In April 2008, the State of California adopted an airborne toxic control measure (ATCM) to reduce formaldehyde emissions from composite wood products, proposed by the California Air Resources Board (CARB), part of the California Environmental Protection Agency. Phase 1 started in January 2009, and at the end of the implementation, in July 2012, formaldehyde emission limits will range between 0.05 and 0.13 ppm, depending on the type of products, based on the ASTM E 1333 Large Chamber Method.
These new limits are in the order of the limits of detection of the current analytical methods presently used, and rendered the chromotropic acid reaction, on which the ASTM E 1333 is based, with a limit of detection of 0.01 ppm less precise.
The use of Near Infrared technology was investigated in 2009/2010. This analytical technique was not initially considered to be sensitive enough to measure formaldehyde emissions at very low levels. Recent developments in the broadband sources of near infrared radiation available and the type of detectors used have contributed in recent years to improve spectral stability and sensitivity. Some instruments have recently been tested in Europe and equipment suppliers claim that these systems can be used for online monitoring of formaldehyde emissions. This analytical technique is not recognized at this time by Canadian and US regulatory authorities and more testing was required to demonstrate the system’s reliability. Commercial products with very low free formaldehyde have been tested in 2009 with NIR sensors and results have been correlated with the ASTM E 1333 Large Chamber test results. At least one Canadian panel manufacturer has already expressed interest in running a mill trial. Results will be presented to regulatory authorities.
To improve the flame resistance of oriented strand board (OSB) and low-density fiberboard (ceiling tile), a laboratorial study was carried out to coat the commercial OSB panel and ceiling tile with three commercial fire retardant coatings (WT-102, Safe-T-Guard®, RUFR-1000) and ceiling tile with nanoclay 1130E-modified commercial coating/paint. The commercial coating and paint without fire retardants were designed for ceiling tile application. The test results indicated that the 2 wt% nanoclay-modified coating and/or paint could effectively improve the flame resistance of ceiling tile in terms of the short after-flame time according to ASTM D 3801 and the high limited oxygen index (LOI) according to ASTM D 2863. The nanoclay-modified coating and/or paint performed similarly to Safe-T-Guard® regarding both after-flame time and limited oxygen index. In general, the OSB panel coated with RUFR-1000 performed better than those with WT-102 and Safe-T-Guard® in terms of lowered panel consumption, net flame advance, insulation value and char index according to ASTM D 3806. An increase in fire retardant coating rate improved the fire performance of OSB for all three commercial fire retardant coatings.
Full title: Development of fire retardant composite panels. Part IV. Improvement of fire performance of OSB and ceiling tile via surface coating with commercial fire retardant coatings for OSB and ceiling tile and nanoclay-modified coating/paint for ceiling tile
An experiment was conducted to evaluate the fire performance of randomly oriented strand boards manufactured with two fire retardants (FR: CROS 349 and BUDIT 380), two nano-particles (NP: Nanofil®9 and Cloisite 25A), woven glass fiber (WGF) and glass fiber (GF). These materials were only used in wood strands for panel surface layer. Liquid/powder phenol-formaldehyde (PF) combination system was used as binder. In case where the nano-particle was used, it was also incorporated into the surface powder PF resin. All resultant strand boards were evaluated for fire performance in terms of flame advance, panel consumption, insulation value and char index according to ASTM Standard D 3806-98, and mechanical and physical properties of boards such as internal bond (IB) strength, modulus of rupture (MOR) and modulus of elasticity (MOE), and 24-h thickness swelling (TS) and water absorption (WA) according to CSA Standard O437.1-93. This study showed that the use of FR, WGF and GF did not seem to have apparent impact on panel performance but NP did in terms of overall panel performance. With respect to all fire properties evaluated, no single treatment appeared to perform consistently better than others. However, laminating strand board with WGF was proven to be the most effective way to protect strand board against flaming in terms of reduced net flame advance and panel consumption. Treatment of strands with two fire retardants appeared to be also a promising method for improving board fire performance next to WGF. The two nano-particles used and the fire retardant BUDIT 380 performed better than other materials with respect to lowered insulation value of strand board. In addition, the two nano-particles and the fire retardant CROS 349 resulted in better fire performance strand board than did other materials in terms of lowered char index.
Development of fire retardant composite panels. Part VIII. Improvement of fire performance of OSB panel via post-treatment with fire retardants, nano-particles, nanocrystalline cellulose and woven glass fiber
To improve fire performance of oriented strand board (OSB), a laboratorial study was carried out to post-treat commercial OSB panel with phenol-formaldehyde (PF) resin containing various fire retardants (FR), nano-particles (NP) and nanocrystalline cellulose (NCC). The post-treatment also included the laminating of OSB panel with woven glass fiber (WGF) and with the same PF resin as a binder. The resultant OSB panels were tested for fire performance in terms of net flame advance, panel consumption, insulation value, and char index.
The test results indicated that the post-treatment improved the fire performance of OSB panel in terms of reduced net flame advance (up to 29%), panel consumption (up to 29%), insulation value (up to 17%), or char index (up to 33%), as compared to the untreated OSB panel. No treatment performed consistently better than others with regard to all fire properties measured, but laminating OSB panel with WGF appeared to be the most effective treatment for protecting OSB against flaming, which resulted in net flame advance decreased by 29%, panel consumption by 29%, and insulation value by 17%. An increase in the loading level of fire retardant from 10 to 15 parts or nano-particle from 5.3 to 13.1 parts per 100 parts of PF did not seem necessary for further improving fire performance for all additives.
Besides WGF, the post-treatments leading to apparently improved fire performance included: (1) fire retardant BUDIT 380 (10 parts/100 parts PF) and nano-particle Cloisite 25A (13.1 parts/100 parts PF) in terms of lowered net flame advance (25% and 24%, respectively); (2) nano-particle Nanofil®SE 3000 (5.3 parts/100 parts PF) in consideration of lowered panel consumption (18%); (3) fire retardant CROS 481A (15 parts/100 parts PF) with respect to lowered insulation value (16%); and (4) fire retardant CROS 349 (10 parts/100 parts PF) (33%), fire retardant CROS 334 (15 parts/100 parts PF) (33%) and nano-particle Nano Al2O3 (13.1 parts/100 parts PF) (31%) with regard to reduced char index. In addition, this study showed that coating OSB with PF alone also seemed to be effective approach for protecting OSB panel against flaming as well, indicated by the lowered net flame advance (20%), panel consumption (13%) and char index (28%).
A series of randomly oriented three-layer strand boards were manufactured in the lab with five commercial fire retardants (CROS 349, CROS 334, BUDIT 380, CROS 481A, ZB-467), six commercial nano-particles (Cloisite 30B, Cloisite Na+, Nano Al2O3, zinc oxide, zinc oxide anion, zinc oxide non) and a sodium form of nanocrystalline cellulose in the surface layer. The resultant strand boards were evaluated for fire performance in terms of flame advance, weight loss (right after fire test) and insulation value (after fire test and conditioning), and mechanical and physical properties of board such as internal bond (IB) strength, dry and wet modulus of rupture (MOR) and modulus of elasticity (MOE), and 24-h thickness swelling (TS) and water absorption (WA).
It was observed that when applied at 6% for liquid form (for CROS 349, CROS 334, BUDIT 380) or 3% for powder form (for CROS 481A, ZB-467) on a dry wood basis, all fire retardants had an influence on board mechanical/physical properties and fire performance as well (in terms of insulation values rather than net flame advance and weight loss right after fire test). CROS 334 and BUDIT 380 performed better than others in terms of improved insulation property. In consideration of both board mechanical/physical properties and fire performance, BUDIT 380 would be optimal for strand board, while CROS 349 and CROS 334 also showed the potential for further investigation.
The use of 2% nano-particles in both dispersion and powder forms on a dry wood basis had no big influence on board fire performance. Cloisite 30B and Cloisite Na+ slightly improved the board fire performance in terms of reduced flame advance, but had a negative impact on board mechanical properties. All nano-particles also improved board insulation property at 0-inch test position. It is expected that an increase in application level of nano-particles would help to improve board fire performance.
Application of 1% nanocrystalline cellulose (NCC) in sodium form on a dry wood basis via spraying improved board mechanical/physical properties and also slightly improved board insulation property (rather than flame advance and weight loss). It is expected that an increase of NCC content in wood treatment would allow further improving board performance with regard to mechanical/physical properties and/or fire performance in terms of insulation property.
A laboratorial study was carried out to evaluate the fire performance of two fire retardant base coatings (CB-533 and CB-534) and two fire retardant top coatings (CB-535 and CB-536). These base and top coatings were specially developed by Inortech Chimie Inc. for oriented strand board (OSB) and low-density ceiling tile applications. Six combinations of the base and top coatings were applied on OSB and ceiling tile specimens and all of the three-layer coated panels were tested for flame advance, panel consumption, insulation value and char index according to ASTM D 3806. The test results indicated that all coating combinations improved the fire performance of OSB and ceiling tile, as compared to the uncoated panels. The most effective coating against flaming was CB-534/CB-534 (three-layer base coating), followed by CB-534/CB-535 (two-layer base coating/one-layer top coating), among the six base/top coating combinations evaluated.
To improve the flame resistance of low-density fiberboard (ceiling tile), a laboratorial study was carried out to coat the commercial ceiling tile with three commercial fire retardant coatings (WT-102, Safe-T-Guard®, RUFR-1000). In general, the surface coating of low-density ceiling tile with the three fire retardant coatings effectively improved the fire performance of the board. The ceiling tile coated with RUFR-1000 performed better than those with WT-102 and Safe-T-Guard® in terms of reduced panel consumption, net flame advance, insulation value, and char index according to ASTM D 3806.
A laboratorial study was carried out to improve the fire performance of low-density fiberboard (ceiling tile) by incorporating various commercial fire retardants (FR), nano-particles (NP) and glass fiber (GF) into fibers during the mat forming process. Five FR (CROS 349, CROS 481A, CROS 334, Optibor, Polybor), two NP (Nano Al2O3 and Cloisite 25A) and one GF were examined. The ceiling tiles were evaluated for mechanical properties (transverse load at rupture and modulus of rupture) according to CAN/ULC-S706-09 and ASTM C 209-07, and fire performance (flame advance, panel consumption, insulation value and char index) according to ASTM D 3806-98.
An element analysis of aluminum (Al) in a ceiling tile made with Nano Al2O3 was performed to evaluate the chemical distribution in fibers. The test result indicated that Nano Al2O3 only penetrated into the top layer of the panel. Based on this result, it was expected that the chemical penetration was likely limited on the top layer when other NP and FR were used. Thus, the procedure employed in this work for incorporating an additive into fibers would not cause any leaking problem which in turn might contaminate the white water and possibly destroy the bacteria used in the cleaning of the water for recycling.
Addition of an additive in ceiling tiles showed some negative impact on the transverse load at rupture or modulus of rupture (MOR) of the panels, depending on each individual additive used. The use of FR at 10-15 wt% on dry fiber weight significantly improved the fire performance of ceiling tiles in terms of reduced net flame advance by 81%, 59% and 57% respectively, and lowered panel consumption by 56%, 29% and 40% respectively, as observed for CROS 481A, CROS 349 and CROS 334. FR Polybor also resulted in reduced net flame advance by 46%, but it caused more reduction in board strength than other additives: by 41% for transverse load and 17% for MOR. The insulation values of ceiling tiles were reduced by 20% for NP Cloisite 25A, 10% for Nano Al2O3 and 7% for FR Polybor when these additives were applied at 5 wt% based on the dry fiber weight. Adding GF (10% by weight) or NP Cloisite 25A (5% by weight) in ceiling tiles also lowered the char index by 35%.
This study also showed that no additive could perform consistently better than others in terms of both mechanical and fire properties of ceiling tiles. By taking board mechanical properties into account, it can be concluded that three FR (CRSO 349, CROS 481A, CROS 334) showed potential for protecting ceiling tiles against flaming regarding lowered net flame advance and panel consumption. One nano-particle (Cloisite 25A) also showed potential in terms of reduced insulation value and char index.