New insights into the aqueous phase of

2K PUR formulations via DGU measurements

Frédéric LUCAS, Jules MIKHAEL, Ulrich TROMSDORF

Wood

Industrial

Automotive

2K PUR

Coatings

Crosslinker

Dispersion

Introduction

2

2K-PUR Formulation:

Applications:

Cross-linker

Polyisocyanate

Binder Polyol

Solvent &

Additives

Coating

NCO

NCO

OCN

OH OH OH OH+ +

NH-C-O

O

NCO + HO

Urethane

IndustrialAutomotive Plastic

IndustrialAutomotive Plastic

Introduction

3

2K-PUR Formulation :

Applications :

Cross-linker

Polyisocyanate

Binder Polyol

Solvent &

Additives

Coating

NCO

NCO

OCN

OH OH OH OH+ +

NH-C-O

O

NCO + HO

Urethane

HDI-Based trimer

(Isocyanurate)

NCO

N

N

N(CH

2)6

(CH2)6

O

OO

NCO

(CH2)6

OCN

2K-PUR Formulation:

Applications:

Introduction

4

Cross-linker

Water-dispersible

Polyisocyanate

Coating

+ +

NH-C-O

O

NCO + HO

Urethane

NCOOCN

BinderPolyacrylate / Polyurethane

OH Dispersion

ACE ComponentsTransportationWood Coatings

5

NCO

NCO

OCN

H Hydrophile

NCO

NCO

OCN NCOOCN

+

NH-CO Hydrophile

Hydrophile acts as :

- a surfactant

- a protecting layer

Dispersible via mechanical or hand mixing

„Pot-life“ of several hours

Chemistry Dispersibilty Aqueous system

Technical solution: Polyisocyanate modification with a reactive hydrophile

H2OH2O

H2O

H2O

H2OH2O

H2O

H2O

Water-dispersible PolyisocyanatesSynthetic Route

6

Waterborne PUR

Formulations

Handling in waterborne 2K Polyurethane Technology

OH Dispersion

Water-emulsifiable

Polyisocyanate (PIC)

Addition of PIC

in the dispersion(pure or diluted)

?Formulation

Storage

Application

Coating

One question among others…

Study of the aqueous phase required

+

Separate Droplets Grafted Droplets Merged Droplets

Question: What is the nature of the aqueous phase after mixing ?

7

Film FormationPot-life

Density Gradient Ultra-centrifugation

Principle

RadiusCentr. field

RotorAxe Detector

Analytical Ultra-centrifuge:• Up to 60.000 rpm • Up to 300.000 g

8

8

Density Gradient Ultra-centrifugation

The perfect tool

Density Gradient

de

nsi

ty

H2O sugar

1

2

cell radius

0,85 0,90 0,95 1,00 1,05 1,10 1,15 1,20 1,25 1,30 1,35

0

2

4

6

8

10

12

14

16

6H2O- 4Meth / 0,15 NY

6H2O- 4Meth / 0,10 NY

5H2O- 5Meth / 0,10 NY

2H2O- 8Meth / 0,15 NY

2H2O- 8Meth / 0,10 NY

4H2O- 6Meth / 0,10 NY

H2O / 0,06 NY

H2O / 0,08 NY

H2O / 0,10 NY

H2O / 0,12 NY

H2O / 0,15 NY

H2O / 0,20 NY

H2O / 0,25 NY

Gra

die

nt

Dichte [g/cm³]

D2O / 0,25 NY

Gradient Ranges with Nycodenz after 22h

Separation by density - and not by particle size or particle morphology

The density difference between the polyisocyanates (1,20 g/cm3) and the dispersion

(1,11-1,17 g/cm3) is large enough to perform DGU measurements

9

Proof of Concept

First formulation: Easy peasy!

10

Polyisocyanate

1,12 1,14 1,16 1,18 1,20 1,22SINGLE

COMPONENTS

FORMULATION

OH Dispersion A

1,12 1,14 1,16 1,18 1,20 1,22

1,12 1,14 1,16 1,18 1,20 1,22

Density (g/cm3)

11

Polyisocyanate

1,12 1,14 1,16 1,18 1,20 1,22SINGLE

COMPONENTS

FORMULATION

OH Dispersion B

1,12 1,14 1,16 1,18 1,20 1,22

1,12 1,14 1,16 1,18 1,20 1,22

Density (g/cm3)

Proof of Concept

The tree that hides the forest

12

Polyisocyanate

1,12 1,14 1,16 1,18 1,20 1,22SINGLE

COMPONENTS

FORMULATION

OH Dispersion B

1,12 1,14 1,16 1,18 1,20 1,22

1,12 1,14 1,16 1,18 1,20 1,22

?

Density (g/cm3)

Proof of Concept

The tree that hides the forest

13

Polyisocyanate

1,12 1,14 1,16 1,18 1,20 1,22SINGLE

COMPONENTS

FORMULATION

OH Dispersion B

1,12 1,14 1,16 1,18 1,20 1,22

1,12 1,14 1,16 1,18 1,20 1,22

?

TEM Imaging

with EDX (N atom):

Density (g/cm3)

Proof of Concept

Grafting does occur

14

Results from feasibility study:

Next steps: Elucidate factors influencing grafting

• Dispersion: Presence of “water-solubles”, functionality

• Polyisocyanate: Steric vs Anionic stabilization

• Formulation: Index

2 Dispersions – 2 Situations

Why?

-OHHO--OHHO-

OH Dispersion A OH Dispersion B

Large particlesEmulsifer as surfactants

Primary OHLow Index

= SEPARATE DROPLETS

Small particles Polymer as surfactant

OH + other functional groupHigh Index

=GRAFTED DROPLETS

15

Polyisocyanate

1,12 1,14 1,16 1,18 1,20 1,22SINGLE

COMPONENTS

FORMULATION

OH Dispersion

OH Dispersion + „water-solubles“

Density (g/cm3)

Influence of the OH Dispersion

Presence of „water-solubles“

Presence of

„water-solubles“ =

GRAFTING

16

Polyisocyanate

1,12 1,14 1,16 1,18 1,20 1,22SINGLE

COMPONENTS

FORMULATION

OH Dispersion

OH Dispersion + funct. groups

Introduction of funct.

groups = GRAFTING

Density (g/cm3)

Influence of the OH Dispersion

Presence of functional groups

17

Polyisocyanatesteric 1,12 1,14 1,16 1,18 1,20 1,22

FORMULATION

Dispersion

Ionic hydrophile =

GRAFTING

Polyisocyanateionic

SINGLE COMPONENTS

Density (g/cm3)

Influence of the Polyisocyanate

Steric vs Ionic Hydrophile

Influence of the Formulation

Index

SINGLE COMPONENTS

FORMULATION

Index 40

Index 100

OH Dispersion B

Higher Index =

more GRAFTING

Polyisocyanatesteric 1,12 1,14 1,16 1,18 1,20 1,22

Density (g/cm3)

Results

Snap-shot

Summary:

- No “water-solubles”

- Primary OH funct.

- Polyisocyanate steric

- Low Index

- “water-solubles”

- Funct. Groups

- Polyisocyanate ionic

- High Index

OH Dispersion

Water-dispersible

Polyisocyanate+-OHHO-

Separate

Particles

Grafted

Particles

-OHHO-

Pot-life measurements: Study using commercial products

Trends observed during DGU study validated in practical situations

Degree of grafting correlates with the pot-life… generally !

Deviations exist: Influence of additional factors (mixing, co-solvent, type of

polyisocyanate, polarity…)

Dispersion 1 Dispersion 2 Dispersion 3 Dispersion 4

Funct. groups No Yes Yes Yes

„Water-solubles“ No Yes Yes No

Hydrophilic Steric Ionic Steric Steric

Degree of grafting 0% < 5% > 30% 20%

Pot-Life > 6 hours App. 4 hours < 2 hours App. 5 hours

Fine but…

Can we use these results ?

2130.03.2017 CONFIDENTIAL - Dr. A.Panchenko, CI/BA

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