Improvement of the durability of clear coatings by grafting of UV-absorbers on to wood

Kiguchi, Makoto; Evans, Philip D.; Ekstedt, Jan; Williams, Ralph E.; Kataoka, Yosuke

doi:10.1007/bf02700407

Cited by 30 publications

(21 citation statements)

References 7 publications

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“…More recent field testing has confirmed the disappointing results of earlier trials. For example, Kiguchi and co-workers found that silicone-urethane and polybutadiene varnishes on sugi failed within 6 months of exterior exposure in Tsukuba, Japan [12]. A fluorine clear coating failed within a year of outdoor exposure [13].…”

Section: Longevity Of Clear Coatings On Woodmentioning

confidence: 99%

“…The majority of published research in this area has employed either benzophenone or triazine UV absorbers containing an epoxy group. These UV absorbers can be permanently bonded to wood at high temperatures in the presence of an amine catalyst [12,23,101]. Grafting of epoxy-functionalized UV absorbers to wood protected wood from photodegradation and also improved the performance of clear coatings on modified wood surfaces ( Figure 11).…”

Section: Photostabilizersmentioning

confidence: 99%

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The Search for Durable Exterior Clear Coatings for Wood

et al. 2015

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Abstract:The goal of a durable exterior clear coating has eluded generations of coatings technologists, despite long-standing desire amongst the public for such a coating. The journey towards this goal initially focused on modifications to coating formulation, but took a completely different direction when it was found that a UV-transparent silicone clear coating on wood modified with chromic acid met consumer expectations of coating durability. This finding sparked world-wide interest in wood pre-treatments as a way of enhancing the durability of clear coatings. This interest initially focused on transition metal compounds, but has now shifted in the direction of organic and inorganic photostabilizers or even more drastic pre-treatments. Pre-treatments that dimensionally stabilize wood, protect it from microbial degradation and photostabilize lignin, when combined with flexible, photostable, coatings provide the next way-stop on the journey towards achieving the goal of durable exterior clear coatings for wood. This paper reviews this journey, drawing upon our research and that of other groups who have focused on this elusive goal. OPEN ACCESSCoatings 2015, 5 831

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Section: Longevity Of Clear Coatings On Woodmentioning

confidence: 99%

Section: Photostabilizersmentioning

confidence: 99%

The Search for Durable Exterior Clear Coatings for Wood

et al. 2015

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“…The water synergistically interacts with solar radiation and causes atmospheric degradation of the wood surface [4][5][6], as well as dimensional changes and crack formation [7]. Modification in the form of hydrophobization can increase the natural durability of wood against biotic and abiotic damages on its exterior [8,9].…”

Section: Introductionmentioning

confidence: 99%

Efficacy of Hydrophobic Coatings in Protecting Oak Wood Surfaces during Accelerated Weathering

et al. 2017

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Abstract:The durability of transparent coatings applied to an oak wood exterior is relatively low due to its anatomic structure and chemical composition. Enhancement of the protection of oak wood against weathering using transparent hydrophobic coatings is presented in this study. Oak wood surfaces were modified using UV-stabilizers, hindered amine light stabilizer (HALS), and ZnO and TiO 2 nanoparticles before the application of a commercial hydrophobic topcoat. A transparent oil-based coating was used as a control coating system. The artificial weathering test lasted 6 weeks and colour, gloss, and contact angle changes were regularly evaluated during this period. The changes in the microscopic structure were studied with confocal laser scanning microscopy. The results proved limited durability against weathering of both tested hydrophobic coatings. The formation of micro-cracks causing the leaching of degraded wood compounds and discolouration of oak wood were observed after 1 or 3 weeks of the weathering test. Until then, an oil-based coating film had protected the wood sufficiently, but after 6 weeks the wood was fully defoliated to its non-homogenous thickness, which was caused by the presence of large oak vessels, and by the effects of specific oak tannins. Using transparent hydrophobic coatings can prolong the service life of the exteriors of wood products by decreasing their moisture content. Without proper construction protection against rainwater, the hydrophobic coating itself cannot guarantee the preservation of the natural appearance of wood exteriors.

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“…Because of these disappointing findings, the California Redwood Association stopped recommending clear finishes for redwood used outdoors. Subsequent testing in several countries have confirmed the poor performance of clear coatings on wood exposed outdoors-most fail within 2 years in temperate climates, and failure within a year is common in tropical climates [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

“…Hence, the most obvious way to improve the performance of clear coatings on wood is to photostabilize the wood surface before applying clear coats. Numerous studies using a variety of photostabilizers have confirmed the veracity of such an approach [11,12,15,[17][18][19]. Indeed, the best photoprotective systems can easily double the lifetime of clear coatings on wood, but such an increase falls short of what is needed.…”

Section: Introductionmentioning

confidence: 99%

Improving the Performance of Clear Coatings on Wood through the Aggregation of Marginal Gains

et al. 2016

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Remarkable increases in the performance of complex systems can be achieved by a collective approach to optimizing individual factors that influence performance. This approach, termed the aggregation of marginal gains, is tested here as a means of improving the performance of exterior clear-coatings. We focused on five factors that influence clear-coating performance: dimensional stability of wood; photostability of the wood surface; moisture ingress via end-grain; coating flexibility and photostability; and finally coating thickness. We performed preliminary research to select effective wood pre-treatments and durable clear-coatings, and then tested coating systems with good solutions to each of the aforementioned issues (factors). Red oak and radiata pine panels were modified with PF-resin, end-sealed, and thick acrylic, alkyd or spar varnishes were applied to the panels. Panels were exposed to the weather and the level of coating defects was assessed every year over a 4-year period. All of the coatings are performing well on PF-modified pine after 4 years' outdoor exposure. In contrast, coatings failed after 2 years on unmodified pine and they are failing on PF-modified oak. We conclude that our approach shows promise. Future research will build on the current work by developing solutions to additional factors that influence clear-coating performance.

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Improvement of the durability of clear coatings by grafting of UV-absorbers on to wood

Cited by 30 publications

References 7 publications

The Search for Durable Exterior Clear Coatings for Wood

The Search for Durable Exterior Clear Coatings for Wood

Efficacy of Hydrophobic Coatings in Protecting Oak Wood Surfaces during Accelerated Weathering

Improving the Performance of Clear Coatings on Wood through the Aggregation of Marginal Gains

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