Presented by Ahren Olson Covestro LLC Introduction This presentation will provide an general overview on protective coatings used in the industrial and marine industry Protective Coatings The following coatings are used to mitigate corrosion on structures in the industrial and marine industry ID: 511270
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Slide1
Performance Properties of Protective Coatings
Presented by: Ahren Olson, Covestro LLCSlide2
Introduction
This presentation will provide an general overview on protective coatings used in the industrial and marine industrySlide3
Protective Coatings
The following coatings are used to mitigate corrosion on structures in the industrial and marine industry:
Acrylics (Waterborne)
Alkyds
Epoxies
Polyurethanes
Polyureas
Polyaspartics
Polysiloxanes
Zinc rich coatingsSlide4
Waterborne Acrylics
Acrylic chemistry is very versatile
WB acrylics are thermoplastic polymers and “cure” through solvent evaporation, particle deformation, and coalescence.
Self-crosslinking products also exist and can provide additional physical properties
It is important to understand the minimum film forming temperature of the productsSlide5
Waterborne Acrylics
Disadvantages
Free/thaw stability of liquid product
Lengthened drytime below 50F and at elevated humidity
Advantages
1K
Low VOC
Weatherable finish
Easily
recoatable
Great for overcoatingSlide6
Applied to a wide variety of substrates such as metal, wood, concrete, and galvanizing.Applied using standard spray, brush, and roll methods
A few end use applications: exterior of storage tanks, steel bridge girders, exterior of rail cars, and concrete retaining walls
Waterborne AcrylicsSlide7
Can be used DTM for less aggressive environmentsCan also be applied over zinc rich primers in two and three coat systems for more aggressive environments
Waterborne AcrylicsSlide8
Waterborne Acrylics
Optimum film quality requires careful polymer (latex) design and choice of formulation additives
There are several SSPC performance based paint standards for WB acrylicsSlide9
SSPC-Paint 23
This standard covers performance requirements for
an air
drying, ready-mixed, latex primer for blast cleaned
steel. It
is intended for use as the prime coat of a coating
system consisting
of one or two coats of this primer and one or
two coats
of a compatible topcoatSlide10
SSPC-Paint 24
This
specification
covers an air drying,
ready-mixed, water-borne semi-gloss
latex paint for use on metal
surfaces primed
with a primer conforming to SSPC-Paint 23. It
is intended
for use as a topcoat of a water-borne coating
system consisting
of two coats of primer and one or two coats of
this water-borne
topcoat.Slide11
Alkyds
Alkyds are ester based polymers and are modified by some degree with an oil or fatty acid
Short oil
Dries more rapidly, develops better gloss, hard films
OEM applications, typically sprayed or dip coated
Medium oil
Dry more slowly than short oil alkyds and are slightly softer films
OEM, Architectural, and industrial maintenance applications
Long oil
Slowest to dry and softest films
Architectural, and industrial maintenance applications
Alkyds
oxidatively
cure through the reaction with oxygen from the airSlide12
Alkyds
Disadvantages
VOC can be high
Cannot be applied directly to zinc (primers/galv.) or concrete
Embrittlement over time
Lower film build per coat
Advantages
1K
Surface tolerant
Fast drying
Universal primers
Low costSlide13
Alkyds
Alkyd resin can be enhanced by incorporating a variety of synthetic resins
Phenolic alkyds
Silicone alkyds
Urethane alkydsSlide14
Phenolic Alkyds
Fast curing with good water/corrosion resistance, improved adhesion
Used as lacquer-resistant shop primers.Slide15
Urethane Alkyds
Typically 15-30% of the dibasic acid is substituted by urethane modification in manufacturing process
Fast-drying, good UV resistance, improved abrasion resistance, and better alkali resistance
Wide variety of uses in both interior and exterior service
Safety colors
Structural steel
Wood flooringSlide16
Silicone Alkyds
Best color and gloss retention within alkyd family of coatings
Typically around 30% silicone modification
Used as high quality finish coats
Structural steel
Tanks
BuildingsSlide17
Epoxy Coatings
Most commonly used coating in the protective coating market
Reaction of an epoxy resin an amine function resin
Incredibly versatile chemistry for protective coatings
Multitude end use applications covering both immersion and atmospheric service (primers, intermediate, and finish coats)Slide18
Epoxy Coatings
Disadvantages
Poor UV resistance
Poor low temperature cure
Tend to be inflexible
Limited recoat window
Advantages
Excellent adhesion
Chemical resistance
Corrosion resistance
Thick film possible
High temperature resistanceSlide19
Epoxy Coatings
By utilizing available variations in epoxy resins and curing agents, coatings with a variety of properties have been developed to meet a variety of end use needs
Epoxy resins
Bisphenol
-A epoxy
Bisphenol-F epoxy
Novolac epoxy
Common amine resins
Polyamide
Aliphatic aminesSlide20
Bisphenol-A; Bisphenol-F; and Novolac Epoxies
Diglycidyl
ether of
bisphenol
A
(DGEBA
)
General purpose resins
Diglycidyl
ether of
bisphenol
F
(
DGEBF
)
Lower viscosity, blended with DGEBA to prevent crystallization
Novolac
resins
Excellent chemical and heat resistanceSlide21
Polyamide-Cured Epoxy
When compared to amine-cured epoxy, they have better:
Water resistance
Flexibility
Less tendency to amine blush
Longer pot-lifeSlide22
Polyamide-Cured Epoxy (cont’d)
Have greater amounts of solvent (VOCs), longer cure times (may require an induction period), and less chemical resistance than amine cured epoxiesSlide23
Amine-Cured Epoxies
When compared to polyamide-cured epoxies are:
More chemically resistant and faster curing
Have lower viscosities
Form tougher films
Shorter pot life
Tendency to amine blush
Less tolerant mixing ratiosSlide24
SSPC-Paint 42
This standard contains performance requirements for a two-component epoxy
polyamide/
polyamidoamine
primer coating for use as a primer on blast cleaned steel
surfacesSlide25
Polyurethanes
Formed by the reaction of a polyisocyanate and an OH-functional polyol
Most commonly used UV resistant finish coat in aggressive exposures
Two varieties
Aromatic
AliphaticSlide26
Aliphatic Polyurethanes
Disadvantages
Sensitivity to moisture during cure
Out gassing when over applied
Difficult to overcoat weathered urethanes
Advantages
UV resistance
Abrasion resistance
Chemical resistance
Fast drying
Cost : performanceSlide27
Aromatic Polyurethanes
Disadvantages
Poor UV resistance
More reactive to water can lead to greater outgassing
Advantages
Improved physical properties
Fast curing
Chemical resistance
Immersion serviceSlide28
Polyurethane Coreactants
Polyethers
Better resistance to hydrolysis, but worse weathering
Used on roofs and secondary containment structures where water accumulates
Acrylics
Best color and gloss retention
Most often used polyol used for aliphatic polyurethanes
Polyesters
Best chemical and abrasion resistanceSlide29
SSPC-Paint 36
Covers the requirements for high performance 2K, UV stable polyurethane topcoats that are suitable for varying exposures and environmental zonesSlide30
Moisture Curing Polyurethanes
1K polyurethanes that cure through the reaction of the polyisocyanates with moisture to form a polyurea film
Used as sealers, zinc rich primers, intermediate, and finish coats
Found use in areas of high humidity
Bridges in Northwest US
Water treatment plants on sweating pipesSlide31
Moisture Cure Polyurethanes
Disadvantages
Out gassing when over applied
Thinner film build that 2K aliphatic urethanes
Shelf life / can stability
Advantages
1K paint
UV resistance
Surface tolerant
Low temp cure
Fast dryingSlide32
SSPC-Paint 38
This standard contains performance requirements for a high-performance, single-component, moisture-curing UV-stable polyurethane
topcoat. The
coating is intended to be used as a topcoat that provides good color and gloss
retentionSlide33
SSPC-Paint 40
This specification contains performance requirements for an organic zinc-rich moisture-cure polyurethane
primerSlide34
SSPC-Paint 41
This specification contains performance requirements for a moisture-cured aromatic polyurethane coating with a thermoset binder and
micaceous
iron oxide pigment
reinforcementSlide35
Polyureas
Cured by the reaction of a
polyisocyanate
and an amine resin
Two distinct types of chemistry
Aromatic
Aliphatic
Pure polyurea and urethane hybrids available
Plural component equipment application
SSPC-Paint 45Slide36
Polyureas
Disadvantages
Plural component equipment
Deep angular surface profile required
Aromatic not UV resistant
Advantages
Abrasion resistance
Chemical resistance
Very fast drying – return to service
Thick filmsSlide37
SSPC-Paint 45
This standard contains minimum
performance requirements
for two types of two-component
polyurea
coatings
and two types of
polyurea
/polyurethane
hybrid coatings
evaluated by laboratory testing.Slide38
Aromatic Polyureas
Better chemical resistance than aliphatic
Chalk and yellow in sunlight, but little change to other physical properties
Numerous uses
Truck bed liners, secondary containment, buried pipe coatings
Good chemical resistance to a number of industrial chemicals and hydrocarbonsSlide39
Aliphatic Polyureas
Aliphatic polyisocyanates used
Stable in sunlight
Will be applied over an aromatic polyurea when UV-resistance is needed
Still require plural component equipment for applicationSlide40
Polyaspartics
Reaction between an aspartic ester resin and an aliphatic polyisocyanates
Can be applied using by standard airless equipment as well as brush and roll
Properties are similar to those of polyurethane coatings
Used as finish coat in two-coat systems or even as DTM in less corrosive environmentsSlide41
Polyaspartics
Disadvantages
Acid resistance
Limited recoat window compared to urethanes
Humidity effects cure rate
Advantages
Fast cure with potlife
UV resistant
Thicker films up to 20 mils
Edge retentionSlide42
Polyaspartics
Higher film builds allow the reduction in coating layers while providing the required corrosion protection
Two-coat systems with zinc rich primer
DTM in less aggressive environmentsSlide43
SSPC-Paint 39
This specification contains performance
requirements for
a two-component,
weatherable
polyurea
topcoatSlide44
SSPC-Paint 43
This standard contains performance requirements for a two-component direct-to-metal aliphatic
polyurea
coating with a dry-to-handle time ranging from 30 minutes to 2 hours as determined using ASTM D
1640Slide45
Polysiloxanes
Any polymeric structure that contains repeating silicon-oxygen groups in the backbone, side chains, or crosslinks regardless of the substitution on the silicon atom
Include coating types based on inorganic siloxane and organic-inorganic siloxane polymer hybridsSlide46
Polysiloxanes
C-C bond strength of 83 Kcal/mole
Si-O bond strength of 108 Kcal/mole
The stronger bond strength provides the basis for improved durability and heat resistance
Si-O is UV resistant; already oxidized; not combustibleSlide47
Inorganic Siloxanes
Polysiloxane coatings based on pure inorganic siloxane binder are:
Can cure at ambient temperatures,
Some can be applied to hot piping
High solids
Excellent temperature resistance (>1000F)
Good chemical resistance
Can be rather brittle
UV resistanceSlide48
Organic-Inorganic Siloxane Hybrid
Organic modification for improved flexibility
Acrylic
Epoxy
Predominant use would be as light stable finish coats
High solids ~80% solids+
Low VOC
Very good
weatherabilitySlide49
Organic Modified Polysiloxanes
Disadvantages
Humidity required for cure, typically 50%+
Embrittlement at high film builds
Cost
Advantages
Improved flexibility
Excellent UV resistance
Cleanability
No outgassing during cureSlide50
Organic Modified Polysiloxanes
Used as an alternative to polyurethane finish coat in three coat systems
Also used as high build finish coat in two-coat system over zinc rich primerSlide51
Zinc Rich Coatings
Two main classes of zinc rich coatings
Inorganic: ethyl silicate binders
Organic: epoxy or urethane binders
Galvanic protection of steel substrate
Exception track record of long term corrosion protectionSlide52
Inorganic Zinc Rich Primers
Disadvantages
Cure time heavily dependent on humidity
Typically 16-24 hours wait prior to
topcoating
Mud cracking at higher film builds
Advantages
Enhanced corrosion resistance
Can be used as a stand along coating
Fast drying for productivity in shop Slide53
Organic Zinc Rich Primers
Disadvantages
Slightly less performance than IOZ
Lower resistance to heat versus IOZ
Epoxy zinc rich can require sweat-in time
Advantages
Much faster recoat time than IOZ
Resistant to mud cracking
Lesser cleanliness requiredSlide54
SSPC-Paint 20
This
specification
covers two types of highly
pigmented zinc-rich
coatings that are uniquely
defined
by their
capabilities for
protecting steel exposed at
film
discontinuities such
as narrow
scratches
and
holidays.Slide55
SSPC-Paint 29
This specification covers highly pigmented primers
that contain
zinc dust as the major pigment component (
minimum 65
% by weight in the dry film) and are defined by their
ability to
protect ferrous substrates. Individual products
meeting minimum performance requirements
of this standard may
vary in
formulation, raw materials, and application
characteristics. Slide56
General Comparison Chart – Atmospheric Exposure
Coating Type
Color and Gloss Retention
Surface Tolerant
Abrasion Resistant
Chemical
Resistant
Alkyd
+
++
Epoxy
-
+
+++
Urethane
(aliphatic)
++
+
+
MCU
++
+
+
+
Waterborne
Acrylic
++
+
Polyaspartic
++
+
+
Polyurea (aromatic)
-
+
++
Organic
modified polysiloxane
+++
+
++Slide57
Summary
When selecting a coating for application it is important to identify the service environment, performance requirements, and type of structure and substrate in order to achieve optimum performance