By MUHAMMAD AIZAT BIN ABD GHANI, Research Officer INTROP
Wood based panels (WBP) are widely used in furniture manufacturing and also as an interior decoration. These products are broadly used in building for decoration, construction and furnishing of homes, office, schools and another places (Kim et al, 2010). Urea formaldehyde (UF) are commonly resin used as the adhesive/binder in WBP manufacturing. Nevertheless, this WPBs bonded with formaldehyde-based resin are likely can emitting formaldehyde during their service life which know as formaldehyde emission (FE), and this FE can cause an indoor pollution to human health.
A World Health Organization (WHO) and US Environmental Agency (EPA) has classified formaldehyde as potentially dangerous, plausible as a human carcinogen under the condition of unusually high or prolonged exposure. The effects are, occupants would experience various symptoms such as headache, nose and throat irritation and fatigue (Kanazawa et al., 2010)
According to Zhang et al., (2018) FE generally came from three sources. First, the formaldehyde compound contained in wood material where it comes from thermolysis of wood lignin and polysaccharides in the wood fiber can contribute toward FE from the manufactured WBP. Second is from free residual formaldehyde that were not react in the adhesive’s reaction. This unreacted-formaldehyde will in time migrate and be released into atmosphere, especially under high temperature and when exposed in a well-ventilated environment. Third is the emission from the formaldehyde degradation structure through hydrolysis of the WBP used.
At lower concentration, human is able to detect the present of formaldehyde where the limit of awareness lies depending on the personal sensitivity which between 0.05 mg/L to 1 mg/L. It is important to control the FE in order to protect the population against risk and harm by exposure from this colorless gas. For this reason, many countries such as Japan, Europe and United Sates had set regulation and standard for the releases of formaldehyde from WBP. In Japan, the FE level is defined by the Japanese Industrial Standard (JIS, 2001)) with 3 classes of formaldehyde classification which are F** (£ 1.5 mg/L to 2.1 mg/L), F*** (£ 0.5 mg/L to 0.7 mg/L) and F**** where the emission limit is £ 0.3 mg/L up to 0.4 mg/L. The emission limit of F** class is approximately equivalent to European E1 class, F*** and F**** emission limits are much lower than E1 class. In 2009, the California Air resources Board (CARB) established ASTM E1333 standard known as CARB phase 1 and on 2010, it has been revised to CARB 11 with lower limit from the previous standard, as for particleboard the limit is 0.18 ppm to 0.09 ppm, while 0.21 ppm to 0.11 ppm for medium density fiberboard (MDF) FE limit. Different type of WBP is usually tested by different methods and different countries have their own limit and regulations.
Responding to consumer concerns and regulatory actions, involves WBP industries have made a major improvement in reducing FE from their products especially bonded with UF resin. This progress was achieved by employing one or more technological advances. Different strategies to reduce FE have been attempted as for example, is to improve the UF rein synthesis and curing process, changing and decreasing the formaldehyde/urea molar ratio (Dongbin et al., 2006). Other than to incorporate chemical additives called formaldehyde scavenger directly to the resin (Boran et al., 2011) and addition of modifiers in the UF synthesis (Amazio et al., 2011) also application of post-treatment on the surface of the WBP (Nemli and Colakoglu, 2005).
Generally, awareness on FE should be improved among public especially furniture consumer since they are not really equipped themself on the risks and hazardous of this compound. User also should be well-informed the consequence if they are exposed too much in the long period to formaldehyde specifically from furniture in their house. As for government, a set of regulation and decisive action should be imposed and taken on the WBP manufacturer in order to regulate and control the maximum level emission from the WBP that can be harmful over the time to the user. All researcher is also highly encouraged to produce and develop green adhesive or free formaldehyde-resin to be used as an alternative’s binder in WBP manufacturing in the future.
Kim, K. W., Kim, S., Kim, H. J., & Park, J. C. (2010). Formaldehyde and TVOC emission behaviors according to finishing treatment with surface materials using 20 L chamber and FLEC. Journal of hazardous materials, 177(1-3), 90-94.
Kanazawa, A., Saito, I., Araki, A., Takeda, M., Ma, M., Saijo, Y., & Kishi, R. (2010). Association between indoor exposure to semi‐volatile organic compounds and building‐related symptoms among the occupants of residential dwellings. Indoor air, 20(1), 72-84.
Zhang, J., Song, F., Tao, J., Zhang, Z., & Shi, S. Q. (2018). Research Progress on Formaldehyde Emission of Wood-Based Panel. International Journal of Polymer Science, 2018.
Dongbin, F., Jianzhang, L., & An, M. (2006). Curing characteristics of low molar ratio urea-formaldehyde resins. Journal of Adhesion and Interface, 7(4), 45-52.
Boran, S., Usta, M., & Gümüşkaya, E. (2011). Decreasing formaldehyde emission from medium density fiberboard panels produced by adding different amine compounds to urea formaldehyde resin. International Journal of Adhesion and Adhesives, 31(7), 674-678.
Amazio, P., Avella, M., Emanuela Errico, M., Gentile, G., Balducci, F., Gnaccarini, A., ... & Belanche, M. (2011). Low formaldehyde emission particleboard panels realized through a new acrylic binder. Journal of Applied Polymer Science, 122(4), 2779-2788.
Nemli, G., & Çolakogˇlu, G. (2005). The influence of lamination technique on the properties of particleboard. Building and Environment, 40(1), 83-87.
Date of Input: 10/12/2020 | Updated: 10/12/2020 | norfaryanti
Universiti Putra Malaysia
43400 UPM Serdang
Selangor Darul Ehsan