB Acrylic Commercial Coatings:
Wall Coatings to Improve Indoor Air Quality
• Indoor Air Quality is a topic of increased
interest for both residential and commercial
buildings
• Increased awareness by builders and
architects in considering the comfort, health
and wellness of building occupants
• Wall coatings represent a large surface area
within a building – can a functional coating
be used to improve the indoor air quality?
• The new technology is for wall coatings and
based on a WB acrylic polymer with
functionality that reacts with formaldehyde
and irreversibly removes it from the air
43
Mechanism: How can a coating affect indoor air quality?
1. Formaldehyde make contact with formaldehyde abatement functionality
2. Reaction permanently removes formaldehyde
3. Transforms indoor air pollutant into harmless vapor
44
Conclusions
• Waterborne acrylics are one of the major technologies used in Industrial and
Commercial Coatings
• Wide range of compositions and performance is available for the varying application
requirements
• Understanding the film formation mechanism of latex coatings is a key to the
successful use and ultimate performance of WB Acrylics
• New advances are pushing the limits on performance, such as:
• Corrosion resistance
• Low VOC capability
• Added functionality, such as formaldehyde abatement
• WB Acrylics are being used successfully in many industrial applications, and
offer a safer and more sustainable alternative to traditional solventborne
coatings.
45
Q&A
FOR A COPY OF THE PRESENTATION, PLEASE CONTACT:
CoatingMaterials@dow.com
46
Disclaimer
HANDLING PRECAUTIONS
PRODUCT STEWARDSHIP
CUSTOMER NOTICE
Before using any product mentioned herein, consult the product’s Material Safety Data Sheet
(MSDS)/Safety Data Sheet (SDS) for details on product hazards, recommended handling
precautions and product storage.
Dow has a fundamental concern for all who make, distribute, and use its products, and for the
environment in which we live. This concern is the basis for our product stewardship philosophy by
which we assess the safety, health, and environmental information on our products and then take
appropriate steps to protect employee and public health and our environment. The success of our
product stewardship program rests with each and every individual involved with Dow products - from
the initial concept and research, to manufacture, use, sale, disposal, and recycle of each product.
Dow strongly encourages its customers to review both their manufacturing processes and their
applications of Dow products from the standpoint of human health and environmental quality to
ensure that Dow products are not used in ways for which they are not intended or tested. Dow
personnel are available to answer your questions and to provide reasonable technical support. Dow
product literature, including safety data sheets, should be consulted prior to use of Dow products.
Current safety data sheets are available from Dow.
NOTICE: No freedom from infringement of any patent owned by Dow or others is to be inferred.
Because use conditions and applicable laws may differ from one location to another and may change
with time, Customer is responsible for determining whether products and the information in this
document are appropriate for Customer's use and for ensuring that Customer's workplace and
disposal practices are in compliance with applicable laws and other government enactments. The
product shown in this literature may not be available for sale and/or available in all geographies
where Dow is represented. The claims made may not have been approved for use in all countries.
Dow assumes no obligation or liability for the information in this document. References to “Dow” or
the “Company” mean the Dow legal entity selling the products to Customer unless otherwise
expressly noted. NO WARRANTIES ARE GIVEN; ALL IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY
EXCLUDED.
NOTICE: If products are described as "experimental" or "developmental": (1) product specifications
may not be fully determined; (2) analysis of hazards and caution in handling and use are required; (3)
there is greater potential for Dow to change specifications and/or discontinue production; and (4)
although Dow may from time to time provide samples of such products, Dow is not obligated to
supply or otherwise commercialize such products for any use or application whatsoever.
47
Thank
You
For additional information, please contact coatingmaterials@dow.com
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow
48