Fiberboard and Hardboard Research at the Forest Products Laboratory: a 50-Year Summary
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United States Department of Agriculture Fiberboard and Forest Service Hardboard Forest Products Laboratory Research at the General Technical Report Forest Products FPL-47 Laboratory A 50-Year Summary Abstract On the Cover Many changes have occurred in the Top. Racking test of full-scale (9-by fiber-based panel products industries 14-ft) wall section with fiberboard during the past 50 years. During this sheathing conducted at FPL in timespan the Forest Products 1932. Laboratory has conducted a Bottom. Small-scale (2-by 2-ft) wall considerable amount of research on racking test developed at FPL in processing and product evaluation of 1976 as an economical way to fiber-based panel product materials. augment full-scale testing. Unfortunately about 26 percent of this information was never published. This report compiles all of the studies completed during this timespan and briefly summarizes what was accomplished. Keywords: Hardboard, fiberboard, summary, processing, raw materials, properties, performance. October 1985 Myers, Gary C.; McNatt, J. Dobbin Fiberboard and hardboard research at the Forest Products Laboratory: A 50-year summary. Gen. Tech. Rep. FPL-47. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory; 1985. 39 p. A limited number of free copies of this publication are available to the public from the Forest Products Laboratory, One Gifford Pinchot Drive, Madison, WI 53705. Laboratory publications are sent to over 1,000 libraries in the United States and elsewhere. The Laboratory is maintained in cooperation with the University of Wisconsin. Contents Page Introduction . 1 Manufacturing and Raw Material Variables . 2 Fiber Resources, 2; Fiber Preparation, 2 Additives and Fiber Treatments . 8 Sizing Materials, 8; Resins, 8; Other Additives, 11 Forming Procedures . 12 Hot-pressing . 13 Post-treatment . 15 Correlation Between Manufacturing Variables and Hardboard Performance . 15 Physical Properties . 16 Equilibrium Moisture Content (EMC), 16; Linear Expansion, 16; Water Adsorption and Thickness Swelling, 16; Thermal Conductivity, 17; Dielectric Properties, 17; Fire Performance, 18; Acoustical Absorption and Sound Transmission, 19 Mechanical Fastener Performance . 19 Screwholding, 19; Lateral Nail Resistance, 19; Wall Racking Strength, 19; Lateral Staple Resistance, 23 Hardboard Glue-Bond Strength . 24 Hardboard Machining Properties . 24 Basic Strength and Elastic Properties . 24 Effects of Loading Conditions and Specimen Dimensions on Mechanical Properties . 26 Effect of Moisture on Physical and Mechanical Properties . 28 Hardboard and Fiberboard Durability . 30 Hardboard and Fiberboard Performance in Use . 30 Structural Sandwich Panels, 30; Stressed-Skin Panels, 30; Roof Support Systems, 30; Hardboard in Shipping Pallets, 30 Summary . 32 References . 33 Availability of Studies Cited . 38 Sources of Free Information, 38; Sources which Charge a Fee, 38; Addresses of Sources, 38; Availability of Specific Journals, 39; Items Available from Forest Products Laboratory, 39; Other Sources of Information, 39 Fiberboard and Hardboard Research at the Forest Products Laboratory A 50-Year Summary Gary C. Myers, Research Forest Products Technologist J. Dobbin McNatt, Research Forest Products Technologist Forest Products Laboratory, Madison, WI Introduction The Forest Products Laboratory, U.S. Different terms have been used to A more recent development is Department of Agriculture, Forest identify the various panel products medium-density fiberboard (MDF), Service, has been conducting research made from wood fibers and intended which combines the technologies of the on fiber-based panel products since the primarily for building construction and hardboard and particleboard industries. early 1930’s (Luxford 1932), and was furniture and cabinet manufacture. The There was much debate over the probably the only public institution Wood Handbook (Forest Products definition of MDF until the American actively engaged in systematic wood Laboratory 1974) refers to them as Hardboard Association and the National research during the 1930’s and early “building fiberboards.” The American Particleboard Association jointly 1940’s. This report is a compilation of Society for Testing and Materials sponsored an American National all the studies completed at the definitions (ASTM 1978a) refer to them Standards Institute standard for MDF Laboratory and a summary of what was as “fibrous-felted boards,” divided (ANSI 1980). Medium-density accomplished. About 26 percent of the further into “structural insulating boards” fiberboard is manufactured from wood references and findings were never (less than 31 pounds per cubic foot fibers combined with a synthetic resin, published, but are on file at the (Ib/ft3)) and “hardboards” (greater than usually urea formaldehyde, and is Laboratory. These findings were not 31 Ib/ft3). In this paper “cellulosic intended for interior use. It has been made public because the scientist did fiberboard” means wood-fiber panels of replacing other panel products in the not think existent information justified 10 to 31 lb/ft 3 . furniture industry, and has experienced publication or because the information Cellulosic fiberboard, the oldest of the phenomenal growth in the United was presented in a letter or report to fiber-base panels, was developed in States and worldwide. another agency or to industry as part of 191 4. The production of cellulosic a cooperative venture. fiberboard has peaked and is now In addition to the experimental declining. A process for manufacturing research reported here, FPL has also a hard-pressed fiberboard (hardboard) produced information (FPL resource was developed in 1926. Hardboard bulletins) on hardboard and fiberboard production has been increasing, with raw material requirements, production, some of the biggest gains occurring in and uses (Dickerhoof 1978a, 1978b; hardboard siding. High-density Dickerhoof and McKeever 1979; hardboard is also starting to find uses McKeever 1979). as a structural material (McNatt 1980). Manufacturing and Raw Material Variables Fiber Resources Regardless of the source, many chips laboratory-size Asplund Defibrator become moldy or begin to decay during (Razzaque 1962; Schwartz 1958a; Fiber can be obtained from a multitude storage in large piles. The effect of this Schwartz and Baird 1952; Steinmetz of sources besides the traditional deterioration on hardboards made from 1968). Two studies (Schwartz 1963b, pulpwood. One good source is waste chips was investigated by Myers Schwartz and Baird 1950a) measured from other primary forest products (1983), Razzaque (1962), Schwartz and the amount of power consumed during processes, including sawmill wastes Chaline (1950b). Generally, they found the refining of hardboard furnish in (Schwartz and others 1947a, 1947b, a strength reduction and/or an increase laboratory-size attrition mills. Schwartz 1950a; Turner and Kern 1956; Forest in linear movement. (1958b) and Steinmetz (1973) Products Laboratory 1950), logging investigated effects of the type and wastes (Schwartz and others 1947b), Fiber Preparation severity of the fiber preparation chipper rejects and various pulpmill procedures on yield of fiber (table 4). wastes (Forest Products Laboratory Before it is possible to make any type Schwartz (1958b) showed also how the 1950), and veneer scrap (Schwartz of fiberboard, it is necessary to break fiber yield influences wet-forming 1951c). Schwartz and Baird (1952) down the raw material into individual characteristics and board performance made an early attempt to use fibers or fiber bundles. These are (table 5). Steinmetz (1973) made some branchwood only as a fiber source, and generally lignocellulose fibers obtained attempt to remove extractives with hot more recently Steinmetz and Fahey from some form of wood chip. Several water and dilute caustic washes to (1979) described the use for this means of reducing wood chips to fibers improve the suitability of some wood purpose of whole tree material, which is have been examined in the past, when species for hardboard manufacture the entire aboveground portion of the limitations of laboratory equipment (fig. 1). tree. Laundrie and McNatt (1975) largely controlled the type of study Several fiber characteristics can investigated urban forest as a source of conducted. The Laboratory possessed ultimately affect board performance. diseased trees for use in hardboard. an assortment of chemical pulp Several studies (Nelson 1973, Schwartz They also considered industrial discards digesters, various sizes and types of and Baird 1950a, Steinmetz and Fahey of used pallets, and wood from old atmospheric pulp refiners, and a small 1971, Turner and Kern 1956) have railroad cars, while Steinmetz (1974) laboratory-size Asplund Defibrator. shown how the different screen considered waxed corrugated as a Nearly all of the studies on fiber fractions can affect drainage rate on the source of fiber. Both Laundrie and preparation that were completed were machine as well as appearance and McNatt (1 975) and Schwartz (1951a) part of other, perhaps larger, studies. performance of the board. Hrubesky investigated municipal solid wastes Few, if any, had fiber preparation as a (1949) and Hrubesky and Perot (1954) which contain large quantities of primary objective. showed drainage rate is sensitive to wastepapers. Laundrie and McNatt In a few studies (Razzaque 1962; other variables also. Nelson (1 973) (1975) also investigated the much Schwartz et al. 1947b, 1950b) mild showed