Silane Terminated Polyurethanes 2009-09-07

Silane TerminatedPolyurethanes

Edition: September 2009

Dr. Beate Baumbach • 2009-09-07 • Seite 2

Content

Comparison PUR and STP chemistry

� Crosslinking mechanism� Design of PUR polymers� Design of STP polymers� Properties of STPs

Synthetic routes to STPs

� Aminosilane route� NCO-silane Route� Comparison aminosilane route vs. NCO-silane route

Comparison STPs vs. MS-Polymers

� Chemical Differentiation� Advantages of STPs

Product range and formulation examples

� Product portfolio STPs� Formulation portfolio and application range� Formulation process


Comparison of PUR and STP ChemistryCrosslinking Mechanism

PURPUR STPSTP

+ H2O

NH2

NCO

OCN

+

N

H

NCO

=

H

- CO2

Si OCH3

OCH3

OCH3

+ H2O

SiCH3OCH3O

CH3O

Si O

OCH3

OCH3

CH3OSi

OCH3

- HOCH3


Comparison of PUR and STP ChemistryDesign of PUR Polymers

HO 4k-polyether OH 6k-polyether OH

OH

HO

NCOOCN

NCOOCN

NCOOCN

NCO

Polyurethane Polymers (moisture curing)

- CO2 + H2O

R-NCO + OCN-R

N-RH

R-NH

O

=


Comparison of PUR and STP ChemistryDesign of PUR Polymers

HO 4k-polyether OH 6k-polyether OH

OH

HO

NCOOCN

NCOOCN

NCOOCN

NCO

Polyurethane Polymers (moisture curing)

- CO2 + H2O

R-NCO + OCN-R

N-RH

R-NH

O

=

• PUR prepolymer approach allows to use low viscosity polymers

and to adjust final crosslinking density by the ratio of bi- and

trifunctional polyethers

• Soft elastic PUR prepolymers mainly build up linear molecular

weight !

• PUR prepolymer approach allows to use low viscosity polymers

and to adjust final crosslinking density by the ratio of bi- and

trifunctional polyethers

• Soft elastic PUR prepolymers mainly build up linear molecular

weight !


Comparison of PUR and STP ChemistryDesign of STP Polymers

= Si-O-Si Cluster

OMe

Si

OMe

OMeH2N

HO Acclaim Polyether OH NCOOCN

OMe

Si

OMe

OMe

MeO

Si

MeO

MeO

Silane-Terminated Polyurethane Polymers

SiCH3O

CH3OCH3OSi

OCH3

OCH3

OCH3 + SiOCH3

OOCH3

Si+ H2O

- HOCH3

CH3O

CH3O


Comparison of PUR and STP ChemistryDesign of STP Polymers

= Si-O-Si Cluster

OMe

Si

OMe

OMeH2N

HO Acclaim Polyether OH NCOOCN

OMe

Si

OMe

OMe

MeO

Si

MeO

MeO

Silane-Terminated Polyurethane Polymers

SiCH3O

CH3OCH3OSi

OCH3

OCH3

OCH3 + SiOCH3

OOCH3

Si+ H2O

- HOCH3

CH3O

CH3O

• STPs are multifunctional, they crosslink by curing and cannot

build up linear molecular weight

• Polymer chain length determines the distance between two

crosslinking points

• Therefore products for „soft“ applications have a high viscosity

• STPs are multifunctional, they crosslink by curing and cannot

build up linear molecular weight

• Polymer chain length determines the distance between two

crosslinking points

• Therefore products for „soft“ applications have a high viscosity


Comparison of PUR and STP ChemistryProperties of STPs

STPs combine positive properties of PUR …

� Tailored systems by use of PU building blocks

� Good cohesion

� Paintability

… and Silicones:

� Bubble free curing (even in thick layers)

� Good adhesion

� Free of isocyanates


Synthetic Routes to STPs Aminosilane Route

O HOH

R N C OO C N

N C OO C N

NH

N

R

S i

O

O M eO M e

O M e

NH

N

R

S i

O

M e OM e O

M e O

H R N S iO M e

O M eO M e

P o ly e th e r

P o ly u re th a n e

P o ly u re th a n e

• Broad molecularweight distribution

• Strong hydrogenbridges

• Broad molecularweight distribution

• Strong hydrogenbridges


Synthetic Routes to STPs NCO-silane Route

OHOH

O N

H

Si

O

OMeOMe

OMe

ON

H

Si

O

MeOMeO

MeO

SiOMe

OMeOMe

OCN

Polyether

Polyether

• Narrow molecularweight distribution

• Weak hydrogenbridges

• Narrow molecularweight distribution

• Weak hydrogenbridges


Synthetic Routes to STPs Comparison Aminosilane Route vs. NCO-silane Route

The two routes to STPs give different product properties:

a) Aminosilane route:

� Higher viscosity (dispersity / H-bridges)

� Higher modulus (H-bridges)

b) NCO-silane route:

� Lower viscosity

� Lower modulus


Comparison STPs vs. MS-PolymersChemical Differentiation

- Polyurethane backbone

- 3 reactive goups at each end

- Polyether backbone

- 2 reactive groups at each end

R = OCH3

R

R

R

R

R RPolyurethane Backbone SiSi

R

R

CH3

R

R

CH3

SiSi Polyether Backbone

Silane terminated Polyurethanes

Silane terminated Polyols (MS-Polymer)


Comparison STPs vs. MS-PolymersAdvantages of STPs

• Polyurethane backbone vs. polyether backbone�� Better mechanical properties

Higher elastic recovery / better creep resistance

• Trifunctional silanes vs. difunctional silanes�� Faster cure

Lower catalyst level neededUse of amine instead of tin catalyst possible !!!

• Polyurethane backbone + silicone endcapping�� Improved adhesion

• Big variety of building blocks and synthetic routs�� More freedom in polymer design & range of applications

Taylor-made products (molecular weight, functionality, type of PIC)Low and medium modulus range, sealants & adhesives


Product Range and Formulation ExamplesProduct Portfolio STPs

STP with low viscosity, for „hard" formulations with high modulus and low elongationapprox. 13approx. 5,000100%Desmoseal S XP 2749

STP with high viscosity, for „soft" formulations with low modulus and high elongationapprox. 2432,000 - 42,000100%Desmoseal S XP 2636

STP with high viscosity, for „hard“ formulations with high modulus and medium elongationapprox. 2030,000 - 40,00090 % in MesamollDesmoseal S XP 2458

Remarks

Molecular weight

[kg/mol]

Viscosity at 23 °C [mPas]

Delivery formProduct

Desmoseal S XP 2458 Desmoseal S XP 2636Desmoseal S XP 2749


Product Range and Formulation ExamplesFormulation Portfolio and Application Range

< 30 5040 7060Shore A

Construction Sealant

Technical Sealant

Elastic Adhesive

Structural Adhesive



< 30 5040 7060Shore A

Construction Sealant

Technical Sealant

Elastic Adhesive

Structural Adhesive

Desmoseal S XP 2458

→ Shore A 40 - A 80

- 1K SEA Sprayable- 1K ADH- 1K ADH Flooring- 1K ADH Transparent- 2K ADH

Desmoseal S XP 2749

→ Shore A 65 - 80

- 1K ADH- 1K ADH Flooring

Desmoseal S XP 2636

→ Shore A 20 - A 70

- 1K SEA- 1K SEA Sprayable- 1K ADH- 1K ADH Flooring- 1K ADH Transparent



Property range of sealants and elastic adhesives:

� Tensile strength 2.0 – 6.5 MPa

� Elongation at break 100 – 1,000 %

� Shore A 20 - 80

� Modulus@100% 0.3 – 3.0 MPa

STPs provide superior properties compared to difunctional hybrid polymers

STPs provide superior properties compared to difunctional hybrid polymers


Product Range and Formulation ExamplesFormulation Process

Polymer Formulation

Parquet Adhesive

Seam Sealer

Sealant

Elastic Adhesive

Application


Process 1: Physical pre-drying of fillers (preferred method)

• Use physically pre-dried fillers (e.g. 16 h at 100 °C)

• Add low amount of water scavanger to obtain storage stability

→ Low VOC content

Product Range and Formulation ExamplesGeneral Remarks Formulation Process

For the production of all formulations a double-walled vacuum dispenser with side scraper is recommended.

Process 2: Chemical drying of the formulation

• Use of fillers which are not pre-dried

• Add higher amount of water scavanger to obtain storage stability

→ High emissions of methanol possible


Step 1:

The vessel is filled with binder, plasticizer, additives (e.g. antioxidants), pigments and thixotropic agent . The filler is added under stirring in 2 - 3 portions. Catalyst and water scavenger are added together with the last one.

Then the premix is dispersed under stirring and cooling (temperature: < 60 °C) and static vacuum (< 200 mbar) for:

- 10 minutes at 3,000 rpm and- 10 minutes at 1,000 rpm

Finally the water content of the premix should be < 200 ppm.

Product Range and Formulation ExamplesFormulation Process for 1 kg Batches


Step 2:

The adhesion promotors (e.g. amino silanes) are added to the premix under stirring and cooling (temperature: < 60 °C) for:

-10 minutes under static vacuum (< 200 mbar) at 1,000 rpm and- 5 minutes under dynamic vacuum at 1,000 rpm

The final mixture is filled into plastic cartridges or inside coated aluminium cartridges.

Product Range and Formulation ExamplesFormulation Process for 1 kg Batches


Important points:

• A temperature of 70°C should not be exceeded, othe rwise a negativeimpact on the final properties can be noticed

• The amount of water is crucial for the storage stability of theformulation

• The water scavanger (e.g. vinyltrimethoxysilane) has a low boilingpoint and might evaporate during the process

→ Use of vacuum needs to be controlled

Product Range and Formulation ExamplesGeneral Remarks Formulation Process


Mechanical properties:• Polymer• Plasticiser• Filler• Aminosilanes

Viscosity / Rheology:• Thixotropic agent• Plasticiser• Filler• Solvents

Adhesion properties:• Aminosilanes• Plasticiser• Amount of catalyst• Light stabilisers

Storage stability:• Moisture content• Amount of water scavanger• Aminosilanes

Product Range and Formulation ExamplesSummary Formulation Process


Thank you for your attention

Documents

Silane Terminated Polyurethanes 2009-09-07