Abstracts

Woodcoatings Congress 2021

 

1.1 A novel non-isocyanate-based and formaldehyde-free technology for solvent- and water-borne systems

 

Andreas Hermes, Allnex, Germany

 

Based on our extensive background, Allnex has developed water-borne and solvent-borne formaldehyde free crosslinkers paired with tailored backbone binders for ambient dried, wood coatings. The new technology reduces any exposure to hazard materials in production while diminishing release of hazard substances during drying process. The main binder technologies include economical short oil alkyd or advanced acrylic resins allowing fully customized solutions. This novel technology has increased pot life allowing it to be applied on traditional coatings lines without any changes in required.  Superior hardness development results in excellent early print resistance and extra-ordinary chemical resistance compared to current used systems. Both systems, solvent borne as well as water borne, can be formulated into clear or pigmented coatings. This leading edge technology can fulfill the highest requirements of the European furniture industry.

 

1.2 LIFE-Biopaint, a European project for advanced biobased UV-cured coatings

 

Dr Marcello Vitale, IVM Chemicals, Italy

 

IVM CHEMICALS is building the most advanced paint production line in the world, for 100% UV products

fully automated - closed circuit - no VOC emissions - minimal waste - optimized dispersion and component sizing - NO BATCH-TO-BATCH VARIABILITY

We are also developing specific biorenewable resins characterized by
- very low variability enabled by new process
- the first use of new biorenewable raw materials in 100% UV products
- a vertically integrated, co-located production of resins and paints

THE LOWEST ENVIRONMENTAL IMPACT FOR 100% UV PRODUCTS (as measured by LCA)
These cutting-edge innovations are the objective of LIFE-Biopaint, a 3 million euros project funded by LIFE, the EU program dedicated to fostering the most promising innovations with broad positive impact on the environment.
The presentation illustrates process and product innovations and details properties and advantages of the coating products obtained, that help answer the growing consumer request for renewable and sustainable solutions in their living space.

 

1.3 Fire retardant woodcoatings inspired by nature - made with microfibrillated cellulose

 

Dr Claudia Schirp, Fraunhofer WKI, Germany

 

The main objective of the project FireCellCoat is the development of a bio-inspired, fire retardant wood coatings based on microfibrillated cellulose that will protect wood-based building products in interior and exterior applications.
FireCellCoat’s approach is to construct a novel fire-retardant structure draws inspiration from Canary pine bark architecture and chemistry - nature’s outstanding solution against fire. Our principal hypothesis is that by designing a similar type of macro-scaled multilayer structure we can develop a wood coating that is able to delay ignition and fire propagation. To achieve our objective, microfibrillated cellulose will be used in combination with inorganic components. This will be complemented by a chemical approach involving copolymerization techniques to protect the fire-retardant material against leaching from the coatings.
In summary, FireCellCoat contributes to the biobased economy by providing a novel approach to achieving durable, high-performance fire-retardant materials based on sustainable resources.

 

1.4 Contributing to the development of more sustainable solutions for wood coatings

 

Dr Eva Tejada, Covestro, Spain

 

With the EU green deal targeting to achieve climate neutrality by 2050 the need to reduce environmental impact of industrial processes like wood coatings is increasing. With the help of tools like the Life Cycle Assessment (LCA), we will demonstrate how water-borne polyurethane systems can help us reduce the carbon footprint of wood coatings in comparison to two component solvent-borne polyurethane. Hereby we will highlight the latest developments like Bayhydur® quix which can additionally contribute to a significant reduction of the environmental footprint in a high performance wood coating system by accelerating the drying process. On the other hand, we will present different available solutions to further reduce CO2 emissions by using of partially bio-based raw materials both for solvent-borne and water-borne technologies.

 

1.5 New waterborne epoxy resin system for low VOC wood primer and sealer

 

Gunda Kuhlmann, Hexion, Germany

 

Reducing Volatile Organic Compound (VOC) emissions is the main driver for using waterborne binders in wood coating applications. Since conventional, waterborne binder technologies are facing some performance limitations, the next level of innovation is to use waterborne epoxy resin systems that enable high film-build primers and sealers with superior grain raising resistance.
A newly developed waterborne resin system and a starting formulation will be introduced that provides good performance regarding tannin blocking, grain raising resistance, sandability and hardness development. The new waterborne epoxy systems can be used to increase resource efficiency and productivity in wood coatings.

 

1.6 High solids acrylic dispersions: the evergreen challenge to replace solvent-borne alkyds in wood coatings turned into sustainable reality

 

Dr Bas Lohmeijer, BASF, Germany

 

A brand-new generation of high solids (60%), core-shell-type acrylic polymer dispersions enables access to new formulation spaces for waterborne wood coatings. Higher volume solids and more Newtonian rheology allow application properties and hiding power of, and beyond, classical solvent borne alkyd systems. The binder’s polymodal particle size distribution leads to an increased wet and final dry layer thickness to gain a true one coat hide. The unique paint rheology results from the specific interaction of associative thickeners with this tailored particle size distribution. Labor time savings in finishing paints jobs and better final surface characteristics result from better hiding without compromising in open time. The core-shell nature of the binder particles is adamant for improved blocking resistance and low VOC levels in wood coatings formulations. A lower carbon footprint of the polymer dispersion and the formulated wood coatings results from less water transported.

 

2.1 Rendering Magnetism on Wood through Coatings

 

Rajesh Shah, Asian Paints, India

 

Wood as a substrate is an important element in decorating a home.  As much as coatings for masonry create opportunities for beautifying and protecting homes, use of coatings on wood have been no less in terms of offering protection through exceptional stain and scratch resistance.  While wall finishes have diversified into Faux finishes to enhance décor in homes, enhancing these options over wood coatings offers a world of possibility to accentuate décor in homes. Wood however being insulator remains benign on accepting any miniature beautification items such as magnets, hanging displays typically used either on household metal items such as refrigerators, washing machines or affixed by drilling through a coating and fixing creating dust.
In this paper, the authors discuss some unique approaches to induce magnetism in wood coatings with no deterioration in coating aesthetics and yet enhancing their capability significantly for home décor and generating conveniences in living spaces.

 

2.2 Self-Healing Materials: A Novel Solution for Durable Wood Coatings

 

Eric Brouwer, Croda, The Netherlands

 

The continuous market drive for more durable materials with extended lifetimes has stimulated the development of Self-Healing materials. Self-Healing materials offer a novel solution to improved durability and sustainable product design, but existing approaches to achieve the effect are often based on the use of harsh, reactive systems.
Our novel Self-Healing polyol is 90% bio-based and able to create waterborne and solvent borne polyurethane coating systems for wood protection. By utilising an intrinsic healing mechanism based on hydrogen bonding, these polyurethane coatings repeatedly recover from both deep and superficial scratching in the same damage area. As demonstrated using microscopy and water ingress tests, healing occurs at room temperature and is accelerated by slightly elevated temperatures providing long-lasting wood protection.
The versatility of the polymer design allows tweaks in the formulation to be made, leading to a wide variety of formulation possibilities to fit a range of different applications.

 

2.3 Fire protection tests: cone versus SBI

 

Dr Birgit Hillebrand-Schmidt, Mocopinus, Germany

 

After the conflagration of Grenfell Tower in June 2017 the demand for fire protective systems increased rapidly. This may be a limiting factor for the use of wood installations in official buildings. Therefore many paint suppliers develop wood coatings with fire protective characteristics.
The building products directive asks for fire classification tests according to DIN EN 13501 called "SBI-Test". For this test method construction elements of more than 1 m2 are needed. Sample preparation takes a lot of time. That is why paint laboratories prefer a test method needing small samples (10x10cm) called "Cone-Test" (ISO 5660-1) with additional calculation to predict measurement values of "SBI-Test".
Mocopinus is a manufacturer of wood coatings. During development of fire protective wood coatings Mocopinus did several SBI- and Cone-Tests of identical samples. It was found out, that the calculation model between SBI- and Cone-Test has to be modified when testing wooden samples.

 

2.4 Aluminum oxide nanocomposite wax powders for improved scratch resistance

 

Richard Czarnecki, Micro Powders, the United States of America

 

Micronized waxes can be highly engineered materials that are engineered to deliver a specific function to the surface of a coating.  With proper design, the mobility of the wax particle can be optimized to efficiently stratify at the surface, where physical durability properties such as scratch resistance are required.
This paper presents a novel, patent-pending approach to wax additive design based on multicomponent composites containing nano-scale aluminum oxide particles.  Data will be presented to show the dramatic improvement in scratch resistance vs. the unmodified wax powder.  Data will also be presented to demonstrate that a wax/aluminum oxide nanocomposite powder is actually a more efficient way to bring the aluminum oxide to the coating surface, as compared to directly formulating aluminum oxide into the coating.
This paper will compare performance against PTFE wax additives, and will demonstrate that nanoalumina composite waxes provide similar performance for applications where PTFE is being avoided.

 

2.5 A breakthrough innovation for low-toxicity crosslinking

 

Dr Patrick Stals, DSM, The Netherlands

 

The quest for a crosslinker for waterborne paints that combines both effective crosslinking at room temperature and safe handling has been universally recognized as one of the major challenges in the coating industry of the last decades. Ideally, such a crosslinker is also easy to use, displays a prolonged potlife and is compatible with a wide range of binders and applications.
In this contribution DSM proudly presents the pinnacle of a significant R&D effort, with the introduction of a new class of crosslinkers. These crosslinkers are non-mutagenic, striking an unprecedented balance between favorable labeling and crosslinking performance. Therefore, these new crosslinkers solve many of the deficiencies of existing crosslinkers, while providing a wide formulation latitude and suitability for a range of applications.
The performance of these new crosslinkers will be shown for several formulations and curing conditions and for a variety of applications.

 

2.6 Bio-based high-performance waterborne urethane dispersions for Isocyanate free coating systems

 

Dr Gabor Edodi, Lubrizol, The United States of America

 

New functional waterborne urethane dispersions were designed to exceed the performance of current market leading 2-component  wood coatings and meet the highest standards for environmentally friendly coatings.  The new resins have high renewable carbon content (up to 40%) and can be formulated and used without hazardous ingredients found in most 2K products, such as triethylamine, isocyanates, aziridines, or adipic acid dihydrazide (ADH).  The polymers were developed to have efficient crosslinking with environmentally friendly carbodiimide type crosslinkers and long pot life. They contain high performance polyols based on polyamide technology and can be formulated to low VOCs (<100 g/L-EU). The high solid content of the urethane dispersions (>45%) can enhance coating solutions by improving dry time and by reducing paint application workload due to higher film build. The coatings were benchmarked against an array of commercial products focusing on aesthetic qualities and protective features including gloss, hardness, chemical and scratch resistance.

 

3.1 Pushing water-in-oil technology to the limits

 

Dr Gerard van Ewijk, AkzoNobel, The Netherlands

 

The share of waterborne technology in architectural wood coatings is steadily growing, yet there are markets where solventborne products are still the preferred choice. Through water-in-oil (WiO) technology, we can offer significantly more sustainable products in these markets. After years of pushing the boundaries of water-in-oil technology, we are now at a stage where water-in-oil woodstains have up to 50% lower VOC content compared to conventional woodstains.
In this presentation I will highlight the latest state of affairs with water-in-oil woodstains in AkzoNobel. Scientific and practical insights will be given as to where the limits of WiO technology are, and the challenges in dealing with water-in-oil technology on an industrial scale will be briefly addressed. Finally the sustainability benefits of WiO woodstains will be quantified, showing that WiO woodstains can have a 40% Carbon Footprint reduction compared to conventional woodstains.

 

3.2 Clay-based Additive for Formulations of Low or Zero Biocide and VOC Paint

 

Solvita Kostjukova, ALINA, Latvia

 

A novel metal-free and UV protective clay-based (so-called organoclay) additive to the coating matrix has been developed. The raw materials for the production of additiv are naturally occurring swelling clay minerals with traces of dolomite, quartz, and carbonates. The absence of organic solvents during the production makes the additive green and environmentally-friendly and it complies with the Ecolabel requirements, including Blue Angel, Nordic Swan, French Décret and the EU Ecolabel.
The additives are available in water or oil slurry forms, which can be dispersed in waterborne, oil based or polymer systems. As a result paint formulations containing low or zero VOC and low or zero biocides have been developed, which are compliant with EU Ecolabel certification standards. The characterisation of the final formulations and efficiency in use were performed, including durability of finished coatings and outdoor exposure tests of the newly developed “organoclay supported” paint formulations.
Supported: LIFE-ALFIO LIFE17 ENV/LV/000318.

 

3.3 New lignin stabilizer for unmet needs

 

Dr Delphine Kimpel, BASF, Germany

 

Lignin stabilizer based on the well-established Tempo chemistry is widely used in numerous applications to prevent lignin against unwanted discoloration and further loss of mechanical properties of the final wooden substrates. This current stabilization path shows its limits such as incompatibility on oak, due to dissolution of the extractives, own color that hinders its use on very light wood species and, last but not least, detrimental interactions with radical-free curing systems, that leads to loss of inter-coat adhesion.
To overcome these well-known drawbacks, a new lignin stabilization concept has been developed to meet the current as well as the new requirements from various markets like furniture, joinery and automotive.
The technical features and the performances of this new lignin stabilizer will be shown in this presentation.

 

3.4 Lowering the carbon footprint of alkyd based coatings with no compromise for quality with TallOilFattyAcid as building block

 

Patrick Van Waes, Kraton, The Netherlands

 

Tall Oil Fatty Acids (TOFA) originating from sustainable pine forests in the Nordics are high quality building blocks for alkyd and alkyd modified binder systems which combine their unique functional properties with the highest level of  sustainability. Its minimal carbon footprint equivalent of 0.691 CO2 eq/Kg due to the low land-use impact, 100% bio-based content, non-food usage and non-genetic modification makes it an ideal product for future developments in sustainable woodcoatings. This paper will highlight the renewable production process starting from crude tall oil and explain its chemical composition resulting in technical benefits such as improved drying time and increased hardness which are needed for functional woodcoatings. The low carbon footprint of TOFA allows a reduction in CO2 eq by a factor more then 10. Life Cycle Analyse comparing TOFA with veg based oils provides the required scientific evidence and will be shared in this presentation.

 

3.5 Influence of coating on biocides migration and depletion from treated wood exposed to natural weathering.

 

Oussemah Ouali, FCBA, France

 

Outdoor wooden joineries are subject to climatic factors having a direct impact on their service life. Biocides from treated wood are prone to degradation and leaching, causing an inevitable loss of durability over time. The application of a wood coating is mandatory for treated woods before their use outdoors. Known for their protection against abiotic and biological aggressions, coatings may have an additional role in biocides fixation within wood. A first internal study of interaction between biocides from treated wood samples and an acrylic coating showed an unexpected migration of biocides from the wood to the coating layer at the application step. A weathering experiment was also carried out using three wood preservative products for a surface treatment of Scots pine sapwood samples, with the half painted with an acrylic coating. Biocides analysis in wood samples and rainwater runoffs showed a clear difference of depletion between coated and uncoated samples.

 

3.6 The Long Road to Camelina

 

Dr Christian Walter, DAW, Germany

 

Alkyde-derived coatings for wood have always had a portion of their feedstock grown in agriculture, which places them, from a sustainable point of view, way ahead of petrochemically derived binders. Looking more closely at the sources of the alkyde-binders, one starts to observe differences which go beyond mere technical properties of a binder: the crop is the binder derived from, the location where this crop is cultivated, the exact conditions of cultivation (i.e. pesticide usage).
At the same time, there are the aforementioned technical aspects which also have to fit into the profile: good performance in stains, wood oils and varnishes, pricing and, last but not least, availability
We set out to establish a supply-chain for a highly sustainable binder in 2014, trying to define a new benchmark for sustainable binders for woodcoatings and the presentation will show the process as this concept developed from a vague idea to reality.

 

4.1 Structured wood surfaces for flooring under the microscope - Coatings to obtain high resistance and natural look and feel

 

Dr Gerhard Grüll, Holzforschung Austria, Austria

 

Surface structuring of wood flooring such as brushing is a means of emphasising the natural structure of wood and giving it a natural look and feel. The aim of the project Surf~Parquet was the improvement of the durability against pollution and chemical influences while sustaining the natural look and the haptic features of the structured wood surface of floors. 3D topography of structured surfaces of oak, larch and maple was studied with SEM and light microscope. Coatings were used to improve the resistance of the surfaces, weak spots in the coatings were analysed by microscopy and based on this application techniques were improved. In the project, several variants of structured wood flooring with uniform matt coating films over the topography were obtained, which resulted in a natural look and feel as well as high resistance.

 

4.2 Predicting the long-term performance of wood coatings

 

Dr Stefan Friebel. Fraunhofer WKI, Germany

 

There are numerous standard methods for accelerated testing the durability of coatings. Although the correlation of artificial and natural weathering of metal and plastic coatings is good, it is not satisfactory for wood exterior coatings. This is primarily due to the heterogeneous material wood. In addition, different types of wood reveal large variations in swelling and shrinking movements caused by humidity changes. WKI takes an approach that examines the change in the mechanical characteristics of the coating over the weathering time. This allows a measurement of a more realistic acceleration factor.
This includes an application of an alternative artificial weathering cycle, which more precisely simulates seasonal weather fluctuations, than current standardized weathering cycles do. The developed method was applied to different varnishes and the first results indicate that the method allows more reliable correlation regarding the failure time between artificial and natural weathering than the current standardized methods do.

 

4.3 Change in gloss, colour, hardness and elongation at break as useful indicators of exterior wood coating failure

 

Dr Laurence Podgorski, FCBA, France

 

Wood coating failure is assessed mainly using visual parameters (cracking, flaking, blistering) as recommended in EN 927-2. In this paper early changes of coatings which ultimately lead to coating failure were tracked. Change in colour, gloss, Persoz hardness and tensile properties of coatings were analysed during weathering. The loss of gloss was due to micro-cracks invisible to the naked eyes that developed before cracking was noticed. The decrease in gloss was paralleled by the increase in hardness. For the first time a correlation was established between  hardness and gloss variations. This shows that the loss of gloss reflects a change in the mechanical properties of polymers. Therefore, a special attention should be given to gloss variations to anticipate cracking development and time for  maintenance. Results are discussed in connection with change in colour and tensile properties of the coatings. These different findings call for a revision of EN 927-2:2014.

 

4.4 On-site measurement of dry paint film thickness on wood

 

Peter Svane, Coating Consultancy, Denmark

 

On-site measurements of dry paint film thickness (DFT) serve to check whether a coating specification has been followed or to explain paint failure. It is fairly simple to measure the DFT on steel and other metal substrates where magnetic or eddy-current methods can be applied.  On wood, however, the measurements are more complicated. Wood is a particularly difficult material because of its porous structure and its rough surface. Under some circumstances can even the moisture content and the swelling and shrinking of wood with changing moisture complicate the measurement further. The principles of DFT-measurements are given in ISO 2808, and in its latest edition (2019) an annex C has been inserted “Factors affecting the precision of readings obtained when measuring on wooden substrates”. Annex C is a great step forward, but the result of a measurement depends on several details still not described.

 

4.5 The influence of exposure orientation and inclination on the service life of wood coatings

 

Dr Boris Forsthuber, Holzforschung Austria, Austria

 

The exposure angle and exposure orientation greatly affect the service life of wood coatings. As part of the SERVOWOOD project, a multifaceted exposure rig (MFER) for outdoor weathering was designed that allows for exposure of coated panels in nine different directions, vertically and 45° inclined in each compass direction and horizontally on top of the rig. 2 coating systems with different dry film thicknesses were exposed for 4 years at three different locations in Europe. It was agreed among the consortium that cracking is the main failure mechanism determining the service life of wood coatings. The time to failure (ttf) approach was used for quantifying the service life of coatings. The results revealed very different ttf values depending on the different exposure direction and inclination. From these data, factors were calculated according to the ISO 15686-8 that allow an accurate estimation of the service life of wood coatings.

 

4.6 Water vapour permeability of modern water borne industrial woodcoatings, test method, comparison with water permeability and durability results.

 

Niels Lutke Schipholt, SHR, The Netherlands

 

For over 25 years SHR has been involved in performance testing of water based industrial paint systems for joinery applications. Performance requirements for coating systems specified for the Dutch construction practice focus on water permeability and durability. Although water permeability and durability provide a great deal of information it is not always possible to explain cases of coating failure that occasionally occur in practice. Therefor, water vapour permeability was studied and compared to other available test results from lab and field. A test method was developed to prepare test samples from EN927 standard size test panels and to measure water vapour permeability by the wet cup method. Main goals of this study are to answer the following questions:
Are liquid water permeability and water vaper permeability related?
Do differences in water vapour permeability provide better understanding of coating performance in practice?

 

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