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Industrial Strength: Benefits of Waterborne Acrylic Coatings

Mary Rose Correa and Leo ProcopioDecember 15, 2015

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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

Market Perspective

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Perspective: Why are we talking about WB?U.S. Coatings Market

2011 Consumption• 1.4 Billion gallons• Valuation of $23.1 Billion

• 60% of value is from Industrial segments

WB by Segment• Architectural – 72%• Special Purpose – 18%• OEM – 10%

24%

23%53%

U.S. Coatings Market (Gallons Consumed)

Special PurposeOEMArchitectural

55%33%

5%

4% 2%1%U.S. Coatings Market by Technology

WBSBPowder100% SolidE-coatRadcure

Source: The US Paint & Coatings Industry 2011-2016; Kusumgar, Nerfli & Growney, 2012

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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

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Benefits & Challenges of Waterborne Coatings

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

• Open time• Film formation• Perceived lower performance vs SB

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 Less waste and hazardous disposal Ease of use Proven performance in real world

applications

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Primary Types of Waterborne Coatings

Acrylic and Vinyl-acrylic Latex

Epoxy Dispersions

Polyurethane Dispersions (PUD’s)

2K Polyurethanes

Water Reducible Alkyds & Alkyd Dispersions

• Inorganic Silicate• Organic (Epoxy)

Zinc Rich

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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

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Industrial Maintenance Applications Using WB Acrylics

Storage tanks Bridges Railcars Metal buildings Commercial Architectural

Shipping containers

Structural steelwork Water towers Pipes

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SB and 100% solidsEpoxy32%

SB Polyurethane14%

WB Acrylic24%

SB Alkyd10%

Other13%

WB Epoxy3%

WB Polyurethane1%

SB Acrylic1%

WB Alkyd2%

Industrial Maintenance Coatings Market: Technology DistributionSegmentation of U.S. Industrial Maintenance Coatings Market by Technology: Volume of Coatings (2010)

Industrial Maintenance Coatings market in the US was estimated at 52 MM gallons and $817 MM for 2010

Source: US Paint & Coatings Industry Market Analysis (2010-2015), American Coatings Association, 2012

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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

Waterborne Acrylics 101: The Basics

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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

AcrylatesR = Et, Bu, etc.

MethacrylatesR = Me, Bu, etc.

Styrene

H2CO

R

O

H

H2CO

R

O

CH3

Vinyl Acetate

H2C OC

CH3

H O

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Acrylic Polymer Formation

• 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

H2CO

R"

O

R'

H2C C CH2

R'

CO2R"

C CH2

R'

CO2R"

C

CO2R"

R'Vinyl group

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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

H2CO

R"

O

R'

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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• Paper coatings

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)

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

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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.

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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

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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)

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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 SystemsOne-component• Thermoplastic acrylics• Self-crosslinking thermoplastic acrylics• Elastomeric acrylics

Two-component• Acrylic / epoxy• Acrylic polyurethane

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Types of Waterborne Polymers

Latex Dispersion Water-reducible

Carrier: Water Water SolventMol. Wt. High Low-Med Low

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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

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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

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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

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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

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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

Film formation for solvent borne coatings

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Water evaporation and latex particle packing

Water diffusion and particle deformation

Polymer chain interdiffusion

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 boundariesHomogeneous film

Film formation for latex coatings

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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

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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%.

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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

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The Importance of Film Formation: Effect of Coalescent Level on Corrosion Resistance

200 hr salt spray (ASTM B117) on blasted hot rolled steel18 PVC Gloss white acrylic latex DTM formula

Coalescent level: 5% 10% 15% 20%

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Important factors for success

Coating-Choice of coating type

-Quality formulation-Performance (e.g.,

adhesion)-Surface wetting

-No defects

Surface Prep-Anchor profile-Cleanliness

-Remove contaminants

Application-Environmental

conditions-Prevent defects (e.g.,

foam)-Proper film thickness

Industrial Applications with Waterborne Solutions

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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

Types of Waterborne Acrylic Coatings AvailableWaterborne acrylic resins are used in the following types of industrial maintenance and commercial architectural coatings:

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Service Environments for Waterborne AcrylicsWaterborne 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)

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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

Industrial Uses of WB Acrylics: Rail & Container

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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

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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

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• Optimizing pigment dispersion through formation of • latex-pigment Composite Particles in the wet state

Composite particle formation

Film Formation with Latex-Pigment Composites

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Block ResistanceHardness properties such as block resistance can be difficult to maintain when lowering VOC levels.

Low VOC DTM Commercial #1 <200 VOC Commercial #2 <50 VOC Commercial #3 <100 VOC0

1

2

3

4

5

6

7

81 Day Block Resistance

1 Day, 30 min. Oven Block 1 Day, Room Temp. Block

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Corrosion Resistance1000 Hours Salt Spray Exposure over Cold Rolled Steel

Commercial DTM #3

<100 VOC

Commercial DTM #2

<50 VOCStopped @ 576

hours

Commercial DTM #1

<200 VOCStopped @ 576

hours

New technology8% coalescent

< 50 g/L

Industrial Uses of WB Acrylics: Commercial Architecture

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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

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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

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Mechanism: How can a coating affect indoor air quality?

1. Formaldehyde make contact with formaldehyde abatement functionality2. Reaction permanently removes formaldehyde3. Transforms indoor air pollutant into harmless vapor

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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.

Q&A

FOR A COPY OF THE PRESENTATION, PLEASE CONTACT:CoatingMaterials@dow.com

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