Alternative to latent catalysts for curing UF resins used in the production of low formaldehyde emission wood-based panels

Costa, Nuno; Pereira, João; Martins, Jorge; Ferra, João; Cruz, Paulo; Magalhães, Fernão D.; Mendes, Adélio; Carvalho, Luísa

doi:10.1016/j.ijadhadh.2011.11.003

Cited by 66 publications

(33 citation statements)

References 11 publications

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“…These early formed bonds are destroyed during the pressing stage. Note that Costa et al (2012c) showed that a standard E1 UF resin with 3 wt-% of ammonium sulphate had a pot life of 2 h. When solid acids were used, on the other hand, resin pre-cure did not occur, since the catalyst remained in solid powder form in the mat and therefore not in contact with the resin. During the pressing stage, the water vapour dissolves the solid acid mobilising the hardener, which results in resin cure.…”

Section: Hexamine As Formaldehyde Release Agentmentioning

confidence: 99%

“…However, as shown by Costa et al(2012c), in service, boards produced with resins catalysed by acids will have a lower formaldehyde content, during their life time, due to the absence of hexamine. Formaldehyde content values of boards produced with latent and acid catalysts were according to previously published results (Costa et al 2012c). The efficiency of ammonium sulphate as catalyst is strongly related to the concentration of free formaldehyde present in the resin.…”

Section: Hexamine As Formaldehyde Release Agentmentioning

confidence: 99%

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Formaldehyde emission in wood based panels: effect of curing reactions

Costa

Pereira

Ferra³

et al. 2014

International Wood Products Journal

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The influence of hexamine formed as byproduct during the UF cure was ignored in the past. However, with the increasing interest on low formaldehyde emission boards, this issue has become more pertinent. Formaldehyde release from hexamine degradation is extensive and could limit the success of the development of low formaldehyde emission adhesives if the conventional latent catalysts remain in use.In this study, formaldehyde released from recycled wood, hexamine and cured UF resin was assessed. Citric and oxalic acid, in solid form, were used as catalysts for UF resin in the production of particleboard. Mats with solid acids are less susceptible to resin pre-cure than with a latent catalyst. However, they can have higher formaldehyde emissions than latent catalyst. When both catalysts were used, combined with an ultra-low formaldehyde to urea molar ratio resin the internal bond was improved and formaldehyde content was below 4 mg per 100 g of oven dry board.

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Section: Hexamine As Formaldehyde Release Agentmentioning

confidence: 99%

Section: Hexamine As Formaldehyde Release Agentmentioning

confidence: 99%

Formaldehyde emission in wood based panels: effect of curing reactions

Costa

Pereira

Ferra³

et al. 2014

International Wood Products Journal

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“…Latent catalysts, in the presence of water (which promotes dissociation), react with formaldehyde forming an acid, hexamine and water (equations 1.1 to 1.3). During the blending operation (mixing of wood particles with adhesive), the presence of free water is residual since the moisture content of the blended particles is around 11 %, below the fibre saturation point of wood (around 30 % for most wood species) [46]. The absence of free water avoids the pre-cure reaction.…”

Section: Uf Resin Curementioning

confidence: 99%

“…Biomass on forest and other green vegetation remove carbon from atmosphere through the photosynthesis process, converting carbon dioxide and water into sugars for tree growth and release oxygen into the atmosphere [46] (equation 1.5):…”

Section: Green Carbon Cyclementioning

confidence: 99%

Adhesive systems for low formaldehyde emission wood-based panels

Costa

2014

International Wood Products Journal

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“…As the share of lowemitting glues increases in panel industry [8][9][10], the effect of wood particles and fibers on emissions will increase. Even small amounts of emission in indoor air will build up over time in modern energy-saving buildings with lower air exchange rates.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Dynamic Microchamber as a Quick Factory Formaldehyde Emission Control Method for Industrial Particleboards

Hemmilä

Zabka²,

Αδαμόπουλος

2018

Advances in Materials Science and Engineering

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e most common formaldehyde control method for wood panels in Europe, the perforator method, measures formaldehyde content, while most of the legal requirements in the world are based on emissions. Chamber methods typically used for emission measurements require too much time to reach steady state for factory quality control. e aim of this study was therefore to investigate whether emission values of particleboards measured one day after production would be usable for quality control purposes. e correlation between 1-day and 7-day emission values was determined using a dynamic microchamber (DMC).ree industrial board types that differed in density and emission levels were used for the evaluation. e online emission measuring equipment Aero-laser AL4021 connected to the 1 m 3 chamber was used to gain further information on the emission reduction behaviour of the different board types. Only the two particleboard types with higher densities showed good correlation between the 1-day and 7-day emissions. e overall results suggested that 1-day emission values can be used for factory quality control purposes; however, if the initial 1-day values are above the permitted level, extensive evaluation for each individual board type needs to be performed.

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Alternative to latent catalysts for curing UF resins used in the production of low formaldehyde emission wood-based panels

Cited by 66 publications

References 11 publications

Formaldehyde emission in wood based panels: effect of curing reactions

Formaldehyde emission in wood based panels: effect of curing reactions

Adhesive systems for low formaldehyde emission wood-based panels

Evaluation of Dynamic Microchamber as a Quick Factory Formaldehyde Emission Control Method for Industrial Particleboards

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