6th International Woodcoatings Congress
"Preserve, Protect, Prolong"
Mercure Hotel Amsterdam Aan de Amstel, The Netherlands
14-15 October 2008
Congress Programme
Tuesday 14 October 2008
8.15 - 9.05 Registration & Coffee
09.05 - 09.15 Welcome and Opening Remarks
Session 1: Introduction, Issues & Initiatives
Moderator: David Sykes, PRA, UK
09.05 - 12.45
1. Industrial Wood Coatings - Global Technology & Market Trends
Jonathan Bourne* & Jon Graystone
PRA, UK
To launch the conference, PRA will present an overview of the global
wood coatings market for both architectural and industrial sectors. A
review of technology trends indicated by the present and previous PRA wood
conferences will be given supported by an analysis of patent activity.
The key change drivers will be analysed to provide some insights into
current market trends and implications on future technology developments.
2. White Biotechnology for the Wood Coatings Industry
Dr. Stefan Friebel* & Claudia Philipp
Fraunhofer-WKI, Germany
In this study WKI has utilized 1,3-propandiol or long-chain dicarboxylic acid for
synthesis of coatings resins. These building blocks have been biotechnologically
converted from vegetable oil components. Utilizing 1,3-propandiol in the resin
synthesis the properties of the resulting polyurethane paints are investigated.
One major project issue is the substitution of 1,3-propandiol for 1,6-hexandiol with
the aim of a possible cost reduction. Another important item is the application of
1,18-octadecane dicarboxylic acid in paint resin synthesis. This long-chained
dicarboxylic acid is intended to serve the resin as an elasticity component.
The structure-property-relationship of the coatings resins has been examined.
A comparison of coating resins made of conventional building blocks will be presented
by means of hydrolysis stability, mechanical and physical properties.
3. REACH: Consequences for the Furniture Industry
Marie-Lise Roux
FCBA, France
After the implementation of European Directives (reduction of VOC emissions),
furniture companies must integrate now the impact of REACh. At first,
they must understand why they are concerned by this chemical regulation. Then, they
in the future, and, of course, what are the options to replace these substances or
preparations, as they must integrate new functionalities of the surface. Is REACh a
new opportunity or not to develop new coatings? The role of FCBA was to help furniture
SMEs to identify what will be the risk for the sector, to create links between all actors
of the supply chain including the distributors channels which stressed the furniture
manufacturers to be sure to answer to the customers in the future.
4. Process Integrated Paint Overspray Recycling for Wood Coatings
Dr Olaf Deppe*, Ulrich Hoffmann & Dr Sebastian Simon
Fraunhofer-WKI, Germany
Spray painting methods continue to determine the trend in the wood-processing industry although the overspray of 50-80% unavoidable with the process is the cause of costs and results in an increased burden on the environment. For this reason recycling methods for recovering overspray are becoming increasingly important. The available recycling methods sometimes considerably impair the quality of the recycled material, so that the recycled lacquer is often used for applications with lower quality requirements or disposed of as waste. In collaboration with relevant companies, the Fraunhofer institutes WKI and IPA have investigated the problems in paint recycling.
The aim of the project was to develop a recycling process which allowed lacquer to be recycled
without any impairment of the quality worth mentioning. Therefore the following studies had to
be carried out:
- Evidence of changes in surfaces made of recycling material
- Analysis of changes in the lacquer and the consequences arising from this
- Investigation of equipment-related influences on recycling
- Evidence of change in the composition of recycled lacquers
5. Moisture Protection of Wood Coatings Depending on Surface Hydrophobicity and Solid
Content
Dr Gerhard Grüll* & Michael Truskaller
Holzforschung, Austria
The moisture protection of wood coating systems is influenced by the total solid
content applied as well as by the hydrophobic properties of the coating film. Two
product categories were investigated, one to be used on longitudinal wood surfaces and
the other to seal the end grain of wood. Water permeability, water vapour permeability
and contact angle of water on the treated surfaces were measured. Water permeability
tests were also carried out with artificial mechanical defects of the surfaces. The
results showed that the influence of the total solid content applied was predominant
whereas the surface hydrophobicity was of minor importance. Systems with a higher total
solid content, however, showed a higher sensitivity to mechanical defects.
6. Specially Engineered Acrylic Hybrids: A New Technology Platform for Low VOC Decorative
Coatings
Dr Anne Koller
Rohm and Haas, France
Despite tightening VOC regulations, solvent based alkyds remain popular
in Europe due to certain key properties like extended open time, superb flow
and levelling and high potential gloss. They have deficiencies however such
as relatively poor durability, film yellowing and solvent odour as well as
an unfavourable environmental health and safety profile. Here we present an
alternative to solvent alkyds - a new technology platform featuring a
waterborne acrylic hybrid polymer dispersion suitable for use in low VOC
decorative coatings. This dispersion provided a much sought-after balance
of application and film properties. It delivers significant improvements in
open time, flow, re-brushing and repaint properties while maintaining the
desirable dry film properties of pure acrylic systems, notably little or no
yellowing. This new technology does not require the use of cobalt driers to
develop its dry film properties. The superior application properties are
achieved through the choice of the polymer design of the hybrid and an
alkyd like rheology. Its molecular structure leads to very good flow and
levelling and high gloss potential. The applied paint stays liquid for a
longer period of time and the coalescence is delayed thanks to its specific
design.
Session 2: New Technology for Exterior Wood Coatings
(This session runs in parallel to Session 3)
Tuesday 14 October, 14.00 - 17.30
Moderator: Jon Graystone, PRA, UK
7. New Acrylic Binder Technologies for Water-based Exterior Wood Coatings
Roland Baumstark* & Arno Tuchbreiter
BASF, Germany
Today modern water-based wood coatings have to meet the high market requirements,
such as perfect film formation and excellent blocking resistance through low coalescent
demand, and high elasticity at low temperatures for superior outdoor durability. Morphology
control of particles containing hard and soft polymer phases is one way to overcome these
contradictive product properties. To improve further application properties, such as
in can-clarity, blushing resistance and interaction with associative thickeners, the
dispersion's particle size has to be controlled and decreased to values below 50 nm at
low surfactant levels. Further improvements of properties can be achieved by replacing
the hard polymer phase by nano fine sized inorganic particles (e.g. silica), leading to
organic-inorganic hybrid materials. Such tailor made nanocomposite dispersions can be
produced via a special emulsion polymerization process based on silica sols and acrylic
monomers. The resulting nanocomposite films and formulated wood coating materials show
interesting blocking behaviour, enhanced water vapour permeability, excellent blushing
resistance and outstanding durability.
8. Functional UV Protective Wood Coating Systems
Dr Daniela Tesařová and Zdeněk Muzikář,
Mendel University, Czech Republic
The contribution investigates the issue of UV preservation new polymeric systems for the
protection against the solar irradiation. The polymeric systems that are determined for
wood coatings contain the UV absorbers bonded by covalent bonds in the macromolecules.
This study compares the influence of low molecular UV absorbers in wood coating systems with
polymeric systems containing UV absorbers bonded by covalent bonds in the macromolecules on the
physical-mechanical propertis of wood coatings. The influence of high molecular polymers with covalent
bonded UV absorber and low molecular UV absorbers missed in the wood coatings are tested during the
nature exposition outside, inside exposition after window glass and expositon in SUN Q-Test.
The influence of UV absorbers were tested on different kinds of wood such as walnut wood,
pine wood, spruce wood, pear wood, larch wood, lime wood, oak, beech, maple, ash, cherry wooda
and mahogany.
9. Powder Coating of Wood Plastic Composites
Dr Rico Emmler* & Detlef Kleber
Institute of Wood Technology Dresden, Germany
To obtain an acceptable service life and a decorative appearance, coatings is
necessary in many cases even for Wood-Plastics-Composites (WPC). One possibility
for effective surface protection is the application of powder coatings. For this
purpose, coating technologies have to be developed which provide high-quality surfaces, in particular
for use in outdoor conditions. The low polarity as well as the low surface tension of the
polyolefine matrix materials complicates surface coating considerably. A good wetting of the
surface and sufficient adhesion of the coating layers can be achieved by a pre-treatment of the
surfaces with flame or plasma in connection with the application of suitable primers.
Approaches for the application of powder coatings will be demonstrated on the basis of
laboratory and industrial coating experiements.
10. New Concepts for Light Stabilisation of Coloured Wood
Dr Christian Schaller*, Dr Daniel Rogez & Dr Wolfgang Peter
Ciba, Switzerland
Pale and light wood species show darkening and discoloration whereas colored wood
species show bleaching and decoloration under light exposure. Unfortunately there is no
universal light stabilization approach for all wood species. 2 years ago a new concept for
light stabilization of pale wood based on a combination of UV absorber (UVA), hindered amine
light stabilizer (HALS) and special lignin stabilizer was presented. In this paper the focus
is on light stabilization of colored or dark wood, like teak, mahogany, oak and cherry,
where the impact of mainly VIS light cause bleaching and decolorization. For these species a
new approach by combining selected VIS light screeners with UVA, showing excellent results in
color retention, is presented including methods how to predict optimal stabilization.
11. Development of a Method to Produce Grey Wooden Surfaces for Cladding and Decking
Dr Laurence Podgorski1*, Véronique Georges1, Izaskun Garmendia2 & Beatriz Sánchez Sarachu2
1FCBA, France
2Cidemco, Spain
Uncoated wood is commonly used in France for cladding and decking to minimise maintenance. However
wood surfaces progressively turn grey due to exposure to sunlight and water. This grey colour
develops after several months dependin g on the wood species and the exposure. Surfaces facing
South and West are most exposed and turn grey more rapidly than those facing North and East.
The result is unfortunate differences in the appearance of the building which obviously is not
appreciated by the end-users and which leads to a negative image of the wood material. As a
consequence of this some architects would like to have grey wood right from the beginning of the construction.
Producting grey wood using artificial weathering devices is possible but too expensive. In
this project the idea is to develop a non-film forming coating whose colour is similar to the grey
appearance produced by the natural weathering. This coating must be durable enough just to allow
a soft transition between its own degradation and the development of the grey colour produced
by the natural weathering.
12. Performance of Clear Coatings on Wood for Exterior Applications
Florian Tscherne*, Gerhard Gruell & Harald Bruckner
Holzforschung, Austria
Clear coatings on wood in exterior exposure are a challenge for formulation. New developments
of additives for UV- and light-protection lead to enhancement of the weathering properties of
the coating. For a long service-life the resistance of the coating against all weathering-factors have to be considered.
Clear coating-systems were exposed to natural and accelerated weathering. The coatings were
provided with different types of additives with light-protective an hydrophobic properties.
During the exposure the weather stability of the coatings and the change of colour and
contact-angle were studied. In addition the UV-transparency of free films and the liquid water
permeability and water-vapor-permeability of coated wooden panels were measured.
The tested clear coating systems showed very different performance in natural and artificial
weathering. Some coatings showed a very low resistance against weathering, some systems seem
to provide in the long run a very good performance.
Session 3: Compliant Technologies for Interior Wood Coatings
(This session runs in parallel to Session 2)
Tuesday 14 October, 14.00 - 17.30
Moderator: Peter Svane, Coating Consultancy, Denmark
13. Radical Innovations for the Formulation of UV-Coatings for Wood Floorings
Matthias Lokai*, M. Biehler, P. Enenkel & K. Menzel
BASF, Germany
The natural beauty and timeless elegance of wooden floors give them a special place
in modern interior design. To meet the high performance of factory prefinished floor tiles,
the surface of the wood is today coated with a high performance UV-coating.
Essential requirements for the parquet finishes are an excellent adhesion to the substrate,
a good abrasion resistance in consideration of the test method and a high scratch resistance.
This paper describes in the first part the latest developments in adhesion primers, performance
resins for abrasion resistance and improvements of the scratch resistance.
Besides these hard facts more and more soft facts are important for product differentiation.
The haptic and the optic of the surface get a higher importance for the buying decision of
consumers. A smooth surface and a very low gloss is trendy. With conventional matting agents it
is a great challenge. The authors show that matting with Excimer bulbs could be a promising
option.
14. The Consolidation of Powder Coatings on MDF Using High-Speed Scanning Lasers
Peter Kaczmar
TRADA Technology, UK
The paper outlines the results returned from a preliminary series of trials intended to
demonstrate the technical viability of consolidating powder coatings with high-speed scanning
lasers. The paper examines NdYAG and CO2 laser systems and explores the effects of moderating
laser scanning speed, power output and substrate moisture on coating morphology and thickness.
15. New Fast Drying Waterborne Two Pack Urethane Coatings for Industrial Wood Finishes
Dr Jaap Akkerman*, Dirk Mestach, Adriaan Sanderse, Richard Esser and Jan Goossen
Nuplex Resins, The Netherlands
Waterborne two component urethane coatings have been on the market for over a decade.
The acceptance of this technology has been slow initially, but with the legislation on the
emission of volatile organic components becoming ever stricter, paint formulators across
Europe are embracing these systems. One drawback that has slowed down the acceptance of
waterborne two component urethanes in industrial wood coatings has been the relatively slow
drying properties. For industrial wood coating lines where fast throughput is required and
coated objects must be handled, stacked or sanded shortly after application, existing
waterborne two component systems until now lacked performance.
In this paper a novel concept is discussed consisting of two waterborne polyols
with carefully controlled functionality and molecular weight distribution.
These polyols can be used either as such or in blends to fine-tune the balance between
aesthetical and chemical resistance properties versus drying speed and hardness build-up.
Several formulation parameters and their effect on coating performance, such as the choice
and ratio of isocyanate crosslinker to polyol are discussed and the use of the novel system
in industrial wood coatings is demonstrated.
16. New UV Powder Varnishes for Natural Wood and Derivatives
Francesc Williams*, J. Armengol & E. Grau
Cray Valley, Spain
Solvent paints and varnishes has been, traditionally, widely used on wood substrates.
But in recent days the regulations for VOC, especially the VOC European Directive, has
promoted the technological evolution of Industrial Wood Coatings. In this study we have
implemented some UV powder curing varnishes applied over natural wood, MDF or other wood
derivatives with good results. Additionally, as a remarkable result, the final cured coatings
have shown a good fire resistance according actual European regulations without the addition
of special additives.
17. Drying Technologies for Waterborne Coatings
Dr Christiane Swaboda*, Rico Emmler & Detlef Kleber
Institute of Wood Technology Dresden, Germany
One possibility for the VOC reduction during the application of wood coatings is the use of
waterborne coatings. Particularly during industrial furniture coatings, the use of effective accelerated
drying technologies is necessary to avoid high fibre swellings/sanding effort and long drying time before further
processing. Results of investigations on the surface quality and appearance of waterborne varnishes and
pigmented furniture coatings dried with 7 different technologies (i.e. IR, OIR, Microwave,
high-frequency, dry air, convection and combinations) are shown. Statments on the homogeneity
of the drying process of parts with complex geometries based on thermographic pictures are made.
Furthermore, an assessment of economic aspects based on necessary investments and measurements
of energy consumption during drying is demonstrated.
18. Novel Natural Wood Effect with UV Curable Powder Coatings
Ryan Schwarb
Keyland Polymer, USA
UV curable powder coatings provide durable finishes and offer unique design opportunities
in the powder coating of wood products. This paper presents a novel two step process to
create attractive natural wood and embossed finishes on MDF (medium density fiberboard).
The variety of wood finishes and design capability will be discussed as well as performance
properties of UV curable powder coatings.
Session 4: Exterior Wood Coatings - Test Method Development
(This session runs in parallel to Session 5)
Wednesday 15 October, 09.00 - 12.30
Moderator: Laurence Podgorski, FCBA, France
19. Effect of Surface Preparation on Service Life of Topcoats Applied to Weathered
Primer Paint
R. Sam Williams*, Mark Knaebe & Peter Sotos
Forest Products laboratory, USA
Top-coats should be applied to primer paint with two weeks. Unfortunately, it is not
always possible. For example, onset of winter weather shortly after applying primer may
delay top coat application until Spring. Scuff sanding or repriming are often
recommended remedial methods for preparing a weathered primer but there is little
research using modern paint formulations to support these practices. Wester redcedar boards having
a single coat of oil-alkyd or acrylic latex primer were placed outdoors for six months
(November 1995 to May 1996) at our exposure sites near Madison, Wisconsin and Gulfport, Mississippi.
After exposure, the weathered primers were prepared for top-coat application by 1), light
hand-sanding and washing without repriming, 2) repriming, or 3) no surface preparation. They
were finished with a single top-coat of acrylic latex or oil-alkyd paint and evaluated for
cracking, peeling, and mildew growth annually over 12 years. It was fund that light sanding
and washing withou repriming (1) had a deleterious effect. Top-coat performance was abut the same
for repriming (2) and no surface preparaton (3). Water-repellent preservative pretreatment of
western redcedar prior to priming did not improve service life of the finishes
20. New Methodologies to Measure the Weathering Effects on Exterior Wood Coatings
Davide Menotti*, Andrea Melchior, Daniele Bergamasco, Franco Bulian, Marilena Tolazzi &
Paolo Tirelli
University of Udine, Italy
Wood is an important raw material. However, compared with other materials, wood is subject to weather and biological degradation. To overcome these drawbacks wood is usually coated.
Moreover, a common experience is that these coatings are subject to the phenomena of degrading, which reduces performance.
To test the durability of coating materials for exterior work EN 927 3 and EN 927 6 standards are normally used. These standards have a critical point in the evaluation system, strongly dependent on the operator.
The aim of this research team is to develop new methodologies to test the performance of
wood coatings by means of objective tests and analysis. This study resumes some of the results
and the perspectives of this new approach.
21. Clear Varnishing Systems for Thermal Treated Non High Durable Wood Intended for
Exterior Use
Dr Rosa Perez*, Nuria Dominguez, Francisco Juan & Luis Millá
AIDIMA, Spain
This document shows the results and conclusions obtained in a research project dealing with
behaviour of wood coated with clear systems at outside. The wood species studied are thermal
treated with the proposal of analysing the influence of this treatment on the exterior
behaviour. Furthermore, the wood pieces are coated with different clear systems, solvent
and water-borne: oil, lasur and varnishes with the objective of researching the influence of
this treatment / coating combination.
Different ageing test methods are carried out on the test samples, assessing the results
(change of colour, change of gloss, cracking, whiteness, etc.). The discussion of the results
is intended to know the best solution to get a long life of the wood piece at outside.
22. Influence of Internal Stress and Extensibility on the Exterior Durability of Wood
Coatings
Dr Mari de Meijer* & Johan Nienhuis
Drywood Coatings, The Netherlands
Different types of coatings were characterised for: swelling by moisture,
moisture-permeability, elastic modulus and extensibility. These data were used to
calculate maximum internal stress. Internal stress was also measured directly whilst
changing temperature and humidity. The stress data were compared to cracking and
flaking results in both natural and accelerated weathering tests. Results showed that
high levels of stress occur if there is a difference in swelling between coating and wood.
In most cases stress relaxation took place rapidly. Comparing maximum stress, extensibility
and cracking, a good correlation between these data was found. The ratio between maximum
stress and extensibility appeared to be a very good predictor for crack formation.
23. Performance Classification of Coated Wooden Window Frames after Three Years Outdoor
Weathering as a Basis for Service Life Prediction
Imke de Windt*, I. Wuijtens, H. Coppens & J. Van Acker
Ghent University, Belgium
Accelerated weathering and specific test methods related e.g. to water absorption may
present problems when correlating results to actual performance outdoors. For accurate service
life prediction of exterior wooden joinery it is important to characterize performance in
worst case end use.
A test was set up with window frames consisting of nine different wood species and finished
with a range of industrial coatings. These were exposed vertically to natural weathering on
three different sites in Belgium (polder, city and Ardennes plateau). Visual assessments,
colour and gloss measurements were recorded each summer and winter for a period of three years.
Despite significant differences in the climatic conditions at the exposure sites, the
performance of the frames was found to be primarily determined by the wood species and the
coating resin type. Opaque systems perform better than semitransparent coatings while in
general waterborne alkyds have a better performance than acrylic coatings. The latter show
significant better performance when applied on e.g. moabi contrary to maritime pine.
24. Knot Staining after Artificial and Natural Ageing - Evaluation of Testing Methods
Ylva Karrfelt*, Dr Jan Ekstedt & Magdalena Sterley
SP Traetek, Sweden
The aim of this investigation was to determine the suitability of prEN 927-7 for testing
the ability of a coating system to inhibit knot staining. Eight coating systems were evaluated i
n this trial. Twenty replica of each system were tested with two accelerated, laboratory
exposures (QUV and Weather-o-Meter) and natural exposure.
The scope was to conclude if there exists any correlation between artificial and natural
exposure regarding knot staining. Correlation between different methods was determined.
The methods were also evaluated with respect to deviation of results and number of specimens
needed for determination of knot staining on coatings as a step of development of prEN 927-7.
Session 5: Novel Additives for Interior Wood Coatings
(This session runs in parallel to Session 4)
Wednesday 15 October, 09.00 - 12.30
Moderator: Peter Collins, PRA, UK
25. Improvement of Scratch Resistance of UV Cured Wood Coatings by Using Nano Alumina
Particles via Nano Indentation
P. Kardar1*, S. Bastani1 & M. Ebrahimi2
1Institute for Colorants, Paint & Coatings, Iran
2Amir Kabir University, Iran
In the recent years, the use of UV curable coatings has being considerably increased.
UV curable coatings are attractive because of their scratch and mar resistant characteristics,
rapid processing and the environmental friendliness of UV technology. Epoxy acrylate resins
are among the most famous UV curable systems which have been used in printing, electrical and
wood industries.
In this research, an epoxy acrylate resin was synthesized, and then the resin was formulated
with different multifunctional acrylate monomers and cured under UV radiation. To investigate
the effect of nano particles on some of physical and mechanical properties i.e. scratch and
gloss, of the UV cured resins, a suspension of nano alumina in tripropyleneglycoldiacrylate
(TPGDA), was included in the formulations. The scratch resistance was determined by pencil
hardness test and nano scratch tester (NST).The hardness of prepared films was evaluated by
using konig hardness tester and nano indenter.
The results showed that the visibility of scratch decreased when the nano particles were used.
It seems that the self-healing property of the films improved in the presence of nano particles.
erved that the optical properties (i.e. gloss, haze and transparency) of films with the nano
particles did not change.
26. Use of Nanoparticles in the Intumescence Process of Fire Protection Coatings
Dr Barbora Deppe* et al
Fraunhofer-WKI, Germany
Intumescent coatings are very effective in terms of protecting substrates in case of a fire. Intumescence
is defined as the swelling of substances when they are heated. By the impact of heat an energy-consuming reaction of the fire-proofing
coating forms a cm-thick insulating foam-layer on the surface to delay the critical temperatures as long as possible.
Because of some drawback of the coating properties, the commercial use is limited. Researchers
from industry and research institutes are cooperating to develop and optimise new high performance
fireproof cotings. One goal is to combine fire protective materials with ceramising fillers and
additives based on nanoparticles. Therefore, the involved companies cover the whole range of
material producers necessary for such coatings as well as end users and the participating R&D institutes provide
expertise in materials testing. Screening tests were performed to test the compatibility of
existing nano particle dispersions e.g. SiO2, alumina or TiO2 withthe general coating formulation. A water-based
fireproof coating formulation was used as a model system. Compared to a mirco particle TiO2, the viscosity is changed only
slightly when nano particle TiO2 is used. This offers the possibility of realising higher filling grades without a
negative influence on the rheology of the system. Fire tests showed a different development of the
foan formation when nano particles are used. The foam expands more and t is more stable too. The
fire protection performance is also positively influenced.
27. High Performance UV Cured Topcoats for Wood Application
Dr Nik Ghazali Nik Salleh*, Mohd Firdaus Yahya, H-J Gläsel, R Mehnert & Mohd Sofian Alias
Malaysian Nuclear Agency, Malaysia
In preparation of UV cured polymeric composites for interior wood applications, we
synthesized radiation curable silico-organic nanoparticles from silica/acrylates system.
These nano-sized silica particles were used as fillers. The surface of the silica was
chemically modified to improve the embedding of the filler within the acrylate matrix.
Modification of the silica surface using silane was done to overcome the problem of
incompatibility with acrylates at high silica contents. The nature of the nanoparticles
is now changed from hydrophilic to organophilic. Formulations useful for technical coating
processes can then be prepared. These composite materials showed highly improved mechanical
properties such as high resistant to scratch or abrasion. They also provide a high network
density whilst the coatings remain transparent. Another major driving force behind the
development of UV curing coatings over the last few decades is to cut or reduce the
emissions of volatile organic compounds (VOCs).
28. High Clarity Low Gloss Waterborne Lacquers for Wood
David J. Kent*, C. Tunice & C. Lindemeyer
Grace, Germany
Achieving low gloss levels in waterborne lacquers is no great problem using the silica
matting agents currently available. However, obtaining the required performance levels with
respect to other key properties can be problematic. Transparency of clear lacquers applied on
wood substrates is a more critical issue than in solvent borne systems. Due to the more
complex film-formation process, milkiness or haze may appear immediately after drying or
following exposure to extreme conditions of temperature and humidity in subsequent use.
This study reports on the impact of selected components on the transparency of applied
lacquer films matted with synthetic silica products and highlights those, including
organo-silane compounds which can provide significant improvements in clarity.
29. Controlled Polymerization - Highly Effective Dispersants for UV Coatings
Dr Stefan Mössmer
BYK Additives & Instruments, Germany
Modern, controlled polymerization processes like GTP (group transfer polymerization),
NMP (nitroxyl mediated polymerization) and RAFT (reversible addition fragmentation chain
transfer process) have found their way to be caried out on an industrial scale to manufacture
structured copolymers for a variety of application ranges. With these different controlled polymerization
processes it is possible - in contrast to state-of-the-art Free Radical Polymerisation - to
design special molecular architectures like block, gradient or comb like polymers. The specific
molecular structure has been found to have a direct influence on both pigment stabilization and
compatibility. The benefits of such Wetting and Dispersing Additives, made with controlled
polymerization technologies, are shown in comparison to conventional dispersants in High Solid UV
wood coatings as well as in waterborne UV Systems.
30. The Development of Methods to Evaluate Microfoam Generation in Waterborne Paints and the Role of Rheology.
Peter Svane
Coating Consultancy, Denmark
This paper presents results from a collaborative project on microfoam in paint films involving four
industrial cmpanies, Tego Chemie (DE), Teknos (DK) and Dyrup (DK) and two independent
laboratories, Roskilde University (DK) and Coating Consultancy (DK). The work has
the objectives of investigating A) the possible correlation between rheological properties of coatings and
their tendency to microfoam formation, B) whether sample orientation during flash-off and
drying affects the microfoam content of the film and C) how microfoam affects performance
during naturel exposure. In this presentation we focus on development of experimental techniques. The first
part will deal with rheological measurements (steady shear flow properties and structure formation by oscillatory techniques) aimed
at identifying which rheological properties are of relevance for microfoam formation and microfoam release before final
during of the film. The second part of the presentation will consider methods for the
assessment and quantification of microfoam in cured films on wood, particularly sample preparation and measurement
precision, by use of light and electron microscopy.
Session 6: New Systems for Wood Protection
Wednesday 15 October, 13.30 - 16.30
Moderator: Jonathan Bourne, PRA, UK
31. Inorganic Nanosols for Wood Functionalisation
Dr Boris Mahltig* & Horst Böttcher
GMBU, Germany
The treatment of wood with modified inorganic nanosols opens new opportunities to
functionalize and to protect wooden materials. According to the type of usage the sol
application can be performed by using different methods, from simple painting or spraying
up to the more expensive vacuum/pressure impregnation.
The usage of inorganic nanosols for the functionalization of wood should be demonstrated by
following applications:
- synthesis and modification of inorganic nanosols to improve the mechanical properties
of wood,
- application of modified silica sols to realise flame retardant, water repellent and
antimicrobial properties,
- application of nanosols for the protection of ThermoWood and for the restoring/preserving
of wooden cultural heritage.
32. Versatility of Solvent-free PUD for Coating Wood
Dr Rolf Gertzmann*, Dr M Almató & J.M. Garcia
Bayer MaterialScience, Germany
Emulsion polymers are solvent free coating materials and well known in the wood coating
industry. Even solvent free polyurethane dispersions (PUDs) have been available for decades.
However in most cases they have been used in other application areas than wood e.g.
textile coating. Because of tougher regulations just recently solvent free PUDs have been
brought to market especially designed for the wood coating industry. Eventually the final
property profile has been designed to meet different requirements for indoor and outdoor
applications, for furniture and parquet coatings etc. The ever increasing environmental
and economical aspects are met with the new systems. Examples for covering a broad
application spectrum with PUDs out of a tool box will be given.
33. Surface Characterisation of Pine and Heat Treated Spruce Modified with
Alkoxysilanes by Sol-Gel Process
Shaoxia Wang*, Saila Jämsä, Riitta Mahlberg, Juha Mannila, Juha Nikkola & Jouko Peltonen
Abo Akademi University, Finland
The surface morphology and chemical composition of pine and heat treated spruce modified
with alkoxysilanes by sol-gel process were characterized by Atomic Force Microscopy
(AFM), X-ray Photoelectron Spectroscopy (XPS) and Time of Flight Secondary Ion Mass
Spectroscopy (ToF-SIMS). Two types of alkoxysilanes differing in the organic component
were used as precursors in the sol-gel process and the coating effect of both materials
were investigated. The AFM results showed that one of the sol-gel coatings had a tendency
to smoothen the wood surfaces. XPS studies revealed that the chemical structure of wood
surfaces varied with two sol-gel coatings, as in O/C ratio and Si content. From the Si
ion distribution by ToF-SIMS images, it was concluded that both sol-gel coatings had been
successfully deposited onto the wood surfaces, forming thin coating layer following the
original wood fibre surfaces. The contact angle measurements also indicated that the water
repellent properties of both pine and heat treated spruce were improved to certain extents
by the sol-gel coatings. However, the water absorption tests showed that water uptake was
significantly diminished for sol-gel coated pine wood, whereas the relative low water
absorption values of heat treated spruce were not further affected by the sol-gel coatings.
34. UV/EB Coatings - VOC Compliant High Performance Solutions for Indoor and Outdoor Wood
Applications
Dr Xavier Deruyttere
Cytec Surface Specialties, Belgium
Stringent European regulations on chemicals and VOC together with the wish to improve the
lifetime, reduce the maintenance and keepthe nice aesthetics of wood are today still a
challenge for the furniture and joinery industry. In this paper we show how new high
performance water-based UV curable poyurethane dispersions can address all these requirments for
both indoor and outdoor spray and curtain wood coating applications. To this purpose suitable
designed novel structures now combine outstanding stain, chemical and scratch resistance with high reactivity in
both clear and pigmented systems, no need of co-solvents, low viscosity and in one case
also excellent weathering properties. Water-based radiation curable technology can be clearly
considered as the most promising solution in this changing landscapeof the Ruopean wood
coating market.
35. Sol-gel Modification of Wood Substrates to Retard Weathering
Mandla Tshabalala* and R Sam Williams
Forest Products Laboratory, USA
Wood specimens were treated with sol-gel systems based on metalorganic precursors of
silicon, iron, zirconium and titanium. The effect of these sol-gel systems on weathering
properties of wood was investigated. It was found that these sol-gel systems had positive
effect on the surface color stability and water vapor resistance of the specimens. Under
accelerated weathering conditions the sol-gel systems had an effect of retarding degradation
of the wood fiber. Scanning electron microscopy and energy dispersive x-ray analysis of the
specimens after accelerated weathering showed a marked difference in the pattern and
localization of degradation between the treated specimens and controls. While controls
showed severe micro-fracturing of the cell walls, the treated specimens showed no such
micro-fracturing.
* Indicates speaker where there is more than one author.
The organisers reserve the right to change papers and speakers if necessary.
