new insights into the aqueous phase of 2k pur formulations

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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