1. (Development and Trends of Waterborne Coatings)
水性塗料的發展與趨勢
(Development and Trends of Waterborne Coatings)
黃 義 欽
慶泰樹脂化學股份有限公司 總經理特助
勤 益 科 技 大 學 兼任教師
2011 年 04 月 29 日

2. Outline VOC Compliant Waterborne Coatings Waterborne Coating Systems
3. Film Formation Mechanism
4. Industrial Applications
5. Technology Trends of Waterborne PU Coatings

3. 1. VOC Compliant Waterborne
Coatings

4. Developing Waterborne Coatings
Background
Developing Waterborne Coatings
Solvent based Coatings
Safety
Environment
Health
Health Effect
Flammable Liquid
Air Pollution
Water Pollution
Water based Coatings
(1) Low V.O.C. content (2) Low risk of fire hazard
(3) Reducing worker exposure to solvent vapors

5. 1. VOCs (Volatile Organic Compounds) : < 250 g / L
2. VAHs (Volatile Aromatic Hydrocarbons) : < 0.04 %
3. Ingredients shall not contain :
3.1 Heavy metals : Cd, Pb, Cr(VI), Hg, As, Ba, Se, Sb
or their compounds
3.2 APEOs (Alkylphenylethoxylates)
3.3 Diethylene glycol methyl ether

6. 2. Waterborne Coating Systems

7. Nomenclature

8. Waterborne Coating Systems
Main Types
(Aqueous Emulsions)

9. Aqueous Solutions
Water Soluble

10. Primary Dispersions
Emulsion Polymerization

11. Secondary Dispersions

12. Secondary Dispersions
Aqueous Emulsions
Emulsion – An emulsion is a colloidal suspension of two immiscible liquids. Suspension of liquid droplets (dispersed phase) of certain size within a second immiscible liquid (continuous phase, water).
To prevent the mixture from separating, an ingredient, known as an emulsifier (surfactant) is added, which is attracted to both liquid droplets (dispersed phase) and a second immiscible liquid (continuous phase, water). One part of the emulsifier molecule (the polar end) is soluble in water and one part is soluble in the oil (the non-polar end).
Waterborne emulsion paints are called latex coatings.
Micelle
Polymer
Emulsifier
Polymer +
Water
External stabilization

13. Aqueous Emulsions

14. Aqueous Emulsions
Dispersion Process

15. Aqueous Emulsions
Dispersion Process

16. Secondary Dispersions
Water Reducible
Dispersion – A liquid dispersion is a system of dispersed particles suspended in a liquid without emulsifier. A resin dispersion uses a blend of solvents with low polarities that force the resin molecules into a mild clumping. Dispersions differ from emulsions in that the resin clumps (clusters) are small and do not require added emulsifiers to form a stable fluid mixture. Vigorous physical mixture alone is employed to form a dispersion.
COO- HR3N+
(1) Anionomer
Water or + A - N + H
(2) Cationomer
Internal stabilization

17. 3. Film Formation Mechanism

18. Minimum Film Formation Temperature
MFFT - The lowest temperature at which coalescence occurs
sufficiently to form a continuous polymer film
K = Tg
MFFT
( K = 0.80~0.98 )
Coalescing aids are used to assist in film forming
● Temporary plasticizers
● Low temperature film aid for paint applications
Polymer
Coalescing agent
Vol. Fraction of
Coalescent 1
MFFT Vs
KTgp
αTgP – TgS
KTgp TgS +

19. Requirements of Coalescing Aids
Compatibility
- An active solvent for the base polymer of the system.
Efficiency
- Amount of coalescing aid required to provide desired film
formation, properties
- Related to coalescing aids glass point (freezing point)
- In application testing for required performance
3. Low rate of evaporation
- An evaporation rate much lower than that of water
4. Low solubility in water
* Typical Coalescing aids : Ester alcohol , Glycol ether

20. Coalescing Effect Coalesced Uncoalesced The particles are soft enough,
they will fuse when the particles
collapses and form a film.
The particles are too hard, fusion will not occur and the coating will crack, flake, or pulverize.

21. Film Formation Mechanism
Particles get into close contact
And start to pack
Polymer particles deformation
Particles are deformed and packed
Film formation (Coalescing)
Polymer chains entangle and
particle boundaries disappear
Aqueous PU dispersions
(Solid Content: 30-50%)
Polymer inter-diffusion, leading to a
continue stable film
Stage I Evaporation of water
Stage II Particle deformation, T > MFFT
Stage III Coalescence
Stage IV Interdiffusion of polymer chains

22. Drying Mechanism Important parameters Compromise guidelines
It is important that the application, drying and coalescing conditions are controlled.
Important parameters
􀂇 Temperature
􀂇 Relative humidity
􀂇 Ventilation
Compromise guidelines
􀂇 Temperature : oC
􀂇 Relative humidity : %
􀂇 Ventilation
Sufficient to keep the relative humidity between 30 and 85 % close to the surface.
2. Better ventilation is required at a relative humidity in the range of %

23. Industrial Applications

24. Waterborne Polyurethane Systems
1 One Component Aqueous Polyurethanes
- Aqueous PU Dispersions
- Aqueous PU/Acrylic Hybrids
- Post Curing PU Dispersions
Two Component Aqueous Polyurethanes

25. Aqueous Polyurethane Dispersions

26. Aqueous Polyurethane Dispersions
Aqueous PU Ionomer
(1) Anionomer
(2) Cationomer A - N + H
COO- HR3N+
Prepolymer mixing
process
Ketimine / Ketazine
process
Acetone process
Internal stabilization
PU ionomer
Water

27. Aqueous PU/Acrylic Hybrids
Type 1
( Composites )
Type 3
( IPNS )
Type 2
( Core shell ) U A
(Interpenetrating Nets)
Benefits : To combine the advantages of both Acrylic & Urethane
Acrylic : (1) hardness (2) weatherability (3) pigmentability
Urethane : (1) toughness (2) flexibility (3) abrasion resistance

28. Post Curing of PU Dispersions
Ambient temperature curing
High temperature curing
Crosslinking Agents
High temperature curing
Ambient temperature curing
1. Melamine Formaldehyde
1. Polycarbodiimides
2. Blocked Polyisocyanate(aq.)
2. Polyazilidines
Improvements : (a) Hardness, (b) Adhesion, (c.)Blocking, (d) Abrasion,
(e) Water, Solvent & Chemical resistance.

29. Two Component Aqueous Polyurethanes
Reaction Paths of 2K Aqueous Polyurethanes
Water dispersible Polyols
Hydrophilic Polyisocyanates
Urethane
Carbamic acid
Urea

30. Aqueous Polyurethanes Industries Application
MARKETS
FUNCTIONS
SUBSTRASTES
Wood
Plastics
Metals
Papers
Leather
Textiles
Adhesives
Coatings
Finishes

31. Waterborne Epoxy System
Epoxy & Amine
Dispersed in Water
H2O Evaporates
Polymerize
Coating Applied
Epoxy & Amine
Dispersed in Water
H2O Evaporates
Polymerize
Coating Applied

32. Type I Waterborne Epoxies
Waterborne Epoxy System
Type I Waterborne Epoxies
Liquid
Epoxy
Water
Soluble
Amine -
Emulsion +
High
Shear
Amine acts as Epoxy Emulsifier
Water + Amine + Epoxy form Complex Emulsion
Emulsion Destabilizes Visible Pot Life
Liquid Epoxy Short Pot Life, Slow Dry

33. Type II Waterborne Epoxies
Waterborne Epoxy System
Type II Waterborne Epoxies
Epoxy Pre-dispersed with Nonionic Surfactant
Amine Migrates from Water into Epoxy
Polymerization Inside Particle Blind Pot Life
Solid Epoxy Long Pot Life, Fast Dry
Co-Solvents Needed for Coalescence

34. Waterborne Epoxy Systems
Industrial applications
Anticorrosive coatings for metal protection :
- Primer
- Intermediate
- Top coat
Coatings and floorings onto concrete :
- Wall paints
- Floor paints
- Mortars
- Self leveling floorings
- Epoxy cement concrete (ECC)
* Coatings on different substrates (plastics, glass, fibers, stone, …)

35. Coating Formulations Protection Polymers Colorants Water/Cosolvents
(Key Ingredient)
- Film formation
- Performance
- Adhesion
- Surface protection
- Special function
- Decoration / Color
Protection
Decoration
Water/Cosolvents
Additives
- Rheology control
- Solvation & Dilution
- Drying behavior
- Coalescing effect
- Defoaming
- Wetting / Dispersing
- Film protection
- Rheology control

36. 5. Technology Trends of Waterborne
Coatings

37. Technology Trends of Waterborne Coatings
Performance
Technology
Efficiency
Environment
Health
Safety

38. The End
Thank you for your attention