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Performance Properties of Protective Coatings Performance Properties of Protective Coatings

Performance Properties of Protective Coatings - PowerPoint Presentation

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Performance Properties of Protective Coatings - PPT Presentation

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

coatings resistance paint performance resistance coatings performance paint sspc zinc coating epoxy rich requirements cure alkyds advantages coat chemical

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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