Forest products plywood

Approximately one million metric tons of urea-formaldehyde resin are produced annually all over the world. More than 70% of this urea-formaldehyde resin is consumed by the forest products industry. The resin is used in the production of an adhesive for bonding particleboard (61% of the urea-formaldehyde used in the industry), medium-density fiberboard (27%), hardwood plywood (5%), and as a laminating adhesive (7%) for bonding furniture case goods, overlays to panels, and interior flush doors, for example. 

Below-grade walls may be constructed of poured concrete, masonry blocks, or other materials such as all-weather wood or stone. This chapter discusses details for use of poured concrete and masonry foundation because these are the materials most commonly used for new construction. Recently, trade associations such as American Plywood Association (APA) and the National Forest Products Association (NFoPA) have issued publications on designing radon resistance permanent wood foundations. Information on these types of foundations can be found by contacting the appropriate trade association.21... 

The success obtained in this study on bonding flake board and maple blocks supports the possibility of using OSL in resins for bonding crosswise laminates (i.e., plywood). Subsequent research conducted at the Mississippi Forest Products Utilization Laboratory on OSL-PF resins for bonding plywood has been equally successful. 

One of the ubiquitous by-products of the forest products industry at plant site is bark residues. While some bark is used as fuel and in agriculture, in particular soil applications, considerable amounts of bark remain unused (6 7). A recent survey in Oregon indicated that the lumber and plywood industries generated annually a total of 3.0 million dry tons of bark. 

Returning to the gluing operation and expanding the discussion on the chemical aspects of plywood gluing is desirable. James A. Klein gave an excellent presentation (at the 1975 Forest Products Research Society Annual... 

Perhaps the most extensive area of research in simple pretreatment systems to enhance the weathering properties of wood has involved application of inorganic salt solutions. Much of the early work in this field was undertaken at the U.S. Forest Products Laboratory in Madison, Wisconsin and was aimed at improving the performance of transparent finishes. Black [25] described an experimental chromate-based wood finish and Black and Mraz [26] discovered that both acid and ammoniacal-copper chromate treatments significantly improved the performance of clear finishes on western red cedar, redwood (Sequoia sempervirens), and Douglas fir plywood. Later research [27] demon-... 

Since the construction industry is one of the big consumers of the plywood as concrete forms which are originally coming from the tropical rainforests, environmental problems concerning tropical rainforests are very important and urgent for the industry. Considering the substituting materials for the plywood as concrete forms, what came up is the recycled paper resources which are also forest products. 

Dai C, Throughton G and Wang B (2003). Development of a new incising technology for plywood/LVL production. Part I. Incising at the lathe and its effect on veneer quality and recovery. Forest Products Journal, 55(3) 73-9... 

Spelter H and Sleet G (1989) Potential reductions in plywood manufacturing costs resulting from improved technology. Forest Products Journal, 59(1) 8-15 Springate NC and Roubicek TT (1979) Improvements in lathe and clipper production. Modern Plywood Techniques, 7 51-61... 

Walser DC (1978) New developments in veneer peeling. Modern Plywood Techniques, 6 6-18 Wang X, Ross RJ, Mattson JA, Erickson JR, Forman JW, Geske EA and Wehr MA (2001) Several non-destructive evaluation techniques for assessing stiffness and MOE of small diameter logs. USDA, Forest Service, Forest Products Lahoratory, Research Paper RP-600 Wang X, Ross RJ, Bradshaw BK, Punches JRJ, Erickson JR, Forman JW and PeUerin RF (2004) Diameter effect on stress-wave evaluation on modulus of logs. Wood and Fiber Science, 55(3) 368-77... 

Wellons JD, Krahmer RL, Sandoe MD and Jokerst RW (1983) Thickness loss in hot-pressed plywood. Forest Products Journal, 55(1) 27-34 Welzbacher CR and Rapp AO (2002) Comparison of thermally modified wood originating from four industrial scale processes - durability. International Research Group on Wood Preservation. Document No. IRG/WP 02-20262 Wengert EM (1979) Lumber predrying a timely examination. Timber Process Industries, 4(9) 20-24... 

Woodfin RO (1973) Wood losses in plywood production - four species. Forest Products Journal, 25(9) 98-106... 

Product tests. Clearly, the best product test is full-scale testing of finished panels under actual use conditions. This has been done (27,38) but is expensive, because several full-sized panels of each product must be pre-conditioned at constant temperature and humidity for at least a week. The next best approach is to test product samples in air chambers under standardized conditions. A summary of such methods is contained in Table I. A very large effort has been made over the last three decades world-wide to develop quick, reliable and meaningful product tests. Wittmann (16), Zartl (20), Plath (17), Verbestel (1, Neusser (21,22), Roffael (25), HUD, the U.S. Forest Products Industry (39,40), many standaraization organizations (41-43) and others have published many viable methods, but the testing involves a combination of complex factors and there is simply no single test that fulfills everybody s specific needs. Table I list some of the currently accepted test methods for formaldehyde emission from particleboard, plywood and medium density fiberboard. 

Myers, G. E., Formaldehyde dynamic air contamination by hardwood plywood effects of several variables and board treatments. Forest Products Journal, 1982 32(4) 20-25. 

Isocyanates are used in the forest products industry to adhesively bond wood chips, which are then pressed to form particleboard and oriented strandboard. Urethanes are also used to fill knotholes and surface defects in finished plywood boards ( plywood patch ). These filled systems must cure rapidly and be sanded easily. 

Most of the recent efforts to develop uses for the condensed tannins have centered on their application in wood adhesives. Reviews by Pizzi (182, 186) and others (15, 78, 87, 93, 208) provide references to several hundred papers and patents on this subject. Despite world-wide research efforts on other sources of tannins, particularly since the 1972-1973 petroleum shortage, the mimosa or wattle tannins extracted from the bark of black wattle Acacia mearnsii) remain the major source of condensed tannins exploited commercially for adhesive manufacture. Of the approximately 100000 tons of wattle tannin produced annually, only about 10000 tons are used in wood adhesives, predominantly in South Africa but also in Australia and New Zealand (186). The extensive use of wattle tannins by the wood products industry of South Africa is impressive indeed, as these tannins have partly replaced phenol and resorcinol usage in adhesives for bonding of particleboard, plywood, and laminated timbers (182, 186, 213). Three factors have contributed to the success in use of wattle tannin-based adhesives, namely the comparatively high costs of phenol and resorcinol in the Southern Hemisphere, their resorcinolic functionality and low molecular weight and, perhaps most importantly, the commitment by the research and industrial communities of these countries to reduce the reliance of the forest products industry on petroleum-based adhesives. 

New Zealand Forest Products Ltd. continued their research on the use of radi-ata pine tannins and had a 1 ton/day pilot plant operating by 1974 and a full-scale plant in operation from mid-1981 to 1987. These tannin extracts were marketed under the trade name Tannaphen (Woo, 1982, personal communication). The extracts were used in bonding of both plywood (described below) and particle board. The Tannaphen extract (100 parts) is combined with a defoamer (0.5 parts), paraformaldehyde (6-10 parts), and parafin wax (10 parts) it is sprayed on wood chips at a loading of 10% to 12% by weight of solids on the face and 7% to 9% by weight of solids on the core particles. Panels 20 mm thick are pressed for 7 minutes at 170°C to obtain panels with the properties shown in Table 10.3.4. These panels were marketed primarily as a flooring material in New Zealand. While not classified as exterior panels, these Tannaphen-bonded boards re-... 

Woo (1982, personal communication) has described the exterior plywood adhesive formulation based on Tannaphen and used commercially by New Zealand Forest Products Ltd. since 1981 as Tannaphen - 56 parts, a phenol-formaldehyde fortifying resin - 21 parts, olivestone flour - 18 parts, and paraformaldehyde - 5 parts on weight of solids. These adhesives are tolerant of open assembly times of 20 minutes, closed assembly times of up to 4 hours, and veneer moisture contents of up to 15%. Both shear strengths and wood failure were comparatively high even after 5 weeks in water at 25 °C. 

Columbia Forest Products applied the principle that imparts adhesive ability to the blue mussel, to design a soy-based formaldehyde-free technology in the construction of hardwood and plywood products. The WhalePower Company designed wind turbine blades using the Tubercle Technology to help them be quieter, more reliable when winds fail, and perform better in turbulent winds (WhalePower 2013). The technology is based on the idea that humpback whales are agile in spite of their size because of bumps on their fins. 

The resorcinol-pattern proanthocyanidins are widely used not only for leather tanning, but also for a range of other commercial products, particularly as adhesives for plywood and fiberboard (6,7). Wattle tannin is produced from sustained-yield forests of Acacia mearnsii. largely in southern Africa (6,8). Some of the impetus at least to develop other uses for wattle tannin, apart from... 

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