Overview: Aromatic Isocyanate 

Coating Applications 

Barbara Cummings 

Bayer MaterialScience

February 15, 2012
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Outline 

• Coatings Terminology “101”

• MDI/TDI-based Polymer Coatings: 

• Market Segments

• Crosslinking Technology, Application and Cure

• Basic 1K and 2K Reactions

• Application/End Uses

• Summary
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Coatings Terminology 101

• Isocyanate Monomer = A “monomer” is the starting unit from which the 

polymer is formed. A diisocyanate monomer consists of two isocyanate

groups.

• Polyisocyanate = A short chain oligomer made from a single monomer 

by directly linking the monomeric units. Also known as a homopolymer.

• Isocyanate-based Prepolymer = created by reacting monomeric 

isocyanates (diisocyanates) with diols or amines.

• Blocked isocyanate = Formed by the reaction of an isocyanate with a 

blocking agent, which when heated releases the blocking group and 

crosslinks with the polyol.

• Polyurethane Dispersion (PUD) = a fully reacted polyurethane 

dispersed in a medium, usually water.

• Uralkyd = urethane modified alkyd (oil based); fully reacted NCO

• Urethane Lacquer = solvent-borne resin (high MW); fully reacted NCO
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Coatings Terminology 101 (cont.)

• 1K = one component (e.g., PUDs, moisture cure)

• 2K = two component; common coreactants include: polyols (e.g., 

polyesters, polyethers) and polyamines

• Plural component spray = a spray coating system utilizing multiple 

components that are mixed upon application.

• Solvent-borne = coating with a solvent carrier

• Water-borne = coating with a water carrier

• 100% solids = coating without solvent/water carrier

• Moisture cure = coating cures using atmospheric moisture 

• E-coat = electrocoating (primers); electric current is used to deposit 

paint 

• OEM = original equipment manufacturer
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What do MDI/TDI-based Polymer Coatings 

offer and where are they used? 

• High durability

• Superior substrate 

adhesion

• Areas which “do not 

require” UV stability
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Market Segments 

Wood 

Industrial Maintenance/ 

Infrastructure

Military 

Agricultural/Construction/

Equipment (ACE)

Transportation

Transportation ACE

Military Industrial

Wood
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Crosslinking Technology, 

Application and Cure 
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Basic 2K Isocyanate Reactions 
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Basic 1K Moisture Cure Reaction 

R NH2 + R NCO

R N

H

C

N

O

R

H

R NCO + H2O R NH2

+ CO2
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MDI-based Polymer Coatings: Industrial (I), 

Contractor-Applied (CA), and Consumer(C)

*(C) = predominantly marketed via specialty shops or internet sales; some potential for direct consumer access
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TDI-based Polymer Coatings: Industrial (I), 

Contractor-Applied (CA), and Consumer(C)
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Uralkyd Chemistry 
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Urethane Modified Alkyd (Uralkyd)

• React glycerol, phthalic anhydride (PA) and fatty 

acid; hold out part of PA and substitute TDI

• Cures via autoxidation to form cross-linked coatings

• Used in wood floor/furniture coatings and industrial 

(metal) primers (inexpensive)

• Consumer use (i.e., wood “varnishes” and clearcoats)

• Fully reacted NCO (isocyanate)
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Polyurethane Dispersion Chemistry

Diisocyanates

Hydrophilic group

(ionic / non-ionic)

Diols:

Monomeric (e.g., hexanediol)

Polymeric (e.g., polyester)

Fatty Acid Based Polyols

O N

H

O

N O

H

O

H3C COON O

H

O

O N

H

O

O

n

O
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Polyurethane Dispersions (PUDs)

• Stable dispersion of high M.W. polyurethane-urea 

particles in water

• Film formed through coalescence of discrete particles

• Low solvent content or solvent free

• Ambient temperature or low bake drying

• Fully reacted NCO (isocyanate)
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Urethane Modified Lacquer Chemistry

Diisocyanates

Methyl Groups

Diols:

Monomeric (e.g., hexanediol)

Polymeric (e.g., polyester)

High M.W. Polyol

O N

H

O

N O

H

O

H3C COON O

H

O

O N

H

O

O

n

O

CH3
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Urethane Modified Lacquers 

• High molecular weight polyurethane (i.e., polyol

reacted with isocyanate) polymer dissolved in solvent 

• High VOC content (~30% solids)

• “Inexpensive” 

• Consumer market (e.g., clear, amber or colored 

varnish)

• Fully reacted NCO (isocyanate)
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Questions?