Formaldehyde emission and burning behaviors from wood- based ...

SHB2011 - 5th International Symposium on Sustainable Healthy Buildings, Seoul, Korea10 February 2011Formaldehyde emission and burning behaviors from woodbasedpanels according to various surface finishing methodsJeong-Hun Lee, Junhyun Kim and Sumin Kim *Building Environment & Materials Lab, School of Architecture, Soongsil University, Seoul156-743, Republic of Korea*Corresponding author: Sumin Kim(skim@ssu.ac.kr)AbstractIn this study, we investigated particleboard (PB) and medium density fiberboard (MDF), asexamples of wood-based panels that are used widely in the manufacture of furniture, flooring,housing and other industrial products. In order to use wood-based panels as a final product,they have to undergo surface finishing via various processes such as Low Pressure Laminate(LPL), Poly Vinyl Chloride (PVC), Coating Paper (CP), Direct Coating (DC) and VeneerOverlay & UV Coating (VO-UVC). We conducted tests to examine the reduction offormaldehyde emissions and burning behaviors according to these five surface finishingmethods. To determine formaldehyde emissions, we used the desiccator method according toJIS A 1901. The burning behaviors of wood-based panels were investigated using conecalorimeter at an incident heat flux of 50 kWm -2 according to ISO 5660-1. The formaldehydeemission of VO-UVC was lower than that of the other methods. In the burning tests, the heatrelease rate (HRR) of DC was higher than that of the other methods. The mass loss rate(MLR) when the product of DC was burned was higher than that of the other finishingmaterials.Keywords: Surface finishing method, burning behavior, cone calorimeter, formaldehyde,desiccator1. IntroductionRecently, people spend almost 90% of their time indoors, which presents a higher risk frominhalation of pollutants than outdoors. It has been reported that many people complain ofsymptoms of illness such as headaches, irritation of the nose, nausea, skin disorders, andfatigue after spending some time in new buildings or newly renovated housings in recentyears. Sick building syndrome (SBS) is a serious problem with the air quality caused byindoor contaminants in the home and work place [1-3]. SBS symptoms that are experienced327

SHB2011 - 5th International Symposium on Sustainable Healthy Buildings, Seoul, Korea10 February 2011Table 1. The characteristics of various surface finishing methods.Classification MethodReference panel UntreatedLow Pressure Saturating papers are cured on panel surface using hot press processLaminates LPL)Poly Vinyl PVC films are cured on panel surface at room temperature usingChloride (PVC) EVA(Ethylene Vinyl Acetate) resinCoating Paper The paper with resin coating cured on panel surface at room(CP)temperature using PVAC resinDirect Coating Polyester resin cured on panel surface using hot process or infrared(DC)Veneer Overlay Veneer overlay(0.2~0.6mm) glued on panel surface with PVAC or& UV Coating urea resin and cured using irradiation of UV(VO-UVC)2.2. Test method2.2.1. Formaldehyde emission by desiccator methodThe formaldehyde emissions from the MDF and PB were determined according to the JISmethod (JIS A 1460) using a glass desiccator. The 24-h desiccator method uses a common,10L glass desiccator with a volume. The emission test lasted 24 h in the covered desiccator ata temperature of 20°C. Samples of the non-edge sealed and edge sealed by three sealingmethods all underwent testing. The emitted quantity of formaldehyde was obtained from theconcentration of formaldehyde absorbed in a Petri dish filled with a specified amount ofdistilled or deionized water. The absorbed formaldehyde was analyzed by using thechromotropic acid method. The principle for determining the concentration of formaldehydeabsorbed in the distilled or deionized water is based on the Hantzsch reaction in which theformaldehyde reacts with ammonium ions and acetylacetone to yield diacetyldihydrolutidine.For each of the emission tests, the three different grades of the MDF and PB specimens weretested: E0, E1 and E2. As a reference test, MDF and PB specimens without surface finishingtreatment were tested in addition to the other specimens with the five surface finishingtreatments, giving a total of 36 experimental specimens.2.2.2 Cone calorimeterThe cone calorimeter is recognized worldwide as one of the most acceptable fire testingapparatuses. Fig. 1 presents a schematic view of the cone calorimeter. To confirm the burningbehavior of the panels, specimens of dimensions 100mm x 100mm x 18 mm thickness werefabricated. The experimental results were calculated based on the average of threeexperimental data for each test.All the experiments were conducted by placing the specimens in the same holder in ahorizontal position under the cone heater with 50kWm-2 of heat flux. In the cone calorimeter329

SHB2011 - 5th International Symposium on Sustainable Healthy Buildings, Seoul, Korea10 February 2011test, the heat release rate (HRR), total heat rate and mass loss rate (MLR) were investigated.The cone calorimeter test was conducted according to ISO-5660-1 standard.Fig. 1. Schematic diagram of the cone calorimeter.3. Results and discussion3.1 Formaldehyde emissionTo confirm the formaldehyde emission in accordance with the six surface finishing methods,the panels were tested by the simple and inexpensive desiccator method, as defined in KS F3104 and KS F 3200, which are similar to JIS A 1460 (Building boards determination offormaldehyde emission-desiccator method).For the MDF panels, the emissions of the E0 grade (1.5mg/L), there was clear variation among the six specimens. The DC and VO-UVC emissions were lower than the reference value, by approximately 20% for the latter. Fig.2 shows the formaldehyde emissions of the MDF specimens.330

SHB2011 - 5th International Symposium on Sustainable Healthy Buildings, Seoul, Korea10 February 2011To summarize these emission test results, the DC and VO-UVC methods showed the lowestemission levels regardless of the natural emission grade of product. Unlike other methodsinvolving room temperature curing, the DC method includes hot or infrared curing and theVO-UVC method includes UV irradiation curing. This explains that the free formaldehydedecomposition and reduction in the curing process. However, the LPL method, whichincludes a hot pressing process for curing, showed different behaviors.3.2 Burning behaviorsTo determine the variations of burning behavior among the six surface finishing methods, theburning behaviors were investigated using a cone calorimeter. Only E2 grade specimens wereused in the cone calorimeter test. The cone calorimeter is a performance-based, bench scale,fire-testing apparatus that provides comprehensive insight into not only fire risks such as (Edthisacronym has already been defined above) HRR, total heat release (THR), and time toignition, but also fire hazards such as smoke release and CO production. However, in thisstudy the cone calorimeter was conducted to test and confirm the fire risks according to thesurface finishing methods.The FR and burning behaviors were evaluated with a heat flux of 50kWm -2 over a totalduration from complete installation of the specimen until the flame was turned off. The HRRand MLR of PB and MDF according to each surface finishing method are shown in Figs. 4and 5.300MDF300PB250200ReferencepanelLPL250200ReferencepanelLPLHRR (kW/m 2 )15010050PVCCoating PaperDirect CoatingHRR (kW/m 2 )15010050PVCCoating PaperDirect Coating00 250 500 750 1000 1250 1500-50Time(s)Veneer Overlay+ UV Coating00 250 500 750 1000 1250 1500-50Time(s)Fig. 4. HRR of MDF and PB for the six surface finishing methodsVeneer Overlay+ UV CoatingFig. 5. MLR of MDF and PB for the six surface finishing methods332

SHB2011 - 5th International Symposium on Sustainable Healthy Buildings, Seoul, Korea10 February 2011The DC method showed higher HRR for both MDF and PB than the other specimens.However, the MDF and PB specimens showed similar patterns regardless of the surfacefinishing method with only negligible differences. MLR showed a similar trend to that ofHRR. (Ed- this sentence is unnecessary as you’ve already stated the same in the previoussentence)The THR results are shown in Fig.6. The DC method showed the highest values for bothMDF and PB. Generally, in the cone calorimeter test, the HRR and THR of MDF were higherthan those of PB.Fig. 6. THR of MDF and PB for the six surface finishing methods4. ConclusionThe formaldehyde emissions and burning behaviors of PB and MDF, which are commonlyused as furnishing materials, were evaluated as a function of six different surface finishingmethods.The formaldehyde emissions for the E2 grade specimens varied significantly among the sixsurface finishing methods. The DC and VO-UVC methods were the most effective overall inreducing formaldehyde emissions. Thus, pollutants emitted by wood-based boards can bereduced by changing the surface finish method. However, the formaldehyde emissions of theLPL specimens far from reduction despite the absence of any adhesives and the inclusion of ahot press curing process. This is greatly different from the basic concept which formaldehydeemission shielding from the surface of wood-based products would significantly decrease theoverall emissions.The combustion and fire resistance varied slightly according to the surface finishing type.The initial HRR was slightly higher for DC than for the other surface finishing types.However, the difference was negligible. In comparison with a previous study and otherinterior materials the panel specimens retained higher initial HRR and THR, indicating thatthe fire resistance or FR retardant performance cannot be guaranteed for only surfacetreatment. Thus, to grant FR performance the other methods should be designed andconducted the test to confirm the burning behaviors.333

SHB2011 - 5th International Symposium on Sustainable Healthy Buildings, Seoul, Korea10 February 2011AcknowledgementsThis research was supported by Basic Science Research Program through the NationalResearch Foundation of Korea (NRF) funded by the Ministry of Education, Science andTechnology (No. 2010-0001860).References[1] Hodgson, M. (2002) Indoor environmental exposures and symptoms. Environ. HealthPerspect. 110(4), 663-667.[2] Menzies, D., Bourbeau, J. (1997) Building related illnesses. New Eng. J. Med. 337, 1524-1531.[3] Lee, S.-W., Yang, Y.-S., Ahn, T.-H., Bae, C.-S., Moon, C.-J., Kim, S.-H., Song, S.-Y.,Hwang, H.-Z., Kim, J.-C. (2007) Subacute toxicity evaluation in rats exposed to concreteand hwangto building environments. Environ. Toxicol. 22(3), 264-274.[4] Franck C. Eye symptoms and signs in buildings with indoor climate problems ('OfficeEye Syndrome'). Acta Ophthalmologica 1986;64:306-11.[5] Kjærgaard SK, Pedersen OF, Taudorf E, Mølhave L. Assessment of changes in eyeredness by a photographic method and the relation to sensory eye irritation. InternationalArchives of Occupational and Environmental Health 1990;62:133-7.[6] Andersson K, Bakke JV, Bjorseth O, Bornehag CG, Clausen G, Hongslo JK, et al. TVOCand health in non-industrial indoor environments. Indoor Air 1997;7:78-91.[7] Choi DW, Moon KW, Byeon SH, Lee EI, Sul DG, Lee JH, et al. Indoor volatile organiccompounds in atopy patients' houses in South Korea. Indoor and Built Environment2009;18:144-54.[8] James JP, Yang X. Emissions of volatile organic compounds from several green and nongreenbuilding materials: a comparison. Indoor and Built Environment 2005;14:69-74.[9] Zhang Y, Xu Y. Characteristics and correlations of VOC emissions from buildingmaterials. International Journal of Heat and Mass Transfer 2003;46 (25):4877-83.[10] P.K. Kawouras, D. Koniditsiotis and J. Petinarakis, Resistance of cured ureaformaldehyderesins to hydrolysis, Holzforschung 52 (1998), pp. 105–110.[11] R. Vansteenkiste, Surface treatment of wood based panels, Seminar on Wood BasedPanels and Furniture Industries, Beijing, China, 1981.[12] S. Kim and H.-J. Kim, Anti-bacterial performance of colloidal silver-treated laminatewood flooring, Int. Biodeterior. Biodegrad. 57 (2005), pp. 155–162.[13] G. Nemli and G. Çolakog lu, The influence of lamination technique on the properties ofparticleboard, Build. Environ. 40 (2005), pp. 83–87.[14] A. Grigoriou, Formaldehyde emission from the edges and faces of various wood basedmaterials, Holz Roh Werkst. 45 (1987), pp. 63–67.[15] Ondrej Grexa, Franck Poutch, Desana Manikova, Helena Martvonova and AndreaBartekova, Intumescence in fire retardancy of lignocellulosic panels, Polymer Degradationand Stability Volume 82, Issue 2, 2003, Pages 373-377334