Momentive Silylated Polyurethanes for Pressure Sensitive Adhesive Applications (05-Oct-2009)

Silylated Polyurethanes for
Pressure Sensitive Adhesive Applications

Roy M. Griswold Albany, NY

Outline

PSA Definition

Intuitive Overview of Adhesion

Anatomy of Tack and Peel Adhesion

Fundamental Forces of Adhesion vs. Practical Adhesion

SPUR^+* PSA Adhesive Properties

Chemical Resistance

Conclusions

References

*SPUR and SPUR+ are trademarks of Momentive Performance Materials Inc.

Copyright 2009 Momentive Performance Materials Inc. All rights reserved.

2

Pressure Sensitive Adhesives

Definition of a PSA

Aggressive and permanent tack under low pressure
Required adhesion and cohesive strength sufficient for clean removal Sufficient shear (creep) resistance under load

Standard Tests

Tack, Peel Adhesion and Shear (Creep) Resistance

Classes of PSAs:

Rubber: Low cost, formulated adhesives (plasticizer(s), resin tackifiers)

Acrylic: Low-to-high cost, monomers control performance

Silicone: High cost, formulated-resin(s) and process

SPUR^+* PSAs : High cost, polyols/silane control performance, can be tackified Uniqueness based on hard-soft segments and silane crosslinking

*SPUR and SPUR+ are trademarks of Momentive Performance Materials Inc.

Copyright 2009 Momentive Performance Materials Inc. All rights reserved.

3

Adhesion- Intuitive Overview

Adhesive at Interface to Adherend

A

B

^BB B B

A

B B

B B

B

B

B B

Adhesive in Bulk Phase

Bulk Adhesive Cross Section

Surface-Bulk and Surface-Adherend Adhesion Factors

Van der Waals
Acid-Base
Dipole-Dipole
Surface energies
Surface Treatment-silanes, titanates Interfacial Diffusion
Mechanical Interlocking-Adherend roughness Mw, Mc, Me of adhesive
Contaminants

Copyright 2009 Momentive Performance Materials Inc. All rights reserved.

4

Anatomy of Tack

                               A. Zosel,
"Molecular Structure, Mecahnical Behaviour and Adhesion Performance of Pressure Sensitve Adhesives"

Tack is a Viscoelastic Property with Rate and Temperature dependence G', Me, Mc, Polydispersity

Copyright 2009 Momentive Performance Materials Inc. All rights reserved.

Dahlquist Criteria

5

Anatomy of Peel Adhesion

Kaelble-Dahlquist Analysis

Based on Linear Elastic Fracture Mechanics corrected for Bending of Beams Analysis

Damped Wave Function dependent on Force, Area, Peel Angle, Adhesive-Adherend Physical Constants

Copyright 2009 Momentive Performance Materials Inc. All rights reserved.

6

Fundamental Forces of Adhesion and Practical Adhesion

W_B = G₀ (1 + (ra_T)^z)

W_B is work to break

G₀ is the intrinsic adhesion energy (peel f...