Final Report Summary - WOODLIFE (Extended service-life and improved properties of wood products through the use of functional nanoparticles in clear coating and adhesive systems)
Executive Summary:
The long term objective of the WOODLIFE project was to provide coated and glued wood products with substantially improved durability for a more sustainable society. The project aimed to develop new water-based clear coating systems for wood with improved UV-absorbing properties, and to develop new water-based thermoplastic wood adhesives with improved mechanical properties. The new coating and adhesive systems were designed through molecular manufacturing of inorganic nanoparticles, nanoclays and composite organic-inorganic binders with predictable and controllable properties.
In the case of wood adhesives we have focused on PVAc adhesives for load bearing glulam beams. Within the WOODLIFE project we have developed systems which pass the critical heat test WATT 91. One system contains physical blends of surface engineered colloidal silica mixed with PVAc. Another system is a hybrid binder with hydrophobic colloidal silica encapsulated in PVAc. Furthermore we have encapsulated nanoclay with comonomer and PVAc which show improved heat and wet resistance.
In the case of exterior clear coatings on wood we have focused on wood panels and window frames. Within the WOODLIFE project we have developed systems which approach the 440 nm limit but still are transparent. Nanoparticles of cerium oxide, iron-doped cerium oxide and zink oxide have been directly incorporated in waterborne clear coating formulations showing promsing performance in field tests. Furthermore nanoparticles of the same materials have been encapsulated into acrylic latex binders and these composite binders show also promising results in field tests.
Sustainability assessments show potential cost benefits and environmental benefits of using wooden windows frames painted with WOODLIFE paint. Sustainability assessments of wooden glulam beams show potential environmental benefits of using WOODLIFE adhesive.
Two patent applications have been submitted as a result of the WOODLIFE project. One patent application made by Energenics covering their ceria and iron-doped ceria development for UV absorption. The patent application number is WO2012117238A1. One joint patent application by UPV/EHU, Akzo Nobel, BYK, Energenics and YKI (SP) covering their development of encapsulated hybrid binders for adhesive and clear coating applications. The patent application number is PCT/EP 2013/060095.
Project Context and Objectives:
Main objectives
The long term objective of the WOODLIFE project was to provide coated and glued wood products with substantially improved durability for a more sustainable society. The project aimed to develop new water-based clear coating systems for wood with improved UV-absorbing properties, and to develop new water-based thermoplastic wood adhesives with improved mechanical properties. The new coating and adhesive systems were designed through molecular manufacturing of inorganic nanoparticles, nanoclays and composite organic-inorganic binders with predictable and controllable properties. The objectives were achieved by:
- Development of metal oxide nanoparticles by molecular manufacturing that have an absorption in the range 250 - 440 nm and that are well-dispersed in water-based clear coating formulation, and thus give a transparent coating film in the visible part of the UV-VIS spectrum.
- Development of metal oxide nanoparticles by molecular manufacturing that have an absorption in the range 250 - 440 nm and that are suitable to incorporate in polymeric binders for clear coating application in order to get a well-dispersed system, and thus give a transparent coating film in the visible part of the UV-VIS spectrum.
- Surface modification of nanoclays and nanosilica particles in order to incorporate them in a water-based adhesive or in the binder particles of a water-based adhesive.
- Development of composite binders containing well-dispersed metal oxide nanoparticles for water-based clear coating applications.
- Development of composite binders containing well-dispersed nanoclay particles or nanosilica particles for water-based adhesive applications.
- Formulation of clear coating systems and adhesive systems with suitable wet state properties (rheology and wetting of wood for example) and dry state properties (film formation and adhesion to wood for example).
- Production of a water-based clear coat prototype with the following properties:
UV-absorption 250 - 440 nm, high transparency, 2-5 times longer service-life of coated wood panels compared to the reference systems used today (field tests after 2 years show promising results, however longer field tests were not possible in this 3-year project). Production of a water-based wood adhesive prototype with the following properties: low cold creep of corresponding wood joints, temperature resistance of corresponding wood joints, low formaldehyde content.
Background
Wood has an intrinsic potential to fulfill the criteria for being a competitive and sustainable engineering material, i.e. a renewable resource available in vast quantities and formed as a natural composite with an extraordinary high strength-to-weight ratio. For outdoor use it is, however, necessary to enhance the performance and long-term durability of wood-based materials.
One particular problematic area and drawback for the use of wood as an engineering material outdoor, is its high sensitivity for UV degradation. It is common knowledge that wood is affected by light, both by color changes and by degradation of the surface. Particularly during outdoor exposure, the effects are rapidly noticeable on untreated wood, which becomes grey and more loosely bound raised fibers become visible at the surface. This is mainly because the surface lignin (which represents about 30 % of the wood weight) is degraded into smaller molecular fragments that can be washed out by rain.
Traditionally, UV protection of wood has been performed through hiding the sensitive lignin under pigments, through applying a tinted wood coating, which efficiently hinders the UV light to reach the lignin. To date, this method has been widely accepted in the Scandinavian and North American countries, but is not fully accepted in other countries, e.g. in southern Europe and Japan. Moreover, a recent trend within architecture is to include clear-coated wood as a significant part of the exterior design, thereby taking advantage of the appealing aesthetic properties of the wood material.
Furthermore, it is also important to develop new improved clear coating systems from a legal point of view. In some European countries, for example in Germany, there is a need for a warranty from the coating companies that the coating will last for a certain period (for example 5 or 10 years). With improved clear coatings it will be easier for the coating companies to give these warranties.
To protect wood products effectively during weathering, the high energetic portion of the sunlight spectrum, UV-VIS (250-440 nm), should be cut off or filtered before it reaches the wood surface. Due to tighter regulations and environmental concerns in the coating sectors, water-borne clear coatings are more appreciated compared to the solvent-based ones. Traditionally, organic UV absorbers are used in clear coatings for wood applications, however these substances tend to degrade upon outdoor weathering. As a result of this, the coating not only loses its intended UV-protection function very quickly, but it also contributes to volatile organic compounds (VOCs) emission to the environment. Current clear coating systems with organic UV absorbers need to be replaced or repainted after approximately 2 years. Thus, if superior UV-absorbing systems can be identified for water-based clear coatings the service-life of the wood could be extended and the environmental impact and the cost for maintenance and for wood replacement will be decreased.
Functional engineered nanoparticles can also be introduced into water-based wood adhesives in order to improve the properties of wood-adhesive joints. The most commonly used adhesives in wood applications are the thermoset formaldehyde-based adhesives (urea-formaldehyde UF, melamine-formaldehyde MF, phenyl-formaldehyde PF, resorcinol-formaldehyde RF). New adhesive systems with very low formaldehyde emission have been developed during the last years. The formaldehyde released from an adhesive joint using these new systems is very low, even lower than the formaldehyde released from the wood material itself. Thus, the formaldehyde emission from these adhesive systems is not a major concern today. However, if the mechanical properties of water-based low formaldehyde adhesives, and of other water-based thermoplastic adhesive (such as polyvinyl acetate, PVAc), can be improved it would be possible to use the wood products based on these systems for a longer time, leading to a more sustainable society. Moreover, it would be possible to use PVAc adhesives instead of the more expensive MUF/PRF adhesives in some load-bearing applications such as glulam beams.
Incorporation of nanoparticles in water-based adhesives can increase the cohesive strength of the adhesive without decreasing the adhesive properties of the adhesive. However, it is crucial that the nanoparticles are well dispersed in the polymer matrix and that the nanoparticles are compatible with the adhesive polymer. The price of the nanoparticles used in this application should not be too high, therefore it is suitable to work with different types of clays, for example exfoliated nanoclays, and silica nanoparticles.
WOODLIFE Concept
In the WOODLIFE project we have developed new water-based clear coating systems and new water-based adhesive systems for wood applications through the molecular manufacturing of inorganic nanoparticles, nanoclays and composite organic inorganic binders.
Inorganic nanoparticles with controlled morphology, size and crystallinity can be developed by molecular manufacturing and they are a new type of nano building blocks for sub-micro, micro and macro scale engineering. For example, it is possible to synthesize and create a beautiful three-dimentional nanostructure from these inorganic building blocks by controlled self-assembly technology. Molecular manufacturing of semiconducting nanoparticles allows us to control the materials properties at an atomic level, to create a novel material with the desired optical and mechanical property. For example, UV-absorbing semiconducting metal oxide nanoparticles with a tailored band-gap can be created by applying basic principles of the molecular factory, so that the UV-absorbance of the materials can be tuned to the desired wavelength, while keeping high transparency in the visible region. Fine tuning of particle size of semiconducting nanoparticles and their interaction with the target polymer matrix is again a matter of molecular manufacturing. It is highly important to select both inorganic precursors, stabilizers, monomers and polymer at the atomic level so that the nanoparticles with the right band-gap and right surface functionality can be created. The principle of the molecular factory is critical to engineer materials at nanoscale and to tailor the surface properties of the particles at the molecular level.
The dispersibility of inorganic nanoparticles can be greatly improved by tailoring the surface chemistry of particles at the molecular level. This was in the project achieved by synthesis of nanoparticles in the presence of water-soluble organic molecules and surfactants. The dispersibility of the nanoparticles in the coating or adhesive system was also improved by incorporation of nanoparticles in minimemulsion droplets followed by polymerization creating composite binder particles. The manufacture of the composite binders was in some examples performed with inorganic nanoparticles and nanoclay particles which were surface modified to have reactive sites present at the surface. The polymerization was then initiated from the reactive sites of the nanoparticles and the nanoparticles were covalently attached to the polymer matrix.
The final clear coating or adhesive film is an inorganic-organic composite film with structures over multiple length scales; the nanoparticles in the range 2-20 nm, the binder particles in the range 100-200 nm and the final film in the range 10-200 μm. The specific structure of the film influences the properties such as UV-absorption, transparency and mechanical properties.
Project Results:
WP1 Development of metal oxide nanoparticle dispersions
Tasks:
1.1 Enhanced understanding of nanoparticle development
The beneficiaries in WP1 (YKI, SIRRIS, Energenics, Eka, BYK) have performed a literature, market and patent search and summarized the results in Deliverable D1.1 “Literature, patent and market survey for development of metal oxide nanoparticles”.
1.2 Synthesis of UV-absorbing nanoparticle dispersions for direct incorporation in water based clear coats – Liquid phase methods
Both water borne and solvent borne dispersions of CeO2 with high colloidal stability, and solid content, have been successfully developed by both YKI (SP) and Energenics independently through liquid phase methods for UV screening application in the clear coats and samples have been delivered to the relevant work packages for further formulations and testing.
Both water borne and solvent borne dispersions of Fe-doped CeO2 have been developed by Energenics through liquid phase methods for UV screening application in the clear coats. Compared to pure ceria this Fe-doped CeO2 nanoparticle provides extended absorption in the UV region.
1.3 Synthesis of UV-absorbing nanoparticle dispersions for direct incorporation in water based clear coats – Plasma methods
Nanopowders of ZnO and Ce-doped ZnO have been successfully synthesized by Sirris. Although as prepared samples are aggregated, crystallite size of 29-78nm has been calculated from XRD. These powders have been deagglomerated and stabilized by BYK and delivered to SP for UV-VIS study. The results from task 1.3 have been reported in Deliverable D1.4 “Development of UV absorbing metal oxide nanoparticles for clear coatings – For direct incorporation”.
1.4 Synthesis of UV-absorbing nanoparticle dispersions for incorporation in hybrid binders for clear coats – Liquid phase methods
YKI (SP) and Energenics have both worked on the development of suitable liquid phase methods for synthesis of UV-absorbing nanoparticles that can be incorporated directly in hybrid binders for clear coatings.
The methods were then used to produce metal oxide nanoparticle dispersion in organic solvent with optimal UV-absorbing properties and with maximal transparency in the visible range. Mainly CeO2 and modified CeO2 samples have been produced and they have been surface modified to be compatible with the monomers of the binders to be developed in WP3. Band gap engineering has been initiated and preliminary results show an extended UV-absorption towards 440 nm. The results from task 1.4 have been reported in Deliverable D1.3 “Development of UV absorbing metal oxide nanoparticles for clear coatings – For hybrid binders”.
1.5 Development of silica nanoparticles for incorporation in adhesive systems
This task was prolonged to month 24. Colloidal silica samples have been developed at Eka. They have evaluated a number of different colloidal silica samples for adhesive formulations with PVAc (polyvinyl acetate). Both commercial samples have been selected and new silica samples have been synthesized with a more hydrophobic functionality. The most optimized silicas show very interesting properties when mixed with PVAc from Casco. The results from Task 1.5 have been reported in Deliverable D1.2 “Development of surface engineered silica nanoparticles for adhesives”.
1.6 Cost estimation for nanoparticle production
The cost estimation has been conducted according to plan and is reported in Deliverable 1.5 “Cost estimation of metal oxide nanoparticle production”.
1.7 Technical project management WP1
The technical project management has been realized through email correspondence, phone meetings and reviewing the risk log of the project. There has been one work plan change in WP1; Task 1.5 was extended to month 24 in order to increase the chances of improving adhesive properties with colloidal silica, which also was obtained.
WP2 Development of nanoclay particle dispersions
Tasks:
2.1 Enhanced understanding of nanoclay particle development
The partners in WP2 (YKI, UPV/EHU, Laviosa) have performed a literature, market and patent search and summarized the results in Deliverable D 2.1 “Literature, patent and market survey for surface modification of nanoclays”.
2.2 Preparation and dispersion of nanoclays, for direct incorporation in water-based adhesives
Laviosa has delivered to the project a range of different nanoclay systems. For example, they have performed the following tasks:
- collection of bentonite grades all over the world and their characterisation
- optimising of bentonite purification process in their laboratory pilot plant
- selection of bentonite grades according to the behaviour in the organophilisation reaction and purification steps.
2.3 Surface modification of nanoclays, for incorporation hybrid binder particles for water-based adhesives
In this task Laviosa has performed the following parts:
1) production of low exchanged nanoclays
2) scouting of in situ nanoclay formation application.
3) Trimethyl hydrogenated tallow ammonium modified nanoclays
Furthermore, UPV/EHU has developed a new surface modification method of nanoclays in order to ensure both good compatibility between the monomers and the clay surface, and to facilitate a chemical bond between the monomer and the clay modifiers. The compatibility with the monomer was found to be improved with the new surface modification method. They used clay from Laviosa LVF and clay from Southern Clay Cloisite Na+. In all cases the modification induced an increment of the interlayer space.
BYK performed silane modification of 43B clay from Laviosa. It was verified that the vinyl groups were really present at the edges in the modified 43B_BYK clay.
Compatibility tests were carried out for mixtures of silica and Vac, and clay and Vac, respectively. Unmodified silica and clay had a poor compatibility with VAc while organically modified silica and clay had a good compatibility with VAc. The work in Task 2.2 and task 2.3 are reported in Deliverable 2.2 “Development of surface engineered nanoclays for adhesives”.
2.4 Cost estimation for nanoclay production
The cost estimation has been conducted according to plan and is reported in deliverable 2.3 “Cost estimation of nanoclay production”.
2.5 Technical project management WP2
The technical project management has been realized through email correspondence, phone meetings and reviewing the risk log of the project. There has been one work plan change in WP2; Task 2.3 and 2.4 were extended to month 24 in order to increase the chances of incorporating the nanoclays in the adhesive hybrid binders, which also was achieved.
WP3 Development of hybrid binders with nanoparticles and nanoclays
Tasks:
3.1 Synthesis of hybrid binder particles with metal oxide nanoparticles for coatings
UPV/EHU has developed new hybrid binder particles with UV-absorbing nanoparticles from WP1. Both hybrid binders containing ceria and zink oxide have been developed.
The main conclusions from this work are:
• Stable acrylic/CeO2 latexes were obtained with different CeO2 content (from 0.5 up to 5%wt) and with high SC (up to 50%).
• Encapsulated morphology of the nanoceria in the polymer particles has been proved → No aggregation of nanoparticles in the film.
• Enhanced UV-Vis absorption in the films containing CeO2
• Incorporation of organically modified ZnO or CeO2 NP/NR improves the UV-Vis absorption at higher wavelengths.
3.2 Synthesis of hybrid binder particles with nanoclay particles for adhesives
The organically modified nanoclays synthesized in Task 2.3 have been used as building blocks in the synthesis of polymer/nanoclay hybrid binder dispersions. The polymerization was performed according to a standard D2 recipe of polyvinyl acetate from Casco, but with addition of nanoclays. The following conclusions were obtained:
• Encapsulated morphology of the nanoclays (43B, CMA16 and 43B+BYK) in the polymer particles has been proved after modification of the synthetic procedure.
• Enhanced water resistance properties have been found upon nanofillers incorporation.
• The exfoliation of the clay in the monomers is a key issue.
3.3 Synthesis of hybrid binder particles with silica nanoparticles for adhesives
The silica nanoparticles synthesized in Task 1.5 have been be used in this task. The main conclusions from this work are:
• Encapsulated morphology of the nanosilica in the polymer particles have been proved after modification of the synthetic procedure.
• Enhanced water resistance properties have been found upon nanofillers incorporation.
Task 3.1 task 3.2 and task 3.3 are reported in the Deliverable 3.1 “Development of hybrid binders for clear coatings and adhesives”.
3.4 Cost estimation for hybrid binder production
The cost estimation has been conducted according to plan and is reported in Deliverable 3.2 “Cost estimation for hybrid binder production”.
3.5 Technical project management WP3
The technical project management has been realized through email correspondence, phone meetings and reviewing the risk log of the project. There has been one work plan change in WP2; Task 3.1-3.4 were extended to month 27 in order to optimize the incorporation of ceria and zinkoxide into hybrid binder particles for coatings and nanoclay and silica in the adhesive hybrid binders.
WP4 Development of clear coating and adhesive formulations
Tasks:
4.1 Product specifications for new clear coating and adhesive systems
The specification for the clear coating and adhesive products have been discussed with the industrial partners and compiled by PRA. The results are summarized in Deliverable D 4.1 “Product specifications for clear coating and adhesive systems”.
4.2 Formulation of clear coating systems
PRA has developed new clear coating formulations, both based on UV-absorbing nanoparticle dispersions that can be added directly to water-based clear coating systems (4.2.1) and based on water-borne hybrid binders containing UV-absorbing nanoparticles (4.2.2).
Hybrid latex samples from WP3 and nanoparticles from WP1 were formulated into clear coatings for application onto panels for testing in WP5. After pre-formulation work 20 coating formulations were made of which 9 were based on hybrid latex containing nanoparticles and 11 on commercial latex blended with nanoparticles. Samples for accelerated ageing and exterior testing were prepared. Rheology and UV-Vis spectra of films have been studied.
4.3 Formulation of adhesive systems
The formulation of adhesive systems has been performed in this task. Standard PVAc formulations were mixed with colloidal silica samples or nanoclay samples. Hybrid binder from UPV/EHU was also used in the formulation of new adhesives. Adhesive formulation based on samples from UPV/EHU and physical blends from material from Eka and Casco have been formulated.
Task 4.2 and task 4.3 are reported in the Deliverable D4.2 “Development of clear coating and adhesive formulations”.
4.4 Technical project management WP4
The technical project management has been realized through email correspondence, phone meetings and reviewing the risk log of the project. There has been no work plan change in WP4.
WP5 Testing of nanoparticles, clear coatings and adhesives
Tasks:
5.1 Characterisation of nanoparticle and nanoclay systems
UV-Vis spectra of nanoparticle dispersions have been obtained both by the partners developing the new nanoparticle systems and by SP, in order to get comparable results for all systems. PRA has studied the UV-Vis spectra of clear coating films with UV-absorbing nanoparticles and of hybrid binders. Haze and colouring effects have been evaluated by AkzoNobel. TEM has been used by YKI and UPV/EHU to study the distribution of nanoparticles in hybrid binders and in clear coating films. The conclusions from this task are that new UV-absorbing nanoparticle systems have been developed that give good UV-absorbing properties and high transparency in the visible part of the spectrum. The haze and colouring effects vary for different systems and promising results have been identified by AkzoNobel. The distribution of nanoparticles in the clear coating films and in the hybrid binders is in most cases very homogeneous.
The results from Task 5.1 have been summarized in Deliverable D5.1 “Fundamental properties of nanoparticles and selection of systems for larger scale testing”.
5.2 Testing of clear coatings
5.2.1 Accelerated ageing
Test methods for accelerated ageing have been discussed and several different methods were used, for example EN927-6 (QUV) studied at PRA and ISO 11341:2004 (WoM) studied at SP. All paints formulated at PRA were applied on wood at SP.
Looking at the SEM images and looking at the changes in gloss and E for QUV and WoM (data not shown) it is clear that the microstructure change significantly for nanoceria containing coatings. This was the reason for the extra work study conducted in this task to understand the degradation phenomena of clear coatings containing ceria in accelerated weathering. This behaviour is so far not seen in natural exposure tests until month 21 in UK and Sweden respectively.
Extra work linked to understanding unexpected degradation of clear coating systems containing nanoceria in accelerated weathering was conducted during month 31-36. Two hypothesis were tested: (A) Degradation caused by photocatalysis; (B) Degradation caused by oxidation.
Energenics and SP (YKI) investigated point (A) and it was found, independently by both parties, that zink oxide and titania had a much higher photocatalytic activity than nanoceria.
The oxidative effect of the particles was investigated by SP (YKI) using the Rancimat method. The oxidation behavior varied a lot from high to low activity ceria depending on source, impurities and surface stabilizers. It probably means that the oxidative behavior could be controlled by the particles stabilizers or impurities instead of the nanoceria surface.
Neither of these two hypothesis are able to explain the degradation behavior found in weatherometer and QUV in presence of nanoceria. Another potential hypothesis raised at the final meeting is that the degradation depends on a combination of high “light dose”, high temperature and a lot of water. Possibly it is some kind of hydrolytic and thermal degradation in combination.
Once again this finding is so far (within 21 months) not seen in exterior field tests.
5.2.2 Natural exposure in field test
Within this task the performance of the developed clear coatings with UV-absorbing nanoparticles is evaluated by natural exposure field test according to EN 927-3.
The systems that are included in the natural exposure field tests were applied on wood panels and the panels were placed in the test fields in Sweden (SP) and UK (PRA) in July 2011.
Neither in UK or Sweden had a significant degradation occurred after 21 month. In hindsight, a less good binder would make it easier to distinguish between the evaluated novel additives.
These results have been summarized in Deliverable D5.2 “Accelerated and natural weathering of coatings”.
5.3 Testing and characterisation of reinforced wood adhesives
5.3.1 Testing of adhesive bonds
Several different reinforced wood adhesives based hybrid binders with either silica or clay nanoparticles have been evaluated according to the EN 204 (wet strength) and Watt 91 (heat strength).
The EN204 samples are treated with cold and/or boiling water in cycles. The WATT91 samples are heated to +80°C before pulling in the Alwetron.
The following key results for adhesives were found:
• WATT 91 was achieved for hybrid PVAc with hydrophobic silica.
• Hybrid PVAc with comonomer and nanoclay, increases the heat resistance and water resistance compared to a PVAc adhesive without reinforcement.
• Physical blends with 30-40% hydrophobic silica added to PVAc passed WATT 91.
These results have been summarized in the Deliverable D5.3 “Testing of adhesives”.
5.4 Technical project management WP5
The technical project management has been realized through email correspondence, phone meetings and reviewing the risk log of the project. Task 5.3 was delayed from month 30 to month 32 since promising results on adhesives needed further consideration. Unexpected degradation phenomena in accelerated ageing in presence of nanoceria prompted an extra study to clarify potential degradation mechanisms in accelerated ageing which was investigated between month 31-month 36.
WP6 Sustainability assessment
Tasks:
6.1 Assessment of potential toxicological/hazardous effect for humans/environment
The ecotoxicological results show that the nanoparticles used in WOODLIFE do not have any effect on the tested luminescent marine gram negative bacterium, Vibrio fischeri. The ecotoxicological results for Daphnia Magna showed no detected toxicity for ceria. Zinkoxide showed some toxicity well in-line with other studies.
The results are reported in the Deliverable D6.2 “Estimated toxicological/hazardous effect on the environment/humans”.
6.2 Design of process set-ups and outline of production systems to be assessed
The design phase was set up within month 24 and reported in the deliverable 6.1 “Outline of process set-ups and production systems to be assessed”.
6.3 Integrated Assessment of Social, Economic and Environmental performance
The environmental performance of the Woodlife coating and adhesive systems were assessed by means of environmental life cycle assessments (LCAs) by SP, in which impacts were assessed in the contexts of product life cycles: a window frame for the coating and a glue-laminated (glulam) wooden beam for the adhesive. The division between toxicity and other impact categories was done as the LCA methodology of today cannot characterize toxicity of nanomaterials sufficiently. The environmental assessments are part of full sustainability assessments, also including social and economic parameters.
The results suggest that there are potential environmental benefits of the coating and adhesive systems, if they enable wooden structures to replace non-wood alternatives. These results were strengthened by elaborate evaluations of uncertain aspects of the studied product life cycles, e.g. for the glulam beam: the end of life practices. Other published environmental assessments also emphasise the benefits of wooden building materials, but as the focus is often on global warming, benefits in other impact categories are more uncertain.
In environmental terms, the impact of the production of the adhesive or the coating is relatively small, and the impact from nanoparticle production is insignificant. This indicates that when optimising the environmental performance of the adhesives and coatings, the focus should be on optimising service life performance and addressing potential toxicological concerns , rather than on LCA results.
The economic assessment showed that the cost of the Woodlife coating, seen over the life cycle of a window frame, is potentially considerably lower than for conventional and comparable water-based coatings. As the assessment also showed that the cost of the coating is significant compared to the cost of purchasing windows, the Woodlife coating can contribute significantly to increased cost competitiveness of wooden building materials. For the Woodlife adhesive, the assessment showed that the cost of is similar to a conventional PVAc adhesive, the main uncertainty being the cost of nanoparticle production. Moreover, it was shown that the cost of the adhesive is a rather small part of the total cost of glulam beams and that steel frames in general are more cost competitive for internal roof constructions. However, the cost of both beams and frames largely depend on the specific application, and for certain applications glulam beams may be more cost-efficient
Fourteen million units of window frames were sold in Germany in 2003, the market shares of plastic, wooden and aluminium window frames being 54%, 21% and 20%, respectively, and as late as in the early 1990s, wooden frames had a greater market share than plastic frames. Therefore, the market potential for replacing plastic and aluminium window frames appears to be vast. As a consequence, there appears to be significant potential environmental and economic benefits of a successful Woodlife project. To some extent this potential, as well as the social sustainability potential of the Woodlife coating, will depend on how the supply chain of the final product is managed. The assessment in WP6 has provided guidance on important aspects to consider in the production and supply chain management of the coating in order to ensure good sustainability performance in environmental, economic and social terms.
In conclusions WP6 has shown that there are potentially significant sustainability benefits with the WoodLife products
– For coatings, in particular environmental and economic benefits
– For adhesives, in particular environmental benefits
The results are reported in the Deliverable D6.3 “Weighted Sustainability Assessment”.
6.4 Technical project management WP6
The technical project management has been realized through email correspondence, phone meetings and reviewing the risk log of the project. There has been no work plan change in WP6.
WP7 Technology demonstration and validation
Within WP7 we have scaled up the production of both hybrid binders and metal oxide nanoparticles, and prototype clear coatings and adhesives have been produced and tested.
7.1 Scale up of nanoparticle/nanoclay production
- BYK provided nanoceria for clear coat formulation.
- Energenics provided undoped nanoceria and iron-doped nanoceria for clear coat formulation.
- Sirris provided zinkoxide and cerium doped zinkoxide for clear coat formulation.
- Laviosa provided organo-modified clay for adhesive formulation.
- Eka provided organo-modified nano-silica for adhesive formulation.
7.2 Scale up of hybrid binder production
UPV/EHU scaled up hybrid binder production to 7.5 kg at Akzo Nobel pilot plant in Slough, UK. A coagulum free and stable latex was obtained with a solids content of 35%. With the characterization data reported it can be concluded that the latex obtained was very similar to the one synthesized at smaller scale at Polymat(UPV/EHU). The final particle size and the molecular weight were in the same range.
The morphology of either the dispersion or film was the expected one. Homogeneously distributed CeO2 nanoparticles could be found in the latex and the film. Furthermore, the UV-Vis absorption capacity of the films was satisfactory. It seems that our initial wood coating formulation works appropriately at larger scales.
7.3 Prototype clear coat manufacture
The production of the clear coats was fine. The performance is reported under task 7.5. The prototype clear coat is reported in Deliverable D7.1 “Prototype clear coat”.
7.4 Prototype adhesive manufacture
The adhesive prototypes that have been studied all contain different grades and amounts of colloidal silica and nanoclay. The prototype adhesive is reported in Deliverable D7.3 “Prototype adhesive”.
7.5Validation of functional performance, manufacturing and product maintenance costs
The main conclusions from the up-scaled clear coats were:
- All the formulations of the nanoparticles showed sufficient fineness but the gloss decreased dramatically. The transparency of the free films was at the same level as for the reference. The Fe doped CeO2 from Energenics was significant more yellow than the reference.
- The viscosity stability in enhanced temperature showed that all different nanoparticles were stable in the formulations.
- The blushing test showed that the nanoparticles made the films more sensitive (except from Sirris Ce doped ZnO) to water compared to the reference.
- The UV-Vis spectra of the free films show that the organic UV absorbers have the maximum peak at 340 nm. The reference with UV-abs/HALS has slightly higher peak compared to only UV-abs. The nanoparticles have higher absorption in the visible range compared to the organic UV absorbers.
- Accelerated weathering tests in Global UV 200 affected the gloss reduction more than the QUV. The reference panels became quickly very yellow in the Global UV 200 so the formulations with nanoparticles have lower delta E in the Global UV 200 compared than the reference. The nanoparticles from Sirris formed blisters after 800 hours. The addition of HALS in the reference has just slightly improvement on the gloss and the color change.
- The reference with and without HALS has generally less color change than the formulations with nanoparticles after 4 weeks in the QUV test. The Fe doped CeO2 was almost at the same level.
- The price for the coating with nanoparticles is significant higher, more than 60%. To be possible to sell on the market the life time needs to be considerably longer than the coating with conventional organic UV absorber. At this stage it is too early to make this conclusion. That needs longer natural weathering test at least more than 2 years.
The main results for adhesives were found:
• WATT 91 was achieved for hybrid PVAc with hydrophobic nanosilica.
• Hybrid PVAc with comonomer and nanoclay, increases the heat resistance and water resistance compared to a PVAc adhesive without reinforcement.
• Physical blends with nanoclay added to PVAc passed WATT 91.
This task is reported in Deliverable D7.3 “Performance of prototypes, manufacturing costs, and comparison to maintenance costs”.
7.6 Technical project management WP7
The technical project management has been realized through email correspondence, phone meetings and reviewing the risk log of the project. There has been no work plan change in WP7.
Potential Impact:
Potential impact, main dissemination activities and exploitation of results
How do we plan to maximize the commercial exploitation of the results of WOODLIFE?
SP (former YKI) has developed processes for production and stabilization of water-borne and solvent-borne ceria nanoparticles. It is expected that the nanoparticles can be used in other industrial sectors such as cosmetics, pharma, plastics. One obvious use would be for UV protection in other fields of applications. There is a discussion with relevant partners to transfer recipes and know-how that can be commercially exploited by the partner.
Energenics has patented (WO2012117238A1) processes for production of ceria and iron-modified ceria nanoparticles. Energenics is a SME already selling solvent-borne ceria nanoparticles for more efficient use of diesel in buses. The product portfolio is increased by having ceria nanoparticles that can be used in UV protection in clear coatings but also in other materials such as cosmetics, pharma and plastics. Energenics will market these new products to their costumers starting 2013.
Akzo Nobel Pulp and Performance Chemicals (former Eka Chemicals) has in the WOODLIFE project surface-engineered colloidal silica with silane chemistry. Eka is evaluating whether and how to protect the generated IPR in the best possible way. The silica is expected to be of interest in adhesives, paints and plastics. Eka is starting the marketing of these materials as we write this report.
BYK Chemie is specialized in surface-engineering and dispersion stabilization of various materials. In this project BYK has surface-engineered dispersions of ceria, zink oxide, silica and nanoclays. The results are protected in the patent application PCT/EP 2013/060095. The patent is a joint patent between UPV/EHU, SP, Energenics, Akzo Nobel and BYK. BYK has the right to the surface-engineering results. BYK has already samples ready to be shipped to customers and scale up and commercialize the potential products if the market request.
UPV/EHU is a university specialized in making hybrid dispersions. In this project UPV/EHU has develop latex with encapsulated ceria and zink oxide. The results are protected in the patent application PCT/EP 2013/060095. There is already an interest from companies to get access to these dispersions in the fields of paints and coatings and cosmetics. The timetable for the commercial use is presently under discussion between different partners within the consortium.
Eka Chemicals (now Akzo Nobel Pulp and Performance Chemicals) and Casco have developed physical blends of PVAc adhesive and surface modified colloidal silica that have passed key tests. Eka Chemicals is evaluating whether and how to protect the generated IPR in the best possible way. The marketing of these blends has already started and the blends are expected to be used in adhesives and paints.
In this project UPV/EHU with support from Casco has developed PVAc latex adhesives with encapsulated nanoclay that passed key adhesives tests. The results are protected in the patent application PCT/EP 2013/060095. Casco is evaluating the possibility to incorporate these latexes within their product range.
SP has performed LCA analysis of clear coatings and adhesives developed within the WOODLIFE project. The LCA show positive effects as follows:
- Glulam beams from wood better than steel
- Colloids and adhesive production insignificant in the total environmental LCA for glulam beams.
- Wooden window frames better than PVC or aluminium window frames
- Colloid and coating production insignificant in the total environmental LCA for wooden window frames.
In this project UPV/EHU with support from Casco has developed PVAc latex adhesives with encapsulated silica that passed key adhesives tests. The results are protected in the patent application PCT/EP 2013/060095. Casco is evaluating the possibility to incorporate these latexes within their product range.
SP has performed eco-toxicity tests using daphnia magna and vibrio fischeri on BYKs commercial ceria dispersions. The results are reported in the Ecotoxicity report within WOODLIFE. The results are incorporated into BYKs material safety data sheets and customer information.
In this project BYK has surface-engineered dispersions of ceria, zink oxide, silica and nanoclays from SP, Sirris, Energenics and Laviosa. The results are protected in the patent application PCT/EP 2013/060095. BYK and their material suppliers (listed above) have the right to the surface-engineering results. There are already samples ready to be shipped to customers and scale up and commercialize the potential products if the market request.
Casco has developed blends of silica and PVAc to increase heat resistance of their adhesive products. The results are protected in the patent application PCT/EP 2013/060095. Casco has samples available which can be shipped to customers on request.
Akzo Nobel Deco and Akzo Nobel Industrial Coatings have evaluated the UV protection of clear coating paints based on ceria encapsulated in acrylics. The results are protected in the patent application PCT/EP 2013/060095. Akzo Nobel is evaluating the needs from the market for these type of products.
Environmental impact
The global warming is one of the biggest environmental issues facing mankind today. There are strong indications that the emission of carbon dioxide (CO2) is the main cause for this.
CO2 in the atmosphere can be reduced by reducing emission or by removing partly the CO2 already present in the atmosphere. In other words by reducing carbon sources or by increasing carbon sinks. Wood can do both. Every cubic meter of wood used as a substitute for other building materials reduces CO2 emissions by 1.1 t CO2. Furthermore, every cubic meter of wood stores 0.9 t CO2. In total every cubic meter of wood saves a total of 2 t CO2. A 10 % increase in wooden houses in Europe would produce sufficient CO2 savings to account for 25% of the reductions (5.2 % from 1990s level) prescribed by the Kyoto protocol (Frühwald, Welling, Scharai-Rad, 2003, “Comparison of wood products and major substitutes with respect to environmental and energy balances”. ECE/FAO seminar: “Strategies for the Sound Use of Wood”, Poiana Basov, Romania, 24-27 March 2003).
-Thus, wood products can help to reduce the climate change for the following reasons; their raw material is renewable, they store the carbon trapped in the trees, they are produced with low CO2 processes and substitute for materials using high CO2 processes, they can be recycled and then burned as a substitute for fossil fuels and finally using wood products stimulates reforestation. Furthermore, the carbon storage can be extended by increasing the lifespan of wood products, for example by using the new clear coatings that have been developed in this project. It has been calculated that if wood consumption would increase by 4% every year in Europe, by 2010 an additional 1 500 million tonnes of CO2 (CEI-Bois “Tackle Climate Change Use Wood”, Roadmap 2010, 2004.) stored in wood products would be removed from the atmosphere. The target for Europe is to reduce the greenhouse gases by 8% by 2008-2012 compared to 1990 emissions. Extended use of wood products can contribute to reaching this target. We can conclude that the results from the WOODLIFE project may facilitate the extended use of wood products and thus reduction of greenhouse gases.
Economic and social impact
The wood working, coating and adhesive industries are a very important industrial sectors for Europe. In 2003 the total turnover of the EU15 wood working industries reached 147 000 million EUR, and the employment in this industry amounted to almost 2 million persons in the EU15 and another 680 000 people were employed in the sector in the new Member States (CEI-BOIS, the European Confederation of Woodworking Industries, 2004).
In Western Europe the domestic sales of coatings was in total 5.4 million tonnes in 2003, with a value of about 15.4 billion EUR (European Council of the Paint, Printing Ink and Artists´ Colours Industry (CEPE)). The EU coatings industries have a strong position, but increasing competition from overseas markets, where labour is cheap, is eroding the leadership of Europe. To change this trend the European industry needs to develop knowledge-based technologies that will increase the technology gap to foreign competitors.
The market for wood adhesives is estimated to be 4 million tons per year worldwide of which 600.000 tons are produced in Europe. About 1 million tons of PVAc and about 1 million tons of MUFs are produced per year. If the creep and thermosensitivity of the PVAc adhesives are sufficiently reduced it is expected that part of the more expensive MUF adhesives can be replaced by PVAc adhesives. It is also likely that an increased technology gap between Europe and the rest of the world will increase the amount of adhesives produced in Europe securing more jobs in Europe.
An increased growth of wood and an increased use of wood would reduce the increase of carbon dioxide in the atmosphere reducing the global warming. This would be an effective investment to reduce other potential future economic costs associated with higher sea levels, more frequent natural disasters, bigger spread of diseases like malaria and dengue fever. Costs associated with rebuilding major cities close to the coast, keeping lowlands above sea level can otherwise be gigantic. Moreover, the social impact when large amount of people having to leave coastal areas should not be underestimated.
It is expected that an efficient protection of wood against sun light degradation by incorporation of UV resistant colloids in clear coats, but also in translucent coatings, will decrease maintenance costs of joinery and “claddings”. It has been calculated that the 10 year maintenance cost for a wood window area of 22.000m2 for the object “Campeon” in Germany can be reduced with about 590 k€ if it is protected with the WOODLIFE coating instead of using a non-protected coating (Akzo Nobel Deco GmbH, 2009). In this way wood would become the preferred choice instead of PVC and aluminium and lead to the development of a more sustainable society and also securing more jobs in the woodworking industry. Furthermore the natural beauty of wood can be highlighted leading to that architects and consumers more and more will embrace wood as a beautiful and versatile material.
Dissemination, training and exploitation
Web-site
YKI has set up a web-site for the project, see www.woodlifeproject.com during the first six-month of the project. The website contains both a public area, and a private area that only the project partners have access to. The partners are continuously updating the web site with relevant documents.
Protection of IPR
A plan for the exploitation of results from WOODLIFE has been set up. Two patent applications have been submitted in the project:
- One patent application made by Energenics covering their ceria and iron-doped ceria development for UV absorption. The patent application number is WO2012117238A1.
- One joint patent application by UPV/EHU, Akzo Nobel, BYK, Energenics and YKI (SP) covering their development of encapsulated hybrid binders for adhesive and clear coating applications. The patent application number is PCT/EP 2013/060095.
Training, internal and external courses
The results obtained from WOODLIFE have been included in courses at PRA and at UPV/EHU in order to train people within the industrial community about the new developments in clear coatings and adhesives for wood materials.
Conferences and seminars
The results obtained from WOODLIFE have been disseminated through presentations at conferences and seminars. For example,
- Anwar Ahniyaz from YKI was an invited speaker in the conference 8th Coating Science International 2011 (COSI), 25-29 June 2011, Noordwijk, The Netherlands.
- Miren Aguirre from UPV/EHU presented at European Polymer Congress, 26 June -1 July 2011, Granada, Spain (http://www.epf2011.org/).
"Unexpected Enhancement of Polymerization Rate in Solution Polymerization with nano CeO2 particles"
- Yuri Reyes from UPV/EHU presented at the Second International Symposium Frontiers in Polymer Science, 29-31 May 2011, Lyon, France, “Reasons for some unexpected influences on branching of acrylic polymers”
- Miren Aguirre from UPV/EHU presented a poster entitled “Hybrid acrylic/CeO2 waterborne dispersions for coatings” at the Warwick Polymer Conference, 12 July 2012.
- Maria Paulis presented an oral presentation entitled “Obtaining organic-organic and organic-inorganic hybrids by miniemulsion polymerization”, at the Symposium in the KIT in Karlsruhe: “Nano-structure in disperse systems: production, characterization and functionality” (12 and 13 November 2012)
Furthermore, three papers related to WOOLDIFE have been presented at PRAs 8th International Woodcoatings Congress, 30-31 October 2012 in Amsterdam (http://www.pra-world.com/nandl/conferences/8th_woodcoatings_congress). The presentations from WOODLIFE was given a special session at the Congress, see below:
Wednesday 31 October 2012, 13.30 – 15.00
Session 6: Exterior Wood Coatings – EU Woodlife Project
Moderator: Peter Svane, Coating Consultancy
- Synthesis of Waterborne Hybrid Acrylic/CeO2 Nanocomposites for Wood Applications
Miren Aguirre
UPV/EHU, Polymat, Spain
- Nanoparticles for UV Protection of Clear Coatings – Field and Laboratory Trials
Dr Stig Bardage
SP Technical Research Institute, Sweden
- Environmental Evaluation of a Clear Coating for Exterior Wood Products: Toxicological Testing of Nanoparticles and Life Cycle Assessment
Gustav Sandin
SP Technical Research Institute, Sweden
In total 21 dissemination activities have been performed from the WOODLIFE project.
Furthermore, the following 9 papers with results from the WOODLIFE project have been accepted or submitted:
“Surfactant-Free Miniemulsion Polymerization of n -BA/S Stabilized by NaMMT: Films with Improved Water Resistance”, udrey Bonnefond, Maria Paulis, S.A.F. Bon, Jose R. Leiza, Langmuir, 7/29, p.2397-2405 2013.
“UV screening clear coats based on encapsulated CeO2 hybrid materials”, Miren Aguirre, Maria Paulis, Jose R. Leiza, Journal of Materials Chemistry, 1, p.3155-3162 2012.
“Encapsulation of Clay Within Polymer Particles in a High Solids Aqueous Dispersion”, Yuri Reyes, Pablo J. Peruzzo, Mercedes Fernández, Maria Paulis, Jose. R. Leiza, Langmuir, 2013. Accepted
“High solids content hybrid acrylic/CeO2 latexes with encapsulated morphology assessed by 3D-TEM”, Miren Aguirre, Maria Paulis, Jose R. Leiza, Teresa Guraya, Maider Iturrondobeitia, Ana Okariz, Julen Ibarretxe, Macromolecular Chemistry and Physics, 2013, Accepted
“Effect of the incorporation of modified silicas onto the final properties of wood adhesives”, A. Bonnefond, Y. Reyes, P. Peruzzo, E. Ronne, J. Fare, M. Paulis, J.R. Leiza, Macromolecular Reaction Engineering, 2013, Accepted
“Nanoparticles for UV protection of clear wood coatings – field and laboratory trials”, Stig Bardage et al, Surface Coatings International, Accepted, 2013
“Synthesis of Waterborne Hybrid Acrylic/CeO2 Nanocomposites for Wood Applications”, Miren Aguirre et al, Surface Coatings International, Accepted, 2013
“NTA-stabilized cerium oxide nanoparticle dispersion for UV screening applications”, Johansson Salazar-Sandoval, Eric; Johansson, Mats; Ahniyaz, Anwar, ACS Applied Materials & Interfaces, 2013. Submitted
“Beneficial incorporation of nanoclay in PVAc adhesives for wood applications”, Pablo J. Peruzzo, Audrey Bonnefound, Yuri Reyes, Mercedes Fernández, Joanna Fare, Erik Ronne, María Paulis, Jose. R. Leiza, International Journal of Adhesion and Adhesives, 2013, Submitted
In addition to this one thesis publication has been produced within the WOODLIFE project:
Licentiate thesis
“Improved environmental assessment in the development of wood-based products
Capturing impacts of forestry and uncertainties of future product systems”
Gustav Sandin, SP Technical Research Institute, Sweden
List of Websites:
www.woodlifeproject.com Coordinator: Marie Sjöberg, SP Technical Research Institute, Sweden, marie.sjoberg@sp.se, Technical Project Manager: Anders Larsson, SP Technical Research Institute, Sweden, anders.larsson@sp.se