Anti-UV waterborne nanocomposite coatings for exterior wood Anti-UV waterborne nanocomposite coatings for exterior wood 1 Université Laval 2 FPInnovations Mirela Vlad 1,2 prof. Bernard Riedl 1 dr. ing. Pierre Blanchet 2,1 2009 International Conference on Nanotechnology for the Forest Products Industry June 23-26, Edmonton, Alberta
21
Embed
Anti-UV waterborne nanocomposite coatings for exterior … · Anti-UV waterborne nanocomposite coatings for exterior ... World demand for Architectural Paints is forecast to ... Anti-UV
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Anti-UV waterborne nanocomposite coatings for exterior wood
Anti-UV waterborne nanocomposite coatings for exterior wood
1Université Laval2 FPInnovations
Mirela Vlad 1,2 prof. Bernard Riedl 1 dr. ing. Pierre Blanchet 2,1
2009 International Conference on Nanotechnology for the Forest Products Industry
June 23-26, Edmonton, Alberta
Wood Coatings Demand by Application & End Use (million dollars)
Year 1996 2001 2006 2011 2016
Global Wood Coatings Demand 1660 1958 2390 2790 3370
INTRODUCTION
Source: The Freedonia Group, Inc.
World demand for Architectural Paints is forecast to rise 3,9% per years through 2011 to a total of 21,5 million metric tons, valued at 47$ billion (US).
Water-based paints will expand their share of the global market to 73%.
0100
200300
400500
600700
800900
Siding Furniture Decking Flooring Windows &Doors
OtherApplications
19962001200620112016
Effects of UV on wooden substrates and wood coatings
Wooden substrates Wood coatings
Lignin degradation Embrittlement, cracking
Destruction of cell structure Yellowing of resins
Discoloration Loss of adhesion, delamination
Cracking Discoloration
Increase of water retention Loss of gloss, chalking
Decay attack Environmental etching
Photostabilization using nanosized UV absorbers
Zinc oxide (broad absorption spectrum from UVA to UVC)
Titanium oxide (absorption edge 350 nm)
Cerium oxide (broad absorption spectrum from UVA to UVC)
MOTIVATION
AGGREGATION TENDENCY OF NANOPARTICLEShigh specific surface area => high surface energySurface modification involve dispersants which stabilize the colloidal dispersion of nanoparticles.
A. Steric stabilization - this involves polymers added to the system adsorbing onto the particle surface and preventing the particle surfaces coming into close contact.
B. Electrostatic or charge stabilization - this is the effect on particle interaction due to the distribution of charged species in the system.
Factors affecting Zeta Potential:1. pH;2. Conductivity (particles with zeta potentials
> +30 mV or < -30 mV are considered stable);3. Concentration of a formulation component.
Waterborne nanocomposites
Pote
ntie
l (m
V)
Distance from particle surface
Zêta potentiel
Stern potentielSurface potentiel
0 mV
-100 mV
Slipping plan
Particle with negative surface
charge
Diffuse layer
Stern layer
PROBLEMATIC
MATERIALS
Exterior acrylic latex paint (SICO)
Nanoparticles of ZnO:Hydrophilic version (Degussa, 20 nm)Silanized version (Degussa-Evonik, 20 nm)
Nanoparticles of TiO2 :Uncoated (Sigma, 20 nm)Coated with Si and Al (Sachtleben, 10 nm)
Dispersants:Poly(acrylic acid) sodium salt PAA (M=2100 and 5000)Poly(methacrylic acid) PMAAPolyacrylamide PAM (M=17000)Copolymer of acrylic acid and sulfonated monomers